Philips P89LPC920, P89LPC921, P89LPC922 Technical data

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INTEGRATED CIRCUITS

USER MANUAL

P89LPC920/921/922

80C51 8-bit microcontroller with two-clock core

2 KB/4 KB/8 KB 3 V low-power Flash with 256 Byte RAM

2003 Nov 6

Philips Semiconductors

80C51 8-bit microcontroller with two-cycle instructions

2KB/4KB/8KB Flash with 256 Byte RAM

User Manual - Subject to Change

P89LPC920/921/922

2003 Nov 6 2

Philips Semiconductors

User Manual - Subject to Change

P89LPC920/921/922

Table of Contents

1. General Description................................................................................... 9

Pin configuration...................................................................................................... 9

20-Pin TSSOP, DIP Package .................................................................................. 9

Logic symbol............................................................................................................ 9

Pin Descriptions....................................................................................................... 11

Special Function Registers...................................................................................... 14

Memory organization ............................................................................................... 18

Data RAM arrangement................................................................................ 19

2. Clocks........................................................................................................ 21

Enhanced CPU........................................................................................................ 21

Clocks...................................................................................................................... 21

Clock definitions ...................................................................................................... 21

Oscillator clock (OSCCLK) ........................................................................... 21

Low speed oscillator option .......................................................................... 21

Medium speed oscillator option .................................................................... 21

High speed oscillator option.......................................................................... 21

Clock output............................................................................................................. 21

On-chip RC oscillator option.................................................................................... 22

Watchdog oscillator option ...................................................................................... 22

External clock input option....................................................................................... 23

Oscillator Clock (OSCCLK) wakeup delay .............................................................. 23

CPU Clock (CCLK) modification: DIVM register...................................................... 23

Low power select..................................................................................................... 24

3. Interrupts ................................................................................................... 25

Interrupt priority structure ........................................................................................ 25

External Interrupt pin glitch suppression ................................................................. 26

4. I/O Ports .................................................................................................... 29

Port configurations................................................................................................... 29

Quasi-bidirectional output configuration .................................................................. 29

Open drain output configuration .............................................................................. 30

Input-only configuration ........................................................................................... 31

Push-pull output configuration ................................................................................. 31

Port 0 analog functions............................................................................................ 31

Additional port features............................................................................................ 32

5. Power Monitoring Functions ...................................................................... 33

Brownout Detection ................................................................................................. 33

Power-on Detection ................................................................................................. 34

Power reduction modes........................................................................................... 34

6. Reset ......................................................................................................... 39

Reset vector ............................................................................................................ 40

7. Timers 0 and 1........................................................................................... 41

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User Manual - Subject to Change

P89LPC920/921/922

Mode 0..................................................................................................................... 42

Mode 1..................................................................................................................... 42

Mode 2..................................................................................................................... 43

Mode 3..................................................................................................................... 43

Mode 6..................................................................................................................... 43

Timer overflow toggle output ................................................................................... 46

8. Real-Time Clock/System Timer................................................................. 47

Real-time Clock source ........................................................................................... 47

Changing RTCS1-0 ................................................................................................. 47

Real-time Clock interrupt/wake up........................................................................... 48

Reset sources affecting the Real-time Clock........................................................... 48

9. UART......................................................................................................... 51

Mode 0..................................................................................................................... 51

Mode 1..................................................................................................................... 51

Mode 2..................................................................................................................... 51

Mode 3..................................................................................................................... 51

SFR space............................................................................................................... 51

Baud Rate Generator and selection ........................................................................ 52

Updating the BRGR1 and BRGR0 SFRs ................................................................ 52

Framing Error .......................................................................................................... 53

Break Detect............................................................................................................ 53

More about UART Mode 0....................................................................................... 55

More about UART Mode 1....................................................................................... 56

More about UART Modes 2 and 3........................................................................... 57

Framing Error and RI in Modes 2 and 3 with SM2 = 1 ............................................ 57

Break Detect............................................................................................................ 57

Double buffering ...................................................................................................... 58

Double buffering in different modes......................................................................... 58

Transmit interrupts with double buffering enabled (Modes 1, 2 and 3) ................... 58

The 9th bit (bit 8) in double buffering (Modes 1, 2 and 3)........................................ 59

Multiprocessor communications .............................................................................. 60

Automatic address recognition ................................................................................ 60

10. I2C interface ............................................................................................ 63

I2C Data register ..................................................................................................... 64

I2C Slave Address register...................................................................................... 64

I2C Control register ................................................................................................. 64

I2C Status register................................................................................................... 66

I2C SCL Duty Cycle registers I2SCLH and I2SCLL ................................................ 66

I2C operation mode................................................................................................. 67

Master Transmitter Mode.............................................................................. 67

Master Receiver Mode.................................................................................. 68

Slave Receiver Mode.................................................................................... 69

Slave Transmitter Mode................................................................................ 69

11. Analog comparators ................................................................................ 79

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P89LPC920/921/922

Comparator configuration ........................................................................................ 79

Internal reference voltage........................................................................................ 80

Comparator interrupt ............................................................................................... 80

Comparators and power reduction modes .............................................................. 80

Comparator configuration example ......................................................................... 81

12. Keypad Interrupt (KBI)............................................................................. 83

13. Watchdog Timer ...................................................................................... 85

Watchdog Function.................................................................................................. 85

Feed Sequence ....................................................................................................... 86

Watchdog Clock Source .......................................................................................... 88

Watchdog Timer in Timer Mode .............................................................................. 89

Power down operation............................................................................................. 90

Periodic wakeup from Power down without an external oscillator........................... 90

14. Additional Features.................................................................................. 91

Software reset ......................................................................................................... 91

Dual Data Pointers .................................................................................................. 91

15. Flash Memory.......................................................................................... 93

General description ................................................................................................. 93

Features .................................................................................................................. 93

Flash programming and erase................................................................................. 93

Using Flash as data storage: IAP-Lite..................................................................... 93

In-Circuit Programming (ICP) .................................................................................. 97

ISP and IAP capabilities of the P89LPC920/921/922.............................................. 97

Boot ROM................................................................................................................ 98

Power-On reset code execution .............................................................................. 98

Hardware activation of the Boot Loader .................................................................. 98

In-System Programming (ISP)................................................................................. 99

Using the In-System Programming.......................................................................... 99

In-Application Programming method ....................................................................... 104

IAP Authorization Key.............................................................................................. 104

User configuration bytes.......................................................................................... 109

User security bytes.................................................................................................. 110

Boot Vector.............................................................................................................. 111

Boot Status.............................................................................................................. 111

16. Instruction set .......................................................................................... 113

17. Revision History....................................................................................... 117

18. Index........................................................................................................ 119

2003 Nov 6 5

Philips Semiconductors

User Manual - Subject to Change

P89LPC920/921/922

2003 Nov 6 6

Philips Semiconductors

80C51 8-bit microcontroller with two-cycle instructions

2KB/4KB/8KB Flash with 256 Byte RAM

User Manual - Subject to Change

P89LPC920/921/922

List of Figures

P89LPC920/921/922 memory map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

On-chip data memory usage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Using the crystal oscillator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

On-chip RC oscillator TRIM register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Block diagram of oscillator control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Interrupt priority level. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Summary of interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Interrupt sources, interrupt enables, and power down wake-up sources . . . . . . . . . . . . . 27

.Number of I/O pins available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Port output configuration settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Quasi-bidirectional output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Open drain output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Input -only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Push-pull output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Port output configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Brownout options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Power reduction modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Power Control register (PCON). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Power Control register A (PCONA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Block diagram of Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Reset Sources register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Timer/Counter Mode Control register (TMOD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Timer/Counter Auxiliary Mode Control register (TAMOD). . . . . . . . . . . . . . . . . . . . . . . . . 42

Timer/Counter Control register (TCON) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Timer/Counter 0 or 1 in Mode 0 (13-bit counter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Timer/Counter 0 or 1 in Mode 1 (16-bit counter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Timer/Counter 0 or 1 in Mode 2 (8-bit auto-reload). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Timer/Counter 0 Mode 3 (two 8-bit counters) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Timer/Counter 0 or 1 in Mode 6 (PWM auto-reload) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Real-time Clock/System Timer block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Real-time Clock/System Timer clock sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

RTCCON Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

SFR Locations for UARTs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Baud rate generation for UART. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

BRGCON register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Baud rate generation for UART (Modes 1, 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Serial Port Control register (SCON) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Serial Port Status register (SSTAT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Serial Port Mode 0 (double buffering must be disabled) . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Serial Port Mode 1 (only single transmit buffering case is shown) . . . . . . . . . . . . . . . . . . 56

Serial Port Mode 2 or 3 (only single transmit buffering case is shown). . . . . . . . . . . . . . . 57

FE and RI when SM2 = 1 in Modes 2 and 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Transmission with and without double buffering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

2003 Nov 6 7

Philips Semiconductors

80C51 8-bit microcontroller with two-cycle instructions

2KB/4KB/8KB Flash with 256 Byte RAM

User Manual - Subject to Change

P89LPC920/921/922

I2C-bus configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

I2C Data register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

I2C Slave Address register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

I2C Control register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

I2C Status register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

I2C clock rates selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

I2C Control register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Format in the Master Transmitter Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Format of Master Receiver Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

A Master Receiver switches to Master Transmitter after sending Repeated Start . . . . . . 68

I2C Control register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Format of Slave Receiver Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Format of Slave Transmitter Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

I2C-bus serial interface block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Master Transmitter Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Master Receiver Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Slave Receiver Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Slave Transmitter Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Comparator control registers (CMP1 and CMP2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Comparator input and output connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Comparator configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Keypad Pattern register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Keypad Control register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Keypad Interrupt Mask register (KBM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Watchdog timer configuration.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Watchdog Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Watchdog Timer Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

P89LPC920/921/922 Watchdog Timeout Values.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Watchdog Timer in Watchdog Mode (WDTE = 1). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Watchdog Timer in Timer Mode (WDTE = 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

AUXR1 register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Flash Memory Control Registe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Assembly language routine to erase/program all or part of a page. . . . . . . . . . . . . . . . . . 96

C-language routine to erase/program all or part of a page . . . . . . . . . . . . . . . . . . . . . . . . 97

Boot Loader Address and Default Boot Vector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

Forcing ISP Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

In-System Programming (ISP) hex record formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

IAP error status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

IAP function calls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

Flash User Configuration Byte 1 (UCFG1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

User sector Security Bytes (SEC0, ..., SEC7). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Effects of Security Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Boot Vector (BOOTVEC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Boot Status (BOOTSTAT). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Instruction set summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

2003 Nov 6 8

Philips Semiconductors

User’s Manual - Preliminary -

General Description

P89LPC920/921/922

1. General Description

The P89LPC920/921/922 is a single-chip microcontroller designed for applications demanding high-integration, low cost solutions over a wide range of performance requirements. The P89LPC920/921/922 is based on a high performance processor architecture that executes instructions in two to four clocks, six times the rate of standard 80C51 devices. Many system level functions have been incorporated into the P89LPC920/921/922 in order to reduce component count, board space, and system cost.

Pin configuration

20-Pin TSSOP, DIP Package

P0.1/CIN2B/KBI1KBI0/CMP2/P0.0

P0.2/CIN2A/KBI2

P0.3/CIN1B/KBI3

P0.4/CIN1A/KBI4

P0.5/CMPREF/KBI5

VDD

P0.6/CMP1/KBI6

P0.7/T1/KBI7

P1.0/TXD

P1.1/RXD

P1.7

P1.6

/P1.5

RST

VSS

XTAL1/P3.1

CLKOUT/XTAL2/P3.0

INT1

/P1.4

SDA/INT0

/P1.3

SCL/T0/P1.2

Logic symbol

KBI0 KBI1 KBI2 KBI3 KBI4 KBI5 KBI6 KBI7

CLKOUT

CMP2 CIN2B CIN2A CIN1B CIN1A

CMPREF

CMP1

XTAL2

XTAL1

PORT0PORT3

VDDV

P89

LPC920

/921/

922

PORT1

TxD RxD T0 INT0 INT1 RST

SCL SDA

2003 Nov 6 9

Philips Semiconductors

User’s Manual - Preliminary -

General Description

Block diagram

2KB/ 4KB/ 8KB

Code Flash

Port 3

Configurable I/Os

Port 1

Configurable I/Os

P89LPC920/921/922

High Performance

LPC920/921/922 CPU

256 Byte

Data RAM

Internal Bus

UART

Real-Time Clock/

System Timer

Crystal or

Resonator

Port 0

Configurable I/Os

Keypad

Interrupt

Watchdog Timer

and Oscillator

Programmable

Oscillator Divider

Configurable

Oscillator

CPU

Clock

On-Chip

Oscillator

I2C

Timer0 Timer1

Analog

Comparators

Power Monitor

(Power-On Reset,

Brownout Reset)

2003 Nov 6 10

Philips Semiconductors

User’s Manual - Preliminary -

General Description

Pin Descriptions

Mnemonic Pin no. Type Name and function

P0.0 - P0.7 1, 20, 19,

18, 17, 16, 14,

1I/OP0.0 Port 0 bit 0.

20 I/O P0.1 Port 0 bit 1.

19 I/O P0.2 Port 0 bit 2.

18 I/O P0.3 Port 0 bit 3.

17 I/O P0.4 Port 0 bit 4.

16 I/O P0.5 Port 0 bit 5.

14 I/O P0.6 Port 0 bit 6.

13 I/O P0.7 Port 0 bit 7.

I/O Port 0: Port 0 is an 8-bit I/O port with a user-configurable output type. During reset

Port 0 latches are configured in the input only mode with the internal pullup disabled. The operation of port 0 pins as inputs and outputs depends upon the port configuration selected. Each port pin is configured independently. Refer to the section on I/O port configuration and the DC Electrical Characteristics for details.

The Keypad Interrupt feature operates with port 0 pins.

All pins have Schmitt triggered inputs.

Port 0 also provides various special functions as described below.

O CMP2 Comparator 2 output.

I KBI0 Keyboard Input 0.

I CIN2B Comparator 2 positive input B. I KBI1 Keyboard Input 1.

I CIN2A Comparator 2 positive input A. I KBI2 Keyboard Input 2.

I CIN1B Comparator 1 positive input B. I KBI3 Keyboard Input 3.

I CIN1A Comparator 1 positive input A. I KBI4 Keyboard Input 4.

I CMPREFComparator reference (negative) input. I KBI5 Keyboard Input 5.

O CMP1 Comparator 1 output.

I KBI6 Keyboard Input 6.

I/O T1 Timer/counter 1 external count input or overflow output.

I KBI7 Keyboard Input 7.

P89LPC920/921/922

2003 Nov 6 11

Philips Semiconductors

User’s Manual - Preliminary -

General Description

Mnemonic Pin no. Type Name and function

P1.0 - P1.7 12, 11,

10, 9, 8,

4, 3, 2

12 I/O P1.0 Port 1 bit 0.

11 I/O P1.1 Port 1 bit 1.

10 I/O P1.2 Port 1 bit 2. (Open-drain when used as outputs)

9I/OP1.3 Port 1 bit 3. (Open-drain when used as outputs)

8I/OP1.4 Port 1 bit 4.

4IP1.5 Port 1 bit 5. (Input only)

3I/OP1.6 Port 1 bit 6. 2I/OP1.7 Port 1 bit 7.

P3.0 - P3.1 7, 6 I/O Port 3: Port 3 is an 2-bit I/O port with a user-configurable output type. During reset

7I/OP3.0 Port 3 bit 0.

I/O

Port 1: Port 1 is an 8-bit I/O port with a user-configurable output type, except for

(for

three pins as noted below. During reset Port 1 latches are configured in the input

P1.0-

only mode with the internal pullup disabled. The operation of the configurable port 1

P1.4,

pins as inputs and outputs depends upon the port configuration selected. Each of

P1.6-

the configurable port pins are programmed independently. Refer to the section on

P1.7),

I/O port configuration and the DC Electrical Characteristics for details. P1.2 - P1.3

I (for

are open drain when used as outputs. P1.5 is input only.

P1.5)

All pins have Schmitt triggered inputs.

Port 1 also provides various special functions as described below.

O TxD Transmitter output for the serial port.

I RxD Receiver input for the serial port.

I/O T0 Timer/counter 0 external count input or overflow output. (Open-drain

when used as outputs)

I/O SCL I

I INT0

I/O SDA I2C serial data input/output.

I INT1

I RST

Port 3 latches are configured in the input only mode with the internal pullup disabled. The operation of port 3 pins as inputs and outputs depends upon the port configuration selected. Each port pin is configured independently. Refer to the section on I/O port configuration and the DC Electrical Characteristics for details.

All pins have Schmitt triggered inputs.

Port 3 also provides various special functions as described below:

O XTAL2 Output from the oscillator amplifier (when a crystal oscillator option is

O CLKOUTCPU clock divided by 2 when enabled via SFR bit (ENCLK - TRIM.6).

C serial clock input/output.

External interrupt 0 input.

External interrupt 1 input.

External Reset input (if selected via FLASH configuration). A low on this pin resets the microcontroller, causing I/O ports and peripherals to take on their default states, and the processor begins execution at address 0.

selected via the FLASH configuration).

It can be used if the CPU clock is the internal RC oscillator, watchdog oscillator or external clock input, except when XTAL1/XTAL2 are used to generate clock source for the real time clock/system timer.

P89LPC920/921/922

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General Description

Mnemonic Pin no. Type Name and function

6I/OP3.1 Port 3 bit 1.

I XTAL1 Input to the oscillator circuit and internal clock generator circuits (when

selected via the FLASH configuration). It can be a port pin if internal RC oscillator or watchdog oscillator is used as the CPU clock source, AND if XTAL1/XTAL2 are not used to generate the clock for the real time clock/system timer.

5IGround: 0V reference.

15 I Power Supply: This is the power supply voltage for normal operation as well as

Idle and Power Down modes.

P89LPC920/921/922

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General Description

P89LPC920/921/922

Special Function Registers

Note: Special Function Registers (SFRs) accesses are restricted in the following ways:

1. User must NOT attempt to access any SFR locations not defined.

2. Accesses to any defined SFR locations must be strictly for the functions for the SFRs.

3. SFR bits labeled ’-’, ’0’ or ’1’ can ONLY be written and read as follows:

- ’-’ Unless otherwise specified, MUST be written with ’0’, but can return any value when read (even if it was written with ’0’). It is a reserved bit and may be used in future derivatives.

- ’0’ MUST be written with ’0’, and will return a ’0’ when read.

- ’1’ MUST be written with ’1’, and will return a ’1’ when read

Name Description

ACC* Accumulator E0H 00H 00000000

AUXR1# Auxiliary Function Register A2H CLKLP EBRR ENT1 ENT0 SRST 0 - DPS 00H

B* B Register F0H 00H 00000000

SFR

Address

MSB

E7 E6 E5 E4 E3 E2 E1 E0

F7 F6 F5 F4 F3 F2 F1 F0

Bit Functions and Addresses Reset Value

LSB

Hex Binary

000000x0

BRGR0#§ Baud Rate Generator Rate Low BEH 00H 00000000

BRGR1#§ Baud Rate Generator Rate High BFH 00H 00000000

BRGCON#Baud Rate Generator Control BDH------SBRGSBRGEN00H

CMP1# Comparator 1 Control Register ACH - - CE1 CP1 CN1 OE1 CO1 CMF1 00H

CMP2# Comparator 2 Control Register ADH - - CE2 CP2 CN2 OE2 CO2 CMF2 00H

DIVM# CPU Clock Divide-by-M Control 95H 00H 00000000

DPTR Data Pointer (2 bytes)

DPH Data Pointer High 83H 00H 00000000

DPL Data Pointer Low 82H 00H 00000000

FMADRH# Program Flash Address High E7H 00H 00000000

FMADRL# Program Flash Address Low E6H 00H 00000000

Program Flash Control (Read)

FMCON#

FMDATA# Program Flash Data E5H 00H 00000000

I2ADR# I

I2CON*# I

I2DAT# I

I2SCLH#

Program Flash Control (Write)

C Slave Address Register DBH I2ADR.6 I2ADR.5 I2ADR.4 I2ADR.3 I2ADR.2 I2ADR.1 I2ADR.0 GC 00H 00000000

C Control Register D8H - I2EN STA STO SI AA - CRSEL 00H x00000x0

C Data Register DAH

Serial Clock Generator/SCL Duty Cycle Register High

BUSY - - - HVA HVE SV OI 70H 01110000

E4H

FMCMD.7FMCMD.6FMCMD.5FMCMD.4FMCMD.3FMCMD.2FMCMD.1FMCMD.

DF DE DD DC DB DA D9 D8

DDH 00H 00000000

xxxxxx00

xx000000

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Name Description

I2SCLL#

I2STAT# I

Serial Clock Generator/SCL Duty Cycle Register Low

C Status Register D9H STA.4 STA.3 STA.2 STA.1 STA.0 0 0 0 F8H 11111000

SFR

Address

MSB

Bit Functions and Addresses Reset Value

DCH 00H 00000000

P89LPC920/921/922

LSB

Hex Binary

ICRAH#

AF AE AD AC AB AA A9 A8

IEN0* Interrupt Enable 0 A8H EA EWDRT EBO ES/ESR ET1 EX1 ET0 EX0 00H 00000000

EF EE ED EC EB EA E9 E8

IEN1*# Interrupt Enable 1 E8H - EST - - - EC EKBI EI2C 00H

00x00000

BF BE BD BC BB BA B9 B8

IP0* Interrupt Priority 0 B8H - PWDRT PBO PS/PSR PT1 PX1 PT0 PX0 00H

IP0H# Interrupt Priority 0 High B7H -

PWDRT

PBOH

PSH/

PSRH

PT1H PX1H PT0H PX0H 00H

x0000000

FF FE FD FC FB FA F9 F8

IP1*# Interrupt Priority 1 F8H - PST - - - PC PKBI PI2C 00H

00x00000

IP1H# Interrupt Priority 1 High F7H - PSTH - - - PCH PKBIH PI2CH 00H

KBCON#Keypad Control Register 94H------

PATN_S

KBIF 00H

00x00000

xxxxxx00

KBMASK# Keypad Interrupt Mask Register 86H 00H 00000000

KBPATN# Keypad Pattern Register 93H FFH 11111111

87 86 85 84 83 82 81 80

P0* Port 0 80H T1/KB7

KBI6

CMPREF/

KBI5

CIN1A/

KBI4

CIN1B/

KBI3

CIN2A/

KBI2

CIN2B/

KBI1

CMP2/

KBI0

Note 1

CMP1/

97 96 95 94 93 92 91 90

P1* Port 1 90H - - RST

INT1

INT0/

SDA

T0/SCL RxD TxD Note 1

B7 B6 B5 B4 B3 B2 B1 B0

P3*Port 3 B0H------XTAL1XTAL2Note 1

P0M1# Port 0 Output Mode 1 84H (P0M1.7) (P0M1.6) (P0M1.5) (P0M1.4) (P0M1.3) (P0M1.2) (P0M1.1) (P0M1.0) FFH 11111111

P0M2# Port 0 Output Mode 2 85H (P0M2.7) (P0M2.6) (P0M2.5) (P0M2.4) (P0M2.3) (P0M2.2) (P0M2.1) (P0M2.0) 00H 00000000

P1M1# Port 1 Output Mode 1 91H (P1M1.7) (P1M1.6) - (P1M1.4) (P1M1.3) (P1M1.2) (P1M1.1) (P1M1.0) D3H

P1M2# Port 1 Output Mode 2 92H (P1M2.7) (P1M2.6) - (P1M2.4) (P1M2.3) (P1M2.2) (P1M2.1) (P1M2.0) 00H

P3M1#Port 3 Output Mode 1 B1H------(P3M1.1)(P3M1.0)03H

P3M2#Port 3 Output Mode 2 B2H------(P3M2.1)(P3M2.0)00H

11x11111

00x00000

xxxxxx11

xxxxxx00

PCON# Power Control Register 87H SMOD1 SMOD0 BOPD BOI GF1 GF0 PMOD1 PMOD0 00H 00000000

PCONA# Power Control Register A B5H RTCPD - VCPD I2PD - SPD -

00H

00000000

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General Description

Name Description

PSW* Program Status Wword D0H CY AC F0 RS1 RS0 OV F1 P 00H 00000000

PT0AD# Port 0 Digital Input Disable F6H - - PT0AD.5 PT0AD.4 PT0AD.3 PT0AD.2 PT0AD.1 - 00H xx00000x

RSTSRC# Reset Source Register DFH - - BOF POF R_BK R_WD R_SF R_EX Note 2

RTCCON# Real-Time Clock Control D1H RTCF RTCS1 RTCS0 - - - ERTC RTCEN

RTCH# Real-Time Clock Register High D2H 00H

RTCL# Real-Time Clock Register Low D3H 00H

SADDR# Serial Port Address Register A9H 00H 00000000

SADEN# Serial Port Address Enable B9H 00H 00000000

SBUF Serial Port Data Buffer Register 99H xxH xxxxxxxx

SCON* Serial Port Control 98H SM0/FE SM1 SM2 REN TB8 RB8 TI RI 00H 00000000

SFR

Address

MSB

D7 D6 D5 D4 D3 D2 D1 D0

9F 9E 9D 9C 9B 9A 99 98

Bit Functions and Addresses Reset Value

P89LPC920/921/922

LSB

Hex Binary

60H

011xxx00

00000000

SSTAT# Serial Port Extended Status Register BAH DBMOD INTLO CIDIS DBISEL FE BR OE STINT 00H 00000000

SP Stack Pointer 81H 07H 00000111

TAMOD# Timer 0 and 1 Auxiliary Mode 8FH - - - T1M2 - - - T0M2 00H xxx0xxx0

8F 8E 8D 8C 8B 8A 89 88

TCON* Timer 0 and 1 Control 88H TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 00H 00000000

TH0 Timer 0 High 8CH 00H 00000000

TH1 Timer 1 High 8DH 00H 00000000

TL0 Timer 0 Low 8AH 00H 00000000

TL1 Timer 1 Low 8BH 00H 00000000

TMOD Timer 0 and 1 Mode 89H T1GATE T1C/T T1M1 T1M0 T0GATE T0C/T T0M1 T0M0 00H 00000000

TRIM# Internal Oscillator Trim Register 96H - ENCLK TRIM.5 TRIM.4 TRIM.3 TRIM.2 TRIM.1 TRIM.0 Notes 4,5

WDCON# Watchdog Control Register A7H PRE2 PRE1 PRE0 - - WDRUN WDTOF WDCLK Notes 3,5

WDL# Watchdog Load C1H FFH 11111111

WFEED1# Watchdog Feed 1 C2H

WFEED2# Watchdog Feed 2 C3H

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P89LPC920/921/922

Notes:

* SFRs are bit addressable. # SFRs are modified from or added to the 80C51 SFRs.

- Reserved bits, must be written with 0’s.

§ BRGR1 and BRGR0 must only be written if BRGEN in BRGCON SFR is ’0’. If any of them is written if BRGEN = 1, result is unpredictable. Unimplemented bits in SFRs (labeled ’-’ ) are X (unknown) at all times. Unless otherwise specified, ones should not be written to these bits since

they may be used for other purposes in future derivatives. The reset values shown for these bits are ’0’s although they are unknown when read.

1. All ports are in input only (high impendance) state after power-up.

2. The RSTSRC register reflects the cause of the LPC920/921/922 reset. Upon a power-up reset, all reset source flags are cleared except POF and BOF - the power-on reset value is xx110000.

3. After reset, the value is 111001x1, i.e., PRE2-PRE0 are all 1, WDRUN=1 and WDCLK=1. WDTOF bit is 1 after watchdog reset and is 0 after power-on reset. Other resets will not affect WDTOF.

4. On power-on reset, the TRIM SFR is initialized with a factory preprogrammed value. Other resets will not cause initialization of the TRIM register.

5. The only reset source that affects these SFRs is power-on reset.

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General Description

Memory organization

The P89LPC920/921/922 memory map is shown in Figure 1-1.

FF00h

FFEFh

1FFFh 1E00h

1C00h 1BFFh

1800h 17FFh

1400h

13FFh

1000h

0FFFh

0C00h

0BFFh

0800h 07FFh

0400h

03FFh

0000h

IAP entry-points

ISP CODE (512B)*

Sector 7

Sector 6

Sector 5

Sector 4

Sector 3

Sector 2

Sector 1

Sector 0

Read- protected

IAP calls only

IAP routines

entry points for:

- 51 ASM. code

C code

ISP

serial loader

UART (auto-baud)

-I2C, SPI etc. *

Flexible choices:

- as supplied (UART)

- Phil ips libraries

-user-defined

Note: ISP code is located at the end of Sector

1 on the LPC920, at the end of Sector 4 on the

LPC92 1, AND AT THE END OF Sector 7 on

the LPC922.

P89LPC920/921/922

FFEFh

FF1Fh

FF00h

1FFFh

1E00h

Special Function

Regi sters

(directly addressable)

entry points

I DATA (incl. DATA)

128 Bytes On-Chip Data Memory (stack

and indirect addr. )

DATA

128 Bytes On-Chip

Data Memory (stack,

direct and indir. addr.)

4 Reg. Banks R0-R7

Data Memory

(DATA, IDATA)

Figure 1-1: P89LPC920/921/922 memory map

The various P89LPC920/921/922 memory spaces are as follows:

DATA 128 bytes of internal data memory space (00h..7Fh) accessed via direct or indirect addressing, using instructions

other than MOVX and MOVC. All or part of the Stack may be in this area.

IDATA Indirect Data. 256 bytes of internal data memory space (00h:FFh) accessed via indirect addressing using

instructions other than MOVX and MOVC. All or part of the Stack may be in this area. This area includes the DATA area and the 128 bytes immediately above it.

SFR Special Function Registers. Selected CPU registers and peripheral control and status registers, accessible only via

direct addressing.

CODE 64 KB of Code memory space, accessed as part of program execution and via the MOVC instruction. The

P89LPC920/921/922 has 2 KB/ 4 KB/ 8 KB of on-chip Code memory.).

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P89LPC920/921/922

DATA RAM ARRANGEMENT

The 256 bytes of on-chip RAM is organized as follows:

Type Data RAM Size (Bytes)

DATA Memory that can be addressed directly and indirectly 128

IDATA Memory that can be addressed indirectly (includes DATA) 256

Table 1-1: On-chip data memory usage.

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General Description

P89LPC920/921/922

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CLOCKS

P89LPC920/921/922

2. CLOCKS

Enhanced CPU

The P89LPC920/921/922 uses an enhanced 80C51 CPU which runs at 6 times the speed of standard 80C51 devices. A machine cycle consists of two CPU clock cycles, and most instructions execute in one or two machine cycles.

Clocks

Clock definitions

The P89LPC920/921/922 device has several internal clocks as defined below:

• OSCCLK - Input to the DIVM clock divider. OSCCLK is selected from one of four clock sources (see Figure 2-3) and can also

be optionally divided to a slower frequency (see section "CPU Clock (CCLK) modification: DIVM register").

Note: f

• CCLK - CPU clock; output of the DIVM clock divider. There are two CCLK cycles per machine cycle, and most instructions are

executed in one to two machine cycles (two or four CCLK cycles).

• RCCLK - The internal 7.373 MHz RC oscillator output.

• PCLK - Clock for the various peripheral devices and is CCLK/2.

is defined as the OSCCLK frequency.

OSC

Oscillator clock (OSCCLK)

The P89LPC920/921/922 provides several user-selectable oscillator options. This allows optimization for a range of needs from high precision to lowest possible cost. These options are configured when the FLASH is programmed and include an on-chip watchdog oscillator, an on-chip RC oscillator, an oscillator using an external crystal, or an external clock source. The crystal oscillator can be optimized for low, medium, or high frequency crystals covering a range from 20 kHz to 12 MHz.

Low speed oscillator option

This option supports an external crystal in the range of 20 kHz to 100 kHz. Ceramic resonators are also supported in this configuration.

Medium speed oscillator option

This option supports an external crystal in the range of 100 kHz to 4 MHz. Ceramic resonators are also supported in this configuration.

High speed oscillator option

This option supports an external crystal in the range of 4 MHz to 12 MHz. Ceramic resonators are also supported in this configuration.

Clock output

The P89LPC920/921/922 supports a user-selectable clock output function on the XTAL2 / CLKOUT pin when the crystal oscillator is not being used. This condition occurs if a different clock source has been selected (on-chip RC oscillator,watchdog oscillator, external clock input on X1) and if the Real-time Clock is not using the crystal oscillator as its clock source. This allows external devices to synchronize to the P89LPC920/921/922. This output is enabled by the ENCLK bit in the TRIM register

The frequency of this clock output is 1/2 that of the CCLK. If the clock output is not needed in Idle mode, it may be turned off prior to entering Idle, saving additional power. Note: on reset, the TRIM SFR is initialized with a factory preprogrammed value.

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CLOCKS

P89LPC920/921/922

Therefore when setting or clearing the ENCLK bit, the user should retain the contents of bits 5:0 of the TRIM register. This can be done by reading the contents of the TRIM register (into the ACC for example), modifying bit 6, and writing this result back into the TRIM register. Alternatively,the “ANL direct” or “ORL direct” instructions can be used to clear or set bit 6 of the TRIM register.

Quartz crystal or

ceramic resonator

The oscillator must be configured in one of the following modes:

- Low Frequency Crystal

- Medium Frequency Crystal

- High Frequency Crystal

* A series resistor may be required to limit crystal drive levels. This is especially important for low frequency crystals (see text).

Figure 2-1: Using the crystal oscillator

On-chip RC oscillator option

P89LPC920/921/922

XTAL1

XTAL2

The P89LPC920/921/922 has a 6-bit TRIM register that can be used to tune the frequency of the RC oscillator. During reset, the TRIM value is initialized to a factory pre-programmed value to adjust the oscillator frequency to 7.373 MHz, ±1%. (Note: the initial value is better than 1%; please refer to the datasheet for behavior over temperature). End user applications can write to the TRIM register to adjust the on-chip RC oscillator to other frequencies. Increasing the TRIM value will decrease the oscillator frequency.

TRIM

Address: 96h

Not bit addressable

Reset Source(s): Power-up only

Reset Value: On power-up reset, ENCLK = 0, and TRIM.5-0 are loaded with the factory programmed value.

BIT SYMBOL FUNCTION

TRIM.7 - Reserved.

TRIM.6 ENCLK When ENCLK =1, CCLK/ 2 is output on the XTAL2 pin (P3.0) provided that the crystal

TRIM.5-0 Trim value.

Note: on reset, the TRIM SFR is initialized with a factory preprogrammed value. When setting or clearing the ENCLK bit, the user should retain the contents of bits 5:0 of the TRIM register. This can be done by reading the contents of the TRIM register (into the ACC for example), modifying bit 6, and writing this result back into the TRIM register. Alternatively, the “ANL direct” or “ORL direct” instructions can be used to clear or set bit 6 of the TRIM register.

76543210

- ENCLK TRIM.5 TRIM.4 TRIM.3 TRIM.2 TRIM.1 TRIM.0

oscillator is not being used. When ENCLK=0, no clock output is enabled.

Figure 2-2: On-chip RC oscillator TRIM register

Watchdog oscillator option

The watchdog has a separate oscillator which has a frequency of 400 kHz. This oscillator can be used to save power when a high clock frequency is not needed.

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CLOCKS

P89LPC920/921/922

External clock input option

In this configuration, the processor clock is derived from an external source driving the XTAL1 / P3.1 pin. The rate may be from 0 Hz up to 12 MHz. The XTAL2 / P3.0 pin may be used as a standard port pin or a clock output.

RTCS1:0

XTAL1

XTAL2

RC Oscillator

(7.3728MHz)

Watchdog

Oscillator

High freq.

Med freq.

Low freq.

FOSC2:0

OSC CLK

DIVM

CPU

Clock

CCLK

RTC

CPU

WDT

PCLK

(400KHz)

Baud Rate

Generator

UART

Figure 2-3: Block diagram of oscillator control

Timer 0 & 1

Peripheral Clock

I2C

Oscillator Clock (OSCCLK) wakeup delay

The P89LPC920/921/922 has an internal wakeup timer that delays the clock until it stabilizes depending to the clock source used. If the clock source is any of the three crystal selections, the delay is 992 OSCCLK cycles plus 60-100µs. If the clock source is either the internal RC oscillator or the Watchdog oscillator, the delay is 224 OSCCLK cycles plus 60-100µs.

CPU Clock (CCLK) modification: DIVM register

The OSCCLK frequency can be divided down, by an integer, up to 510 times by configuring a dividing register, DIVM, to provide CCLK. This produces the CCLK frequency using the following formula:

CCLK frequency = f

Where: f

Since N ranges from 0 to 255, the CCLK frequency can be in the range of f

This feature makes it possible to temporarily run the CPU at a lower rate, reducing power consumption. By dividing the clock, the CPU can retain the ability to respond to events other than those that can cause interrupts (i.e. events that allow exiting the Idle mode) by executing its normal program at a lower rate. This can often result in lower power consumption than in Idle mode. This

is the frequency of OSCCLK

OSC

N is the value of DIVM.

OSC

/ (2N)

OSC

to f

/510. (for N =0, CCLK = f

OSC

) .

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CLOCKS

P89LPC920/921/922

can allow bypassing the oscillator start-up time in cases where Power down mode would otherwise be used. The value of DIVM may be changed by the program at any time without interrupting code execution.

Low power select

The P89LPC920/921/922 is designed to run at 12 MHz (CCLK) maximum. However, if CCLK is 8 MHz or slower, the CLKLP SFR bit (AUXR1.7) can be set to a ‘1’ to lower the power consumption further. On any reset, CLKLP is ‘0’ allowing highest performance. This bit can then be set in software if CCLK is running at 8 MHz or slower.

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INTERRUPTS

P89LPC920/921/922

3. INTERRUPTS

The P89LPC920/921/922 uses a four priority level interrupt structure. This allows great flexibility in controlling the handling of the P89LPC920/921/922’s 12 interrupt sources.

Each interrupt source can be individually enabled or disabled by setting or clearing a bit in the interrupt enable registers IEN0 or IEN1. The IEN0 register also contains a global enable bit, EA, which enables all interrupts.

Each interrupt source can be individually programmed to one of four priority levels by setting or clearing bits in the interrupt priority registers IP0, IP0H, IP1, and IP1H. An interrupt service routine in progress can be interrupted by a higher priority interrupt, but not by another interrupt of the same or lower priority. The highest priority interrupt service cannot be interrupted by any other interrupt source. If two requests of different priority levels are received simultaneously, the request of higher priority level is serviced.

If requests of the same priority level are pending at the start of an instruction cycle, an internal polling sequence determines which request is serviced. This is called the arbitration ranking. Note that the arbitration ranking is only used for pending requests of the same priority level.

Table summarizes the interrupt sources, flag bits, vector addresses, enable bits, priority bits, arbitration ranking, and whether each interrupt may wake up the CPU from a Power down mode.

Interrupt priority structure

There are four SFRs associated with the four interrupt levels: IP0, IP0H, IP1, IP1H. Every interrupt has two bits in IPx and IPxH (x = 0,1) and can therefore be assigned to one of four levels, as shown in Table .

Table 3-1: Interrupt priority level

Priority bits

IPxH IPx

0 0 Level 0 (lowest priority)

Interrupt priority level

0 1 Level 1

1 0 Level 2

1 1 Level 3 (highest priority)

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INTERRUPTS

Table 3-2: Summary of interrupts

Description

External Interrupt 0 IE0 0003h EX0 (IEN0.0) IP0H.0, IP0.0 1 (highest) Yes

Timer 0 Interrupt TF0 000Bh ET0 (IEN0.1) IP0H.1, IP0.1 4 No

External Interrupt 1 IE1 0013h EX1 (IEN0.2) IP0H.2, IP0.2 6 Yes

Timer 1 Interrupt TF1 001Bh ET1 (IEN0.3) IP0H.3, IP0.3 8 No

Serial Port Tx and Rx

Serial Port Rx

Brownout Detect BOF 002Bh EBO (IEN0.5) IP0H.5, IP0.5 2 Yes

Watchdog Timer/Realtime Clock

C Interrupt SI 0033h EI2C (IEN1.0) IP1H.0, IP1.0 5 No

KBI Interrupt KBIF 003Bh EKBI (IEN1.1) IP1H.1, IP1.1 7 Yes

Comparators 1/2 interrupt CMF1/CMF2 0043h EC (IEN1.2) IP1H.2, IP1.2 9 Yes

Serial Port Tx

1. SSTAT.5 = 0 selects combined Serial Port (UART) Tx and Rx interrupt; SSTAT.5 = 1 selects Serial Port Rx interrupt only (Tx interrupt will be different, see Note 3 below).

2. This interrupt is used as Serial Port (UART) Tx interrupt if and only if SSTAT.5 = 1, and is disabled otherwise.

3. If SSTAT.0 = 1, the following Serial Port additional flag bits can cause this interrupt: FE, BR, OE

1,3

Interrupt

flag bit(s)

TI & RI

WDOVF/

RTCF

TI 006Bh EST (IEN1.6) P1H.6, IP1.6 10 No

Vector

address

0023h

0053h

Interrupt

enable bit(s)

ES/ESR (IEN0.4)

EWDRT (IEN0.6)

Interrupt

priority

IP0H.4, IP0.4 11 No

IP0H.6, IP0.6 3 Yes

P89LPC920/921/922

Arbitration

ranking

Power down

wakeup

The P89LPC920/921/922 has two external interrupt inputs in addition to the Keypad Interrupt function. The two interrupt inputs are identical to those present on the standard 80C51 microcontrollers.

These external interrupts can be programmed to be level-triggered or edge-triggered by clearing or setting bit IT1 or IT0 in Register TCON. If ITn = 0, external interrupt n is triggered by a low level detected at the INTn is edge triggered. In this mode if consecutive samples of the INTn pin show a high level in one cycle and a low level in the next cycle, interrupt request flag IEn in TCON is set, causing an interrupt request.

Since the external interrupt pins are sampled once each machine cycle, an input high or low level should be held for at least one machine cycle to ensure proper sampling. If the external interrupt is edge-triggered, the external source has to hold the request pin high for at least one machine cycle, and then hold it low for at least one machine cycle. This is to ensure that the transition is detected and that interrupt request flag IEn is set. IEn is automatically cleared by the CPU when the service routine is called.

If the external interrupt is level-triggered, the external source must hold the request active until the requested interrupt is generated. If the external interrupt is still asserted when the interrupt service routine is completed, another interrupt will be generated. It is not necessary to clear the interrupt flag IEn when the interrupt is level sensitive, it simply tracks the input pin level.

If an external interrupt is enabled when the P89LPC920/921/922 is put into Power down or Idle mode, the interrupt occurance will cause the processor to wake up and resume operation. Refer to the section on Power Reduction Modes for details.

pin. If ITn = 1, external interrupt n

External Interrupt pin glitch suppression

Most of the P89LPC920/921/922 pins have glitch suppression circuits to reject short glitches (please refer to the P89LPC920/ 921/922 datasheet, AC Electrical Characteristics for glitch filter specifications) . However, pins SDA/INT0

do not have the glitch suppression circuits. Therefore, INT1

has glitch suppression while INT0 does not.

/P1.3 and SCL/T0/P1.2

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INTERRUPTS

RTCF ERTC

(RTCCON.1)

WDOVF

IE0

EX0

IE1

EX1

BOPD

EBO

KBIF EKBI

EWDRT

CMF2 CMF1

EA (IE0.7)

TF0

ET0

TF1

ET1

TI & RI/RI

ES/ESR

EST

EI2C

P89LPC920/921/922

Wakeup (if in Power down)

Interrupt to CPU

Figure 3-1: Interrupt sources, interrupt enables, and power down wake-up sources

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INTERRUPTS

P89LPC920/921/922

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P89LPC920/921/922

I/O PORTS

4. I/O PORTS

The P89LPC920/921/922 has 3 I/O ports: Port 0, Port 1, and Port 3. Ports 0 and 1 are 8-bit ports and Port 3 is a 2-bit port. The exact number of I/O pins available depends upon the clock and reset options chosen (see Table 4-1)

Table 4-1: .Number of I/O pins available

Clock source Reset option Number of I/O pins

On-chip oscillator or watchdog

oscillator

External clock input

No external reset (except during power-up) 18

External RST

No external reset (except during power-up) 17

External RST

pin supported 17

pin supported 16

Low/medium/high speed oscillator

(external crystal or resonator)

No external reset (except during power-up) 16

External RST

pin supported 15

Port configurations

All but three I/O port pins on the P89LPC920/921/922 may be configured by software to one of four types on a pin-by-pin basis, as shown in Table 4-3. These are: quasi-bidirectional (standard 80C51 port outputs), push-pull, open drain, and input-only. Two configuration registers for each port select the output type for each port pin.

P1.5 (RST) can only be an input and cannot be configured.

P1.2 (SCL/T0) and P1.3 (SDA/INT0) may only be configured to be either input-only or open drain.

Table 4-2: Port output configuration settings

PxM1.y PxM2.y Port output mode

0 0 Quasi-bidirectional

0 1 Push-Pull

1 0 Input Only (High Impedance)

11 Open Drain

Quasi-bidirectional output configuration

Quasi-bidirectional outputs can be used both as an input and output without the need to reconfigure the port. This is possible because when the port outputs a logic high, it is weakly driven, allowing an external device to pull the pin low. When the pin is driven low, it is driven strongly and able to sink a large current. There are three pull-up transistors in the quasi-bidirectional output that serve different purposes.

One of these pull-ups, called the “very weak” pull-up, is turned on whenever the port latch for the pin contains a logic 1. This very weak pull-up sources a very small current that will pull the pin high if it is left floating.

A second pull-up, called the “weak” pull-up, is turned on when the port latch for the pin contains a logic 1 and the pin itself is also at a logic 1 level. This pull-up provides the primary source current for a quasi-bidirectional pin that is outputting a 1. If this pin is pulled low by an external device, the weak pull-up turns off, and only the very weak pull-up remains on. In order to pull the pin low under these conditions, the external device has to sink enough current to overpower the weak pull-up and pull the port pin below its input threshold voltage.

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I/O PORTS

The third pull-up is referred to as the “strong” pull-up. This pull-up is used to speed up low-to-high transitions on a quasibidirectional port pin when the port latch changes from a logic 0 to a logic 1. When this occurs, the strong pull-up turns on for two CPU clocks quickly pulling the port pin high .

The quasi-bidirectional port configuration is shown in Figure 4-1.

Although the P89LPC920/921/922 is a 3 V device most of the pins are 5 V-tolerant. If 5 V is applied to a pin configured in quasibidirectional mode, there will be a current flowing from the pin to VDD causing extra power consumption. Therefore, applying 5 V to pins configured in quasi-bidirectional mode is discouraged.

A quasi-bidirectional port pin has a Schmitt-triggered input that also has a glitch suppression circuit.

(Please refer to the P89LPC920/921/922 datasheet, AC Electrical Characteristics for glitch filter specifications)

port latch data

2 CPU

clock delay

strong

very weak

weak

port pin

input data

Figure 4-1: Quasi-bidirectional output

glitch rejection

Open drain output configuration

The open drain output configuration turns off all pull-ups and only drives the pulldown transistor of the port pin when the port latch contains a logic 0. To be used as a logic output, a port configured in this manner must have an external pull-up, typically a resistor tied to V

The open drain port configuration is shown in Figure 4-2.

An open drain port pin has a Schmitt-triggered input that also has a glitch suppression circuit.

Please refer to the P89LPC920/921/922 datasheet, AC Electrical Characteristics for glitch filter specifications).

. The pulldown for this mode is the same as for the quasi-bidirectional mode.

port latch data

input data

glitch rejection

port pin

Figure 4-2: Open drain output

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I/O PORTS

Input-only configuration

The input port configuration is shown in Figure 4-3. It is a Schmitt-triggered input that also has a glitch suppression circuit.

(Please refer to the P89LPC920/921/922 datasheet, AC Electrical Characteristics for glitch filter specifications)

input data

glitch rejection

Figure 4-3: Input -only

port pin

Push-pull output configuration

The push-pull output configuration has the same pulldown structure as both the open drain and the quasi-bidirectional output modes, but provides a continuous strong pull-up when the port latch contains a logic 1. The push-pull mode may be used when more source current is needed from a port output.

The push-pull port configuration is shown in Figure 4-4.

A push-pull port pin has a Schmitt-triggered input that also has a glitch suppression circuit.

(Please refer to the P89LPC920/921/922 datasheet, AC Electrical Characteristics for glitch filter specifications)

strong

port latch data

port pin

input data

Figure 4-4: Push-pull output

glitch rejection

Port 0 analog functions

The P89LPC920/921/922 incorporates two Analog Comparators. In order to give the best analog performance and minimize power consumption, pins that are being used for analog functions must have both the digital outputs and digital inputs disabled.

Digital outputs are disabled by putting the port pins into the input-only mode as described in the Port Configurations section (see Table 4-3).

Digital inputs on Port 0 may be disabled through the use of the PT0AD register. Bits 1 through 5 in this register correspond to pins P0.1 through P0.5 of Port 0, respectively. Setting the corresponding bit in PT0AD disables that pin’s digital input. Port bits that have their digital inputs disabled will be read as 0 by any instruction that accesses the port.

On any reset, PT0AD bits 1 through 5 default to ‘0’s to enable the digital functions.

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I/O PORTS

Table 4-3: Port output configuration

Port pin

P0.0 P0M1.0 P0M2.0 KBI0,CMP2

P0.1 P0M1.1 P0M2.1 KBI1,CIN2B

P0.2 P0M1.2 P0M2.2 KBI2,CIN2A

P0.3 P0M1.3 P0M2.3 KBI3,CIN1B

P0.4 P0M1.4 P0M2.4 KBI4,CIN1A

P0.5 P0M1.5 P0M2.5 KBI5,CMPREF

P0.6 P0M1.6 P0M2.6 KBI6,CMP1

P0.7 P0M1.7 P0M2.7 KBI7,T1

P1.0 P1M1.0 P1M2.0 TxD

P1.1 P1M1.1 P1M2.1 RxD

P1.2 P1M1.2 P1M2.2 T0,SCL input-only or open-drain

P1.3 P1M1.3 P1M2.3 INT0

P1.4 P1M1.4 P1M2.4 INT1

P1.5 not configurable RST

P1.6 P1M1.6 P1M2.6

P1.7 P1M1.7 P1M2.7

P3.0 P3M1.0 P3M2.0 XTAL2,CLKOUT

P3.1 P3M1.1 P3M2.1 XTAL1

Configuration SFR bits

PxM1.y PxM2.y

Alternate usage Notes

Refer to section "Port 0 analog functions" for usage as

analog inputs (CIN2B, CIN2A, CIN1B, CIN1A and

CMPREF)

,SDA input-only or open-drain

Input only. Usage as general purpose input or RST is

determined by User Configuration Bit RPD (UCFG1.6).

Always a reset input during a power-on sequence.

User’s Manual - Preliminary -

P89LPC920/921/922

Additional port features

After power-up, all pins are in Input-Only mode. Please note that this is different from the LPC76x series of devices.

• After power-up, all I/O pins except P1.5, may be configured by software.

• Pin P1.5 is input only. Pins P1.2 and P1.3 are configurable for either input-only or open drain.

Every output on the P89LPC920/921/922 has been designed to sink typical LED drive current. However, there is a maximum total output current for all ports which must not be exceeded. Please refer to the P89LPC920/921/922 Datasheet for detailed specifications.

All ports pins that can function as an output have slew rate controlled outputs to limit noise generated by quickly switching output signals. The slew rate is factory-set to approximately 10 ns rise and fall times.

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POWER MONITORING FUNCTIONS

5. POWER MONITORING FUNCTIONS

The P89LPC920/921/922 incorporates power monitoring functions designed to prevent incorrect operation during initial poweron and power loss or reduction during operation. This is accomplished with two hardware functions: Power-on Detect and Brownout Detect.

Brownout Detection

The Brownout Detect function determines if the power supply voltage drops below a certain level. The default operation for a Brownout Detection is to cause a processor reset. However, it may alternatively be configured to generate an interrupt by setting the BOI (PCON.4) bit and the EBO (IEN0.5) bit.

Enabling and disabling of Brownout Detection is done via the BOPD (PCON.5) bit, bit field PMOD1-0 (PCON.1-0) and user configuration bit BOE (UCFG1.5). If BOE is in an unprogrammed state, brownout is disabled regardless of PMOD1-0 and BOPD. If BOE is in a programmed state, PMOD1-0 and BOPD will be used to determine whether Brownout Detect will be disabled or enabled. PMOD1-0 is used to select the power reduction mode. If PMOD1-0 = ‘11’, the circuitry for the Brownout Detection is disabled for lowest power consumption. BOPD defaults to ‘0’, indicating brownout detection is enabled on power-on if BOE is programmed.

If Brownout Detection is enabled, the operating voltage range for V VDD falls below the Brownout trip voltage, V If Brownout Detection is disabled, the operating voltage range for VDD is 2.4 V-3.6 V. If the P89LPC920/921/922 device is to operate with a power supply that can be below 2.7 V, BOE should be left in the unprogrammed state so that the device can operate at 2.4 V, otherwise continuous brownout reset may prevent the device from operating.

If Brownout Detect is enabled (BOE programmed, PMOD1-0 ≠ ‘11’, BOPD = 0), BOF (RSTSRC.5) will be set when a brownout is detected, regardless of whether a reset or an interrupt is enabled, . BOF will stay set until it is cleared in software by writing ‘0’ to the bit. Note that if BOE is unprogrammed, BOF is meaningless. If BOE is programmed, and a initial power-on occurs, BOF will be set in addition to the power-on flag (POF - RSTSRC.4).

For correct activation of Brownout Detect, certain V specifications.

(see D.C. Electrical Characteristics), and is negated when VDD rises above VBO.

rise and fall times must be observed. Please see the datasheet for

is 2.7 V-3.6 V, and the brownout condition occurs when

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POWER MONITORING FUNCTIONS

Table 5-1: Brownout options

BOE

(UCFG1.5)

0 (erased)XX XXXX

1 (programmed)

PMOD1-0

(PCON.1-0)

(total power

down)

≠ 11

(any mode

other than

total power

down)

BOPD

(PCON.5)

XXXX

(brownout

detect

powered

down)

(brownout

detect active)

BOI

(PCON.4)

XXX

(brownout

detect

generates

reset)

(brownout

detect

generates

interrupt)

EBO

(IEN0.5)

(enable brownout interrupt)

0 X Both brownout reset and interrupt disabled. V

(IEN0.7)

(global

interrupt

enable)

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P89LPC920/921/922

Description

Brownout disabled. V

Brownout disabled. V However, BOPD is default to ‘0’ upon power-up.

Brownout reset enabled. V

3.6 V. Upon a brownout reset, BOF (RSTSRC.5) will be set to indicate the reset source. BOF can be cleared by writing ‘0’ to the bit.

Brownout interrupt enabled. V

3.6 V. Upon a brownout interrupt, BOF (RSTSRC.5) will be set. BOF can be cleared by writing ‘0’ to the bit.

operating range is 2.4 V-3.6 V. However, BOF (RSTSRC.5) will be set when V Detection trip point. BOF can be cleared by writing ‘0’ to the bit.

operating range is 2.4 V-3.6 V.

operating range is 2.7 V-

falls to the Brownout

Power-on Detection

The Power-On Detect has a function similar to the Brownout Detect, but is designed to work as power initially comes up, before the power supply voltage reaches a level where the Brownout Detect can function. The POF flag (RSTSRC.4) is set to indicate an initial power-on condition. The POF flag will remain set until cleared by software by writing ‘0’ to the bit. Note that if BOE (UCFG1.5) is programmed, BOF (RSTSRC.5) will be set when POF is set. If BOE is unprogrammed, BOF is meaningless.

Power reduction modes

The P89LPC920/921/922 supports three different power reduction modes as determined by SFR bits PCON.1-0 (see Table 5-2):

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P89LPC920/921/922

PMOD1

(PCON.1)

PMOD0

(PCON.0)

0 0 Normal mode (default) - no power reduction.

Idle mode. The Idle mode leaves peripherals running in order to allow them to activate the processor when an interrupt is generated. Any enabled interrupt source or reset may terminate Idle mode.

Power down mode: The Power down mode stops the oscillator in order to minimize power consumption. The P89LPC920/921/922 exits Power down mode via any reset, or certain interrupts - external pins

/INT1, brownout Interrupt, keyboard, Real-time Clock/System Timer), watchdog, and comparator

INT0 trips. Waking up by reset is only enabled if the corresponding reset is enabled, and waking up by interrupt is only enabled if the corresponding interrupt is enabled and the EA SFR bit (IEN0.7) is set. In Power down mode the internal RC oscillator is disabled unless both the RC oscillator has been selected as the system clock AND the RTC is enabled. In Power down mode, the power supply voltage may be reduced to the RAM keep-alive voltage V This retains the RAM contents at the point where Power down mode was entered. SFR contents are not guaranteed after V

has been lowered to V

via Reset in this situation. VDD must be raised to within the operating range before the Power down mode

is exited. When the processor wakes up from Power down mode, it will start the oscillator immediately and begin execution when the oscillator is stable. Oscillator stability is determined by counting 1024 CPU clocks after start-up when one of the crystal oscillator configurations is used, or 256 clocks after start-up for the internal RC or external clock input configurations. Some chip functions continue to operate and draw power during Power down mode, increasing the total power used during Power down. These include:

• Brownout Detect

• Watchdog Timer if WDCLK (WDCON.0) is ‘1’.

• Comparators (Note: Comparators can be powered down separately with PCONA.5 set to ‘1’ and comparators disabled);

• Real-time Clock/System Timer (and the crystal oscillator circuitry if this block is using it, unless RTCPD, i.e., PCONA.7 is ‘1’).

Description

, therefore it is recommended to wake up the processor

RAM

Total power down mode: This is the same as Power down mode except that the Brownout Detection circuitry and the voltage comparators are also disabled to conserve additional power. Note that a brownout reset or interrupt will not occur. Voltage comparator interrupts and Brownout interrupt cannot be used as a wakeup source.The internal RC oscillator is disabled unless both the RC oscillator has been selected as the system clock AND the RTC is enabled.

The following are the wakeup options supported:

• Watchdog Timer if WDCLK (WDCON.0) is ‘1’. Could generate Interrupt or Reset, either one can wake

up the device

• External interrupts INTO/INT1

• Keyboard Interrupt

• Real-time Clock/System Timer (and the crystal oscillator circuitry if this block is using it, unless RTCPD, i.e., PCONA.7 is ‘1’).

• Note: Using the internal RC-oscillator to clock the RTC during Power down may result in relatively high power consumption. Lower power consumption can be achieved by using an external low frequency clock when the Real-time Clock is running during Power down.

Table 5-2: Power reduction modes.

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P89LPC920/921/922

PCON

Address: 87h

Not bit addressable

Reset Source(s): Any reset

Reset Value: 00000000B

BIT SYMBOL FUNCTION

PCON.7 SMOD1 Double Baud Rate bit for the serial port (UART) when Timer 1 is used as the baud rate

PCON.6 SMOD0 Framing Error Location:

PCON.5 BOPD Brownout Detect Power down. When 1, Brownout Detect is powered down and therefore

PCON.4 BOI Brownout Detect Interrupt Enable. When 1, Brownout Detection will generate a interrupt .

PCON.3 GF1 General Purpose Flag 1. May be read or written by user software, but has no effect on

PCON.2 GF0 General Purpose Flag 0. May be read or written by user software, but has no effect on

PCON.1-0 PMOD1-PMOD0 Power Reduction Mode (see section "Power reduction modes").

76543210

SMOD1 SMOD0 BOPD BOI GF1 GF0 PMOD1 PMOD0

source. When 1, the Timer 1 overflow rate is supplied to the UART. When 0, the Timer 1 overflow rate is divided by two before being supplied to the UART. (See Figure 9-2)

-When 0, bit 7 of SCON is accessed as SM0 for the UART.

-When 1, bit 7 of SCON is accessed as the framing error status (FE) for the UART.

This bit also determines the location of the UART receiver interrupt RI (see description on RI in Figure 9-3).

disabled. When 0, Brownout Detect is enabled. (Note: BOPD must be ‘0’ before any programming or erasing commands can be issued. Otherwise these commands will be aborted.)

When 0, Brownout Detection will cause a reset.

operation.

Figure 5-1: Power Control register (PCON)

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POWER MONITORING FUNCTIONS

PCONA

Address: B5H

Not bit addressable

Reset Source(s): Any reset

Reset Value: 00000000B

BIT SYMBOL FUNCTION

PCONA.7 RTCPD Real-time Clock Power down: When ‘1’, the internal clock to the Real-time Clock is

PCONA.6 - Not used. Reserved for future use.

PCONA.5 VCPD Analog Voltage Comparators Power down: When ‘1’, the voltage comparators are

PCONA.4 - Not used. Reserved for future use.

PCONA.3 I2PD I

PCONA.2 - Not used. Reserved for future use.

PCONA.1 SPD Serial Port (UART) Power down: When ‘1’, the internal clock to the UART is disabled. Note

PCONA.0 - Not used. Reserved for future use.

76543210

RTCPD - VCPD - I2PD - SPD -

disabled.

powered down. User must disable the voltage comparators prior to setting this bit.

C Power down: When ‘1’, the internal clock to the I2C is disabled. Note that in either Power down mode or Total Power down mode, the I of this bit.

that in either Power down mode or Total Power down mode, the UART clock will be disabled regardless of this bit.

NOTE: Brownout Detect Power down is located in PCON.5.

C clock will be disabled regardless

Figure 5-2: Power Control register A (PCONA)

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P89LPC920/921/922

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P89LPC920/921/922

RESET

6. RESET

The P1.5/RST pin can function as either an active low reset input or as a digital input, P1.5. The RPE (Reset Pin Enable) bit in UCFG1, when set to 1, enables the external reset input function on P1.5. When cleared, P1.5 may be used as an input pin.

NOTE: During a power-on sequence, The RPE selection is overriden and this pin will always functions as a reset input. An external circuit connected to this pin should not hold this pin low during a Power-on sequence as this will keep the device in reset. After power-on this input will function either as an external reset input or as a digital input as defined by the RPE bit. Only a poweron reset will temporarily override the selection defined by RPE bit. Other sources of reset will not override the RPE bit.

NOTE: During a power cycle, V

must fall below V

reapplied, in order to ensure a power-on reset.

Reset can be triggered from the following sources (see Figure 6-1):

• External reset pin (during power-on or if user configured via UCFG1);

• Power-on Detect;

• Brownout Detect;

• Watchdog Timer;

• Software reset;

• UART break detect reset.

For every reset source, there is a flag in the Reset Register, RSTSRC. The user can read this register to determine the most recent reset source. These flag bits can be cleared in software by writing a ‘0’ to the corresponding bit. More than one flag bit may be set:

• During a power-on reset, both POF and BOF are set but the other flag bits are cleared.

• For any other reset, any previously set flag bits that have not been cleared will remain set.

(see "DC electrical characteristics" in the datasheet) before pwoer is

POR

RPE (UCFG1.6)

RST

WDTE (UCFG1.7)

Watchdog Timer Reset

Software Reset SRST (AUXR1.3)

Power-on Detect

UART Break Detect

EBRR (AUXR1.6)

Brownout Detect Reset

BOPD (PCON.5)

Chip Reset

Figure 6-1: Block diagram of Reset

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P89LPC920/921/922

RESET

RSTSRC

Address: DFH

Not bit addressable

Reset Sources: Power-on only

Reset Value: xx110000B (This is the power-on reset value. Other reset sources will set corresponding bits.)

BIT SYMBOL FUNCTION

RSTSRC.7-6 - Reserved for future use. Should not be set to 1 by user programs.

RSTSRC.5 BOF Brownout Detect Flag. When Brownout Detect is activated, this bit is set. It will remain set

RSTSRC.4 POF Power-on Detect Flag. When Power-on Detect is activated, the POF flag is set to indic ate

RSTSRC.3 R_BK Break detect reset. If a break detect occurs and EBRR (AUXR1.6) is set to ‘1’, a system

RSTSRC.2 R_WD Watchdog Timer reset flag. Cleared by software by writing a ‘0’ to the bit or a Power-on

RSTSRC.1 R_SF Software reset Flag. Cleared by software by writing a ‘0’ to the bit or a Power-on reset.

RSTSRC.0 R_EX External reset Flag. When this bit is ‘1’, it indicates external pin reset. Cleared by software

76543210

- - BOF POF R_BK R_WD R_SF R_EX

until cleared by software by writing a ‘0’ to the bit. (Note: On a Power-on reset, both POF and this bit will be set while the other flag bits are cleared.)

an initial power-up condition. The POF flag will remain set until cleared by software by writing a ‘0’ to the bit.. (Note: On a Power-on reset, both BOF and this bit will be set while the other flag bits are cleared.)

reset will occur. This bit is set to indicate that the system reset is caused by a break detect. Cleared by software by writing a ‘0’ to the bit or on a Power-on reset.

reset.(NOTE: UCFG1.7 must be = 1).

by writing a ‘0’ to the bit or a Power-on reset. If RST reset is over, R_EX will be set.

is still asserted after the Power-on

Figure 6-2: Reset Sources register

Reset vector

Following reset, the P89LPC920//921/922 will fetch instructions from either address 0000h or the Boot address. The Boot address is formed by using the Boot Vector as the high byte of the address and the low byte of the address =00h. The Boot address will be used if a UART break reset occurs or the non-volatile Boot Status bit (BOOTSTAT.0) = 1, or the device has been forced into ISP mode.Otherwise, instructions will be fetched from address 0000H.

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TIMERS 0 AND 1

7. TIMERS 0 AND 1

The P89LPC920/921/922 has two general-purpose counter/timers which are upward compatible with the 80C51 Timer 0 and Timer 1. Both can be configured to operate either as timers or event counters (see Figure 7-1). An option to automatically toggle the Tx pin upon timer overflow has been added.

In the “Timer” function, the timer is incremented every PCLK.

In the “Counter” function, the register is incremented in response to a 1-to-0 transition on its corresponding external input pin (T0 or T1). The external input is sampled once during every machine cycle. When the pin is high during one cycle and low in the next cycle, the count is incremented. The new count value appears in the register during the cycle following the one in which the transition was detected. Since it takes 2 machine cycles (4 CPU clocks) to recognize a 1-to-0 transition, the maximum count rate is 1/4 of the CPU clock frequency. There are no restrictions on the duty cycle of the external input signal, but to ensure that a given level is sampled at least once before it changes, it should be held for at least one full machine cycle.

The “Timer” or “Counter” function is selected by control bits TnC/T Function Register TMOD. Timer 0 and Timer 1 have five operating modes (modes 0, 1, 2, 3 and 6), which are selected by bitpairs (TnM1, TnM0) in TMOD and TnM2 in TAMOD. Modes 0, 1, 2 and 6 are the same for both Timers/Counters. Mode 3 is different. The operating modes are described later in this section.

(x = 0 and 1 for Timers 0 and 1 respectively) in the Special

TMOD

Address: 89h

Not bit addressable

Reset Source(s): Any source

Reset Value: 00000000B

BIT SYMBOL FUNCTION

TMOD.7 T1GATE Gating control for Timer 1. When set, Timer/Counter is enabled only while the INT1

TMOD.6 T1C/T

TMOD.5, 4 T1M1,T1M0 Mode Select for Timer 1.These bits are used with the T1M2 bit in the TAMOD register to

TMOD.3 T0GATE Gating control for Timer 0. When set, Timer/Counter is enabled only while the INT0

TMOD.2 T0C/T

TMOD.1, 0 T0M1,T0M0 Mode Select for Timer 0. These bits are used with the T0M2 bit in the TAMOD register to

Figure 7-1: Timer/Counter Mode Control register (TMOD)

76543210

T1GATE T1C/T

high and the TR1 control pin is set. When cleared, Timer 1 is enabled when the TR1 control bit is set.

Timer or Counter Selector for Timer 1. Cleared for Timer operation (input from CCLK). Set for Counter operation (input from T1 input pin).

determine the Timer 1 mode (see Figure 7-2).

high and the TR0 control pin is set. When cleared, Timer 0 is enabled when the TR0 control bit is set.

Timer or Counter Selector for Timer 0. Cleared for Timer operation (input from CCLK). Set for Counter operation (input from T0 input pin).

determine the Timer 0 mode (see Figure 7-2).

T1M1 T1M0 T0GATE T0C/T T0M1 T0M0

pin is

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TAMOD

Address: 8Fh

Not bit addressable

Reset Source(s): Any reset

Reset Value: xxx0xxx0B

BIT SYMBOL FUNCTION

TAMOD.7-5 - Reserved for future use. Should not be set to 1 by user programs.

TAMOD.4 T1M2 Mode Select bit 2 for Timer 1. It is used with T1M1 and T1M0 in the TMOD register to

TAMOD.3-1 - Reserved for future use. Should not be set to 1 by user programs.

TAMOD.0 T0M2 Mode Select bit 2 for Timer 0. It is used with T0M1 and T0M0 in the TMOD register to

TnM2-TnM0

0 0 0 8048 Timer “TLn” serves as 5-bit prescaler. (Mode 0)

0 0 1 16-bit Timer/Counter “THn” and “TLn” are cascaded; there is no prescaler.(Mode 1)

0 1 0 8-bit auto-reload Timer/Counter. THn holds a value which is loaded into TLn when it

0 1 1 Timer 0 is a dual 8-bit Timer/Counter in this mode. TL0 is an 8-bit Timer/Counter controlled

1 0 0 Reserved. User must not configure to this mode.

1 0 1 Reserved. User must not configure to this mode.

1 1 0 PWM mode (see section "Mode 6").

1 1 1 Reserved. User must not configure to this mode.

76543210

---T1M2---T0M2

determine Timer 1 mode.

determine Timer 0 mode.

Timer Mode

overflows. (Mode 2)

by the standard Timer 0 control bits. TH0 is an 8-bit timer only, controlled by the Timer 1 control bits (see text). Timer 1 in this mode is stopped. (Mode 3)

Figure 7-2: Timer/Counter Auxiliary Mode Control register (TAMOD)

Mode 0

Putting either Timer into Mode 0 makes it look like an 8048 Timer, which is an 8-bit Counter with a divide-by-32 prescaler. Figure 7-4 shows Mode 0 operation.

In this mode, the Timer register is configured as a 13-bit register. As the count rolls over from all 1s to all 0s, it sets the Timer interrupt flag TFn. The count input is enabled to the Timer when TRn = 1 and either TnGATE = 0 or INTn = 1 allows the Timer to be controlled by external input INTn, to facilitate pulse width measurements). TRn is a control bit in the Special Function Register TCON (Figure 7-3). The TnGATE bit is in the TMOD register.

The 13-bit register consists of all 8 bits of THn and the lower 5 bits of TLn. The upper 3 bits of TLn are indeterminate and should be ignored. Setting the run flag (TRn) does not clear the registers.

Mode 0 operation is the same for Timer 0 and Timer 1. See Figure 7-4. There are two different GATE bits, one for Timer 1 (TMOD.7) and one for Timer 0 (TMOD.3).

= 1. (Setting TnGATE

Mode 1

Mode 1 is the same as Mode 0, except that all 16 bits of the timer register (THn and TLn) are used. See Figure 7-5.

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TIMERS 0 AND 1

Mode 2

Mode 2 configures the Timer register as an 8-bit Counter (TLn) with automatic reload, as shown in Figure 7-6. Overflow from TLn not only sets TFn, but also reloads TLn with the contents of THn, which must be preset by software. The reload leaves THn unchanged. Mode 2 operation is the same for Timer 0 and Timer 1.

Mode 3

When Timer 1 is in Mode 3 it is stopped. The effect is the same as setting TR1 = 0.

Timer 0 in Mode 3 establishes TL0 and TH0 as two separate 8-bit counters. The logic for Mode 3 on Timer 0 is shown in Figure 7-7. TL0 uses the Timer 0 control bits: T0C/T, T0GATE, TR0, INT0, and TF0. TH0 is locked into a timer function (counting machine cycles) and takes over the use of TR1 and TF1 from Timer 1. Thus, TH0 now controls the “Timer 1” interrupt.

Mode 3 is provided for applications that require an extra 8-bit timer. With Timer 0 in Mode 3, an P89LPC920/921/922 device can look like it has three Timer/Counters.

Note: When Timer 0 is in Mode 3, Timer 1 can be turned on and off by switching it into and out of its own Mode 3. It can still be used by the serial port as a baud rate generator, or in any application not requiring an interrupt.

Mode 6

In this mode, the corresponding timer can be changed to a PWM with a full period of 256 timer clocks (see Figure 7-8). Its structure is similar to mode 2, except that:

• TFn (n = 0 and 1 for Timers 0 and 1 respectively) is set and cleared in hardware;

• The low period of the TFn is in THn, and should be between 1 and 254, and;

• The high period of the TFn is always 256-THn.

• Loading THn with 00h will force the Tx pin high, loading THn with FFh will force the Tx pin low.

Note that interrupt can still be enabled on the low to high transition of TFn, and that TFn can still be cleared in software like in any other modes.

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TIMERS 0 AND 1

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TCON

Address: 88h

Bit addressable

Reset Source(s): Any reset

Reset Value: 00000000B

BIT SYMBOL FUNCTION

TCON.7 TF1 Timer 1 overflow flag. Set by hardware on Timer/Counter overflow. Cleared by hardware

TCON.6 TR1 Timer 1 Run control bit. Set/cleared by software to turn Timer/Counter 1 on/off.

TCON.5 TF0 Timer 0 overflow flag. Set by hardware on Timer/Counter overflow. Cleared by hardware

TCON.4 TR0 Timer 0 Run control bit. Set/cleared by software to turn Timer/Counter 0 on/off.

TCON.3 IE1 Interrupt 1 Edge flag. Set by hardware when external interrupt 1 edge is detected. Cleared

TCON.2 IT1 Interrupt 1 Type control bit. Set/cleared by software to specify falling edge/low level

TCON.1 IE0 Interrupt 0 Edge flag. Set by hardware when external interrupt 0 edge is detected. Cleared

TCON.0 IT0 Interrupt 0 Type control bit. Set/cleared by software to specify falling edge/low level

76543210

TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

when the interrupt is processed, or by software (except in mode 6, see above, when it is cleared in hardware).

when the processor vectors to the interrupt routine, or by software. (except in mode 6, see above, when it is cleared in hardware)

by hardware when the interrupt is processed, or by software.

triggered external interrupts.

by hardware when the interrupt is processed, or by software.

triggered external interrupts.

PCLK

Tn Pin

INTn

TRn

Gate

Figure 7-3: Timer/Counter Control register (TCON)

C/T

= 0

C/T = 1

Figure 7-4: Timer/Counter 0 or 1 in Mode 0 (13-bit counter)

Control

TLn

(5-bits)

(8-bits)

Overflow

THn

Toggle

TFn

ENTn

Interrupt

Tn Pin

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P89LPC920/921/922

PCLK

Tn Pin

INTn

Tn Pin

INTn

TRn

Gate

PCLK

TRn

Gate

= 0

C/T

= 1

C/T

Figure 7-5: Timer/Counter 0 or 1 in Mode 1 (16-bit counter)

= 0

C/T

C/T = 1

Control

TLn

(8-bits)

TLn

(8-bits)

THn

(8-bits)

Reload

Overflow

THn

Toggle

Overflow

Toggle

TFn

ENTn

TFn

ENTn

Interrupt

Tn Pin

Interrupt

Tn Pin

T0 Pin

INT0

PCLK

TR0

Gate

Figure 7-6: Timer/Counter 0 or 1 in Mode 2 (8-bit auto-reload)

= 0

C/T

= 1

C/T

Osc / 2

TR1

Figure 7-7: Timer/Counter 0 Mode 3 (two 8-bit counters)

Control

TL0

(8-bits)

TH0

(8-bits)

Overflow

Toggle

Overflow

Toggle

TF0

ENT0

(AUXR1.4)

TF1

ENT1

(AUXR1.5)

Interrupt

T0 Pin

(P1.2

open drain )

Interrupt

T1 Pin

(P0.7)

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TIMERS 0 AND 1

C/T

PCLK

TRn

Gate

INTn

Figure 7-8: Timer/Counter 0 or 1 in Mode 6 (PWM auto-reload)

Timer overflow toggle output

Timers 0 and 1 can be configured to automatically toggle a port output whenever a timer overflow occurs. The same device pins that are used for the T0 and T1 count inputs and PWM outputs are also used for the timer toggle outputs. This function is enabled by control bits ENT0 and ENT1 in the AUXR1 register, and apply to Timer 0 and Timer 1 respectively. The port outputs will be a logic 1 prior to the first timer overflow when this mode is turned on.In order for this mode to function, the C/T selecting PCLK as the clock source for the timer.

= 0

Control

TLn

(8-bits)

Reload THn on falling transition

and (256-THn) on rising transition

THn

(8-bits)

Overflow

Toggle

TFn

ENTn

bit must be cleared

Interrupt

Tn Pin

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REAL-TIME CLOCK/SYSTEM TIMER

8. REAL-TIME CLOCK/SYSTEM TIMER

The P89LPC920/921/922 has a simple Real-time Clock/System Timer that allows a user to continue running an accurate timer while the rest of the device is powered down. The Real-time Clock can be an interrupt or a wake-up source (see Figure 8-1). The Real-time Clock is a 23-bit down counter. The clock source for this counter can be either the CPU clock (CCLK) or the XTAL1-2 oscillator, provided that the XTAL1-2 oscillator is not being used as the CPU clock. If the XTAL1-2 oscillator is used as the CPU clock, then the RTC will use CCLK as its clock source regardless of the state of the RTCS1:0 in the RTCCON register. There are three SFRs used for the RTC:

• RTCCON - Real-time Clock control.

• RTCH - Real-time Clock counter reload high (bits 22-15).

• RTCL - Real-time Clock counter reload low (bits 14-7).

Power-On

Reset

RTCH RTCL

RTC Reset

XTAL1XTAL2

Reload on underflow

Low freq.

Med. freq.

MSB

LSB

23-bit down counter

Wake up from

Power-down

Interrupt

if enabled

(shared w. WDT)

The Real-time Clock/System Timer can be enabled by setting the RTCEN (RTCCON.0) bit. The Real-time Clock is a 23-bit down counter (initialized to all 0’s when RTCEN = 0) that is comprised of a 7-bit prescaler and a 16-bit loadable down counter. When RTCEN is written with ‘1’, the counter is first loaded with (RTCH,RTCL,’1111111’) and will count down. When it reaches all 0’s, the counter will be reloaded again with (RTCH,RTCL,’1111111’) and a flag - RTCF (RTCCON.7) - will be set.

Any write to RTCH and RTCL in-between the Real-time Clock reloading will not cause reloading of the counter. When the current count terminates, the contents of RTCH and RTCL will be loaded into the counter and the new count will begin. An immediate reload of the counter can be forced by clearing the RTCEN bit to ‘0’ and then setting it back to ‘1’ .

ERTC

Figure 8-1: Real-time Clock/System Timer block diagram

RTCF

RTC underflow flag

7-bit prescaler

÷ 128

RTCEN

RTC Enable

RTCS1 RTCS2

RTC clk select

High freq.

CCLK

Int. Osc’s

Real-time Clock source

RTCS1-0 (RTCCON.6-5) are used to select the clock source for the RTC if either the Internal RC oscillator or the internal WD oscillator is used as the CPU clock. If the internal crystal oscillator or the external clock input on XTAL1 is used as the CPU clock, then the RTC will use CCLK as its clock source.

Changing RTCS1-0

RTCS1-0 cannot be changed if the RTC is currently enabled (RTCCON.0 =1). Setting RTCEN and updating RTCS1-0 may be done in a single write to RTCCON. However, if RTCEN = 1, this bit must first be cleared before updating RTCS1-0.

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REAL-TIME CLOCK/SYSTEM TIMER

Real-time Clock interrupt/wake up

If ERTC (RTCCON.1), EWDRT (IEN1.0.6) and EA (IEN0.7) are set to ‘1’, RTCF can be used as an interrupt source. This interrupt vector is shared with the watchdog timer. It can also be a source to wake up the device.

Reset sources affecting the Real-time Clock

Only power-on reset will reset the Real-time Clock and its associated SFRs to their default state

Table 8-1: Real-time Clock/System Timer clock sources

RTCS1

(RTCCON.6)

x x 0 0 0 CCLK High frequency crystal

x x 0 0 1 CCLK Medium frequency crystal

x x 0 1 0 CCLK Low frequency crystal

0 1 Medium frequency crystal

1 0 Low frequency crystal

1 1 CCLK

RTCS0

(RTCCON.5)

FOSC2

(UCFG1.2)

011

FOSC1

(UCFG1.1)

FOSC0

(UCFG1.0) RTC clock source CPU clock source

High frequency crystal

Internal RC oscillator

High frequency crystal

0 1 Medium frequency crystal

1 0 Low frequency crystal

1 1 CCLK

x x 1 0 1 undefined undefined

x x 1 1 0 undefined undefined

x x 1 1 1 CCLK External clock input

100

Watchdog oscillator

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REAL-TIME CLOCK/SYSTEM TIMER

RTCCON

Address: D1h

Not bit addressable

Reset Source(s): Power-up only

Reset Value: 011xxx00B

BIT SYMBOL FUNCTION

RTCCON.7 RTCF Real-time Clock Flag. This bit is set to ‘1’ when the 23-bit Real-time Clock reaches a count

of ‘0’. It can be cleared in software.

RTCCON.6-5 RTCS1-0 Real-time Clock source select (see Table 8-1).

RTCCON.4-2 - Reserved for future use. Should not be set to 1 by user programs.

RTCCON.1 ERTC Real-time Clock interrupt enable. The Real-time Clock shares the same interrupt as the

watchdog timer. Note that if the user configuration bit WDTE (UCFG1.7) is ‘0’, the watchdog timer can be enabled to generate an interrupt. Users can read the RTCF (RTCCON.7) bit to determine whether the Real-time Clock caused the interrupt.

RTCCON.0 RTCEN Real-time Clock enable. The Real-time Clock will be enabled if this bit is ‘1’. Note that this

bit will not Power down the Real-time Clock. The RTCPD bit (PCONA.7) if set, will Power down and disable this block regardless of RTCEN.

76543210

RTCF RTCS1 RTCS0 - - - ERTC RTCEN

Figure 8-2: RTCCON Register

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UART

9. UART

The P89LPC920/921/922 has an enhanced UART that is compatible with the conventional 80C51 UART except that Timer 2 overflow cannot be used as a baud rate source. The P89LPC920/921/922 does include an independent Baud Rate Generator. The baud rate can be selected from the oscillator (divided by a constant), Timer 1 overflow, or the independent Baud Rate Generator. In addition to the baud rate generation, enhancements over the standard 80C51 UART include Framing Error detection, break detect, automatic address recognition, selectable double buffering and several interrupt options.

The UART can be operated in 4 modes:

Mode 0

Serial data enters and exits through RxD. TxD outputs the shift clock. 8 bits are transmitted or received, LSB first. The baud rate is fixed at 1/16 of the CPU clock frequency.

Mode 1

10 bits are transmitted (through TxD) or received (through RxD): a start bit (logical 0), 8 data bits (LSB first), and a stop bit (logical

1). When data is received, the stop bit is stored in RB8 in Special Function Register SCON. The baud rate is variable and is determined by the Timer 1 overflow rate or the Baud Rate Generator (see “Baud Rate Generator and selection” section).

Mode 2

11 bits are transmitted (through TxD) or received (through RxD): start bit (logical 0), 8 data bits (LSB first), a programmable 9th data bit, and a stop bit (logical 1). When data is transmitted, the 9th data bit (TB8 in SCON) can be assigned the value of 0 or 1. Or, for example, the parity bit (P, in the PSW) could be moved into TB8. When data is received, the 9th data bit goes into RB8 in Special Function Register SCON and the stop bit is not saved. The baud rate is programmable to either 1/16 or 1/32 of the CCLK frequency, as determined by the SMOD1 bit in PCON.

Mode 3

11 bits are transmitted (through TxD) or received (through RxD): a start bit (logical 0), 8 data bits (LSB first), a programmable 9th data bit, and a stop bit (logical 1). Mode 3 is the same as Mode 2 in all respects except baud rate. The baud rate in Mode 3 is variable and is determined by the Timer 1 overflow rate or the Baud Rate Generator (see “Baud Rate Generator and selection” section).

In all four modes, transmission is initiated by any instruction that uses SBUF as a destination register. Reception is initiated in Mode 0 by the condition RI = 0 and REN = 1. Reception is initiated in the other modes by the incoming start bit if REN = 1.

SFR space

The UART SFRs are at the following locations:

Table 9-1: SFR Locations for UARTs

PCON Power Control 87H

SCON Serial Port (UART) Control 98H

SBUF Serial Port (UART) Data Buffer 99H

SADDR Serial Port (UART) Address A9H

SADEN Serial Port (UART) Address Enable B9H

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SSTAT Serial Port (UART) Status BAH

BRGR1 Baud Rate Generator Rate High Byte BFH

BRGR0 Baud Rate Generator Rate Low Byte BEH

BRGCON Baud Rate Generator Control BDH

Baud Rate Generator and selection

The P89LPC920/921/922 enhanced UART has an independent Baud Rate Generator. The baud rate is determined by a value programmed into the BRGR1 and BRGR0 SFRs. The UART can use either Timer 1 or the baud rate generator output as determined by BRGCON.2-1 (see Figure 9-2). Note that Timer T1 is further divided by 2 if the SMOD1 bit (PCON.7) is set. The independent Baud Rate Generator uses CCLK.

Updating the BRGR1 and BRGR0 SFRs

The baud rate SFRs, BRGR1 and BRGR0 must only be loaded when the Baud Rate Generator is disabled (the BRGEN bit in the BRGCON register is ‘0’). This avoids the loading of an interim value to the baud rate generator. (CAUTION: If either BRGR0

or BRGR1 is written when BRGEN = 1, the result is unpredictable.)

Table 9-2: Baud rate generation for UART

SCON.7

(SM0)

SCON.6

(SM1)

PCON.7

(SMOD1)

BRGCON.1

(SBRGS)

Receive/transmit baud rate for UART

0 0 X X CCLK/16

0 0 CCLK/(256-TH1)64

1 0 CCLK/(256-TH1)32

X 1 CCLK/((BRGR1,BRGR0)+16)

0 X CCLK/32

1 X CCLK/16

0 0 CCLK/(256-TH1)64

1 0 CCLK/(256-TH1)32

X 1 CCLK/((BRGR1,BRGR0)+16)

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UART

BRGCON

Address: BDh

Not bit addressable

Reset Source(s): Any reset

Reset Value: xxxxxx00B

BIT SYMBOL FUNCTION

BRGCON.7-2 - Reserved for future use. Should not be set to 1 by user programs.

BRGCON.1 SBRGS Select Baud Rate Generator as the source for baud rates to UART in modes 1 & 3 (see

BRGCON.0 BRGEN Baud Rate Generator Enable. Enables the baud rate generator. BRGR1 and BRGR0 can

76543210

- - - - - - SBRGS BRGEN

Table 9-2 for details)

only be written when BRGEN =0.

Figure 9-1: BRGCON register

Timer 1 Overflow

(PCLK-based)

Baud Rate Generator

(CCLK-based)

SMOD1 = 1

÷2

SMOD1 = 0

SBRGS = 0

Baud Rate Modes 1 and 3

SBRGS = 1

Figure 9-2: Baud rate generation for UART (Modes 1, 3)

Framing Error

A Framing error occurs when the stop bit is sensed as a logic ‘0’. A Framing error is reported in the status register (SSTAT). In addition, if SMOD0 (PCON.6) is 1, framing errors can be made available in SCON.7. If SMOD0 is 0, SCON.7 is SM0. It is recommended that SM0 and SM1 (SCON.7-6) are programmed when SMOD0 is ‘0’.

Break Detect

A break detect is reported in the status register (SSTAT). A break is detected when any 11 consecutive bits are sensed low. Since a break condition also satisfies the requirements for a framing error, a break condition will also result in reporting a framing error. Once a break condition has been detected, the UART will go into an idle state and remain in this idle state until a stop bit has been received. The break detect can be used to reset the device and force the device into ISP mode by setting the EBRR bit (AUXR1.6)

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UART

SCON

Address: 98h

Bit addressable

Reset Source(s): Any reset

Reset Value: 00000000B

BIT SYMBOL FUNCTION

SCON.7 SM0/FE The use of this bit is determined by SMOD0 in the PCON register. If SMOD0 = 0, this bit

is read and written as SM0, which with SM1, defines the serial port mode. If SMOD0 = 1, this bit is read and written as FE (Framing Error). FE is set by the receiver when an invalid stop bit is detected. Once set, this bit cannot be cleared by valid frames but is cleared by software. (Note: UART mode bits SM0 and SM1 should be programmed when SMOD0 is ‘0’ - default mode on any reset.)

SCON. 6 SM1 With SM0, defines the serial port mode (see table below).

SM0, SM1

0 0 0: shift register CCLK/16 (default mode on any reset)

0 1 1: 8-bit UART Variable (see Table 9-2)

1 0 2: 9-bit UART CCLK/32 or CCLK/16

1 1 3: 9-bit UART Variable (see Table 9-2)

SCON.5 SM2 Enables the multiprocessor communication feature in Modes 2 and 3. In Mode 2 or 3, if

SCON.4 REN Enables serial reception. Set by software to enable reception. Clear by software to disable

SCON.3 TB8 The 9th data bit that will be transmitted in Modes 2 and 3. Set or clear by software as

SCON.2 RB8 The 9th data bit that was received in Modes 2 and 3. In Mode 1 (SM2 must be 0), RB8 is

SCON.1 TI Transmit interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or at the

SCON.0 RI Receive interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or

UART Mode UART 0 Baud Rate

SM2 is set to 1, then Rl will not be activated if the received 9th data bit (RB8) is 0. In Mode 0, SM2 should be 0. In Mode 1, SM2 must be 0.

reception.

desired.

the stop bit that was received. In Mode 0, RB8 is undefined.

the stop bit (see description of INTLO bit in SSTAT register) in the other modes. Must be cleared by software.

approximately halfway through the stop bit time in Mode 1. For Mode 2 or Mode 3, if SMOD0, it is set near the middle of the 9th data bit (bit 8). If SMOD0 = 1, it is set near the middle of the stop bit (see SM2 - SCON.5 - for exceptions). Must be cleared by software.

76543210

SM0/FE SM1 SM2 REN TB8 RB8 TI RI

Figure 9-3: Serial Port Control register (SCON)

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UART

SSTAT

Address: BAh

Not bit addressable

Reset Source(s): Any reset

Reset Value: 00000000B

BIT SYMBOL FUNCTION

SSTAT.7 DBMOD Double buffering mode. When set = 1 enables double buffering. Must be ‘0’ for UART

SSTAT.6 INTLO Transmit interrupt position. When cleared = 0, the Tx interrupt is issued at the beginning

SSTAT.5 CIDIS Combined Interrupt Disable. When set = 1, Rx and Tx interrupts are separate. When

SSTAT.4 DBISEL Double buffering transmit interrupt select. Used only if double buffering is enabled.This bit

SSTAT.3 FE Framing error flag is set when the receiver fails to see a valid STOP bit at the end of the

SSTAT.2 BR Break Detect flag. A break is detected when any 11 consecutive bits are sensed low.

SSTAT.1 OE Overrun Error flag is set if a new character is received in the receiver buffer while it is still

SSTAT.0 STINT Status Interrupt Enable. When set =1, FE, BR, or OE can causean interrupt. The interrupt

76543210

DBMOD INTLO CIDIS DBISEL FE BR OE STINT

mode 0. In order to be compatible with existing 80C51 devices, this bit is reset to ‘0’ to disable double buffering.

of the stop bit. When set =1, the Tx interrupt is issued at end of the stop bit. Must be ‘0’ for mode 0. Note that in the case of single buffering, if the Tx interrupt occurs at the end of a STOP bit, a gap may exist before the next start bit.

cleared = 0, the UART uses a combined Tx/Rx interrupt (like a conventional 80C51 UART). This bit is reset to ‘0’ to select combined interrupts.

controls the number of interrupts that can occur when double buffering is enabled. When set, one transmit interrupt is generated after each character written to SBUF, and there is also one more transmit interrupt generated at the beginning (INTLO = 0) or the end (INTLO = 1) of the STOP bit of the last character sent (i.e., no more data in buffer). This last interrupt can be used to indicate that all transmit operations are over. When cleared = 0, only one transmit interrupt is generated per character written to SBUF. Must be ‘0’ when double buffering is disabled.

Note that except for the first character written (when buffer is empty), the location of the transmit interrupt is determined by INTLO. When the first character is written, the transmit interrupt is generated immediately after SBUF is written.

frame. Cleared by software.

Cleared by software.

full (before the software has read the previous character from the buffer), i.e., when bit 8 of a new byte is received while RI in SCON is still set. Cleared by software.

used (vector address 0023h) is shared with RI (CIDIS = 1) or the combined TI/RI (CIDIS = 0). When cleared = 0, FE, BR, OE cannot cause an interrupt. (Note: FE, BR, or OE is often accompanied by a RI, which will generate an interrupt regardless of the state of STINT). Note that BR can cause a break detect reset if EBRR (AUXR1.6) is set to ‘1’.

Figure 9-4: Serial Port Status register (SSTAT)

More about UART Mode 0

In Mode 0, a write to SBUF will initiate a transmission. At the end of the transmission, TI (SCON.1) is set, which must be cleared in software. Double buffering must be disabled in this mode.

Reception is initiated by clearing RI (SCON.0). Synchronous serial transfer occurs and RI will be set again at the end of the transfer. When RI is cleared, the reception of the next character will begin. Refer to Figure 9-5 for timing.

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Write to SBUF

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S1...S16 S1...S16 S1...S16 S1...S16S1...S16S1...S16 S1...S16 S1...S16 S1...S16 S1...S16S1...S16S1...S16 S1...S16

Shift

RxD (Data Out)

TxD (Shift Clock)

Write to SCON (Clear RI)

Shift

RxD (Data In)

TxD (Shift Clock)

D0 D1 D5D2 D6D3 D4 D7

Transmit

Receive

Figure 9-5: Serial Port Mode 0 (double buffering must be disabled)

More about UART Mode 1

Reception is initiated by detecting a 1-to-0 transition on RxD. RxD is sampled at a rate 16 times the programmed baud rate. When a transition is detected, the divide-by-16 counter is immediately reset. Each bit time is thus divided into 16 counter states. At the 7th, 8th, and 9th counter states, the bit detector samples the value of RxD. The value accepted is the value that was seen in at least 2 of the 3 samples. This is done for noise rejection. If the value accepted during the first bit time is not 0, the receive circuits are reset and the receiver goes back to looking for another 1-to-0 transition. This provides rejection of false start bits. If the start bit proves valid, it is shifted into the input shift register, and reception of the rest of the frame will proceed.

The signal to load SBUF and RB8, and to set RI, will be generated if, and only if, the following conditions are met at the time the final shift pulse is generated: RI = 0 and either SM2=0 or the received stop bit =1. If either of these two conditions is not met, the received frame is lost. If both conditions are met, the stop bit goes into RB8, the 8 data bits go into SBUF, and RI is activated.

TX Clock

Write to SBUF

Shift

TxD

RX Clock

RxD

Shift

÷ 16 Reset

Start Bit Stop Bit

Start Bit

D0 D1 D5D2 D6D3 D4 D7

Figure 9-6: Serial Port Mode 1 (only single transmit buffering case is shown)

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INTLO = 0

Transmit

INTLO = 1

Stop Bit

Receive

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More about UART Modes 2 and 3

Reception is the same as in Mode 1.

The signal to load SBUF and RB8, and to set RI, will be generated if, and only if, the following conditions are met at the time the final shift pulse is generated. (a) RI = 0, and (b) Either SM2 = 0, or the received 9th data bit = 1. If either of these conditions is not met, the received frame is lost, and RI is not set. If both conditions are met, the received 9th data bit goes into RB8, and the first 8 data bits go into SBUF.

TX Clock

Write to SBUF

Shift

TxD

RX Clock

Start Bit Stop Bit

D0 D1 D5D2 D6D3 D4 D7

TB8

INTLO = 0

Transmit

INTLO = 1

RxD

Shift

÷ 16 Reset

Start Bit

D0 D1 D5D2 D6D3 D4 D7

Figure 9-7: Serial Port Mode 2 or 3 (only single transmit buffering case is shown)

Framing Error and RI in Modes 2 and 3 with SM2 = 1

If SM2 = 1 in modes 2 and 3, RI and FE behaves as in the following table.

Table 9-3: FE and RI when SM2 = 1 in Modes 2 and 3

Mode

PCON.6

(SMOD0)

RB8 RI FE

0 No RI when RB8 = 0 Occurs during STOP bit

Similar to Figure 9-7, with SMOD0 = 0, RI

occurs during RB8, one bit before FE

0 No RI when RB8 = 0 Will NOT occur

Similar to Figure 9-7, with SMOD0 = 1, RI

occurs during STOP bit

Stop Bit

RB8

SMOD0 = 0

SMOD0 = 1

Occurs during STOP bit

Receive

Break Detect

. A break is detected when 11 consecutive bits are sensed low and is reported in the status register (SSTAT). For Mode 1, this consists of the start bit, 8 data bits, and two stop bit times. For Modes 2 & 3, this consists of the start bit, 9 data bits, and one stop

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bit. The break detect bit is cleared in software or by a reset. The break detect can be used to reset the device and force the device into ISP mode. This occurs if the UART is enabled and the the EBRR bit (AUXR1.6) is set and a break occurs.

Double buffering

The UART has a transmit double buffer that allows buffering of the next character to be wriiten to SBUF while the first character is being transmitted. Double buffering allows transmission of a string of characters with only one stop bit between any two characters, provided the next character is written between the start bit and the stop bit of the previous character.

Double buffering can be disabled. If disabled (DBMOD, i.e. SSTAT.7 = 0), the UART is compatible with the conventional 80C51 UART. If enabled, the UART allows writing to SnBUF while the previous data is being shifted out.

Double buffering in different modes

Double buffering is only allowed in Modes 1, 2 and 3. When operated in Mode 0, double buffering must be disabled (DBMOD = 0).

Transmit interrupts with double buffering enabled (Modes 1, 2 and 3)

Unlike the conventional UART, when double buffering is enabled, the Tx interrupt is generated when the double buffer is ready to receive new data. The following occurs during a transmission (assuming eight data bits):

1. The double buffer is empty initially.

2. The CPU writes to SBUF.

3. The SBUF data is loaded to the shift register and a Tx interrupt is generated immediately.

4. If there is more data, go to 6, else continue on 5.

5. If there is no more data, then:

- If DBISEL is ‘0’, no more interrupts will occur.

- If DBISEL is ‘1’ and INTLO is ‘0’, a Tx interrupt will occur at the beginning of the STOP bit of the data currently in the shifter (which is also the last data).

- If DBISEL is ‘1’ and INTLO is ‘1’, a Tx interrupt will occur at the end of the STOP bit of the data currently in the shifter (which is also the last data).

6. If there is more data, the CPU writes to SBUF again. Then:

- If INTLO is ‘0’, the new data will be loaded and a Tx interrupt will occur at the beginning of the STOP bit of the data currently in the shifter.

- If INTLO is ‘1’, the new data will be loaded and a Tx interrupt will occur at the end of the STOP bit of the data currently in the shifter.

Go to 3.

Note that if DBISEL is ‘1’ and the CPU is writing to SBUF when the STOP bit of the last data is shifted out, there can be an uncertainty of whether a Tx interrupt is generated already with the UART not knowing whether there is any more data following.

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TxD

Write to

SBUF

Tx Interrupt

TxD

Write to

SBUF

Tx Interrupt

Double Buffering (DBMOD/SSTAT.7 = 1), Early Interrupt (INTLO/SSTAT.6 = 0) is Shown, No End-

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Single Buffering (DBMOD/SSTAT.7 = 0), Early Interrupt (INTLO/SSTAT.6 = 0) is Shown

ing Tx Interrupt (DBISEL/SnSTAT.4 = 0)

TxD

Write to

SBUF

Tx Interrupt

Double Buffering (DBMOD/SSTAT.7 = 1), Early Interrupt (INTLO/SSTAT.6 = 0) is Shown, With

Ending Tx Interrupt (DBISEL/SSTAT.4 = 1)

Figure 9-8: Transmission with and without double buffering

The 9th bit (bit 8) in double buffering (Modes 1, 2 and 3)

If double buffering is disabled (DBMOD, i.e. SSTAT.7 = 0), TB8 can be written before or after SBUF is written, provided TB8 is updated before that TB8 is shifted out. TB8 must not be changed again until after TB8 shifting has been completed, as indicated by the Tx interrupt.

If double buffering is enabled, TB8 MUST be updated before SBUF is written, as TB8 will be double-buffered together with SBUF data. The operation described in the section "Transmit interrupts with double buffering enabled (Modes 1, 2 and 3)" becomes as follows:

1. The double buffer is empty initially.

2. The CPU writes to TB8.

3. The CPU writes to SBUF.

4. The SBUF/TB8 data is loaded to the shift register and a Tx interrupt is generated immediately.

5. If there is more data, go to 7, else continue on 6.

6. If there is no more data, then:

- If DBISEL is ‘0’, no more interrupt will occur.

- If DBISEL is ‘1’ and INTLO is ‘0’, a Tx interrupt will occur at the beginning of the STOP bit of the data currently in the shifter (which is also the last data).

- If DBISEL is ‘1’ and INTLO is ‘1’, a Tx interrupt will occur at the end of the STOP bit of the data currently in the shifter (which is also the last data).

7. If there is more data, the CPU writes to TB8 again.

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8. The CPU writes to SBUF again. Then:

- If INTLO is ‘0’, the new data will be loaded and a Tx interrupt will occur at the beginning of the STOP bit of the data currently in the shifter.

- If INTLO is ‘1’, the new data will be loaded and a Tx interrupt will occur at the end of the STOP bit of the data currently in the shifter.

Go to 4.

Multiprocessor communications

UART modes 2 and 3 have a special provision for multiprocessor communications. In these modes, 9 data bits are received or transmitted. When data is received, the 9th bit is stored in RB8. The UART can be programmed such that when the stop bit is received, the serial port interrupt will be activated only if RB8 = 1. This feature is enabled by setting bit SM2 in SCON. One way to use this feature in multiprocessor systems is as follows:

When the master processor wants to transmit a block of data to one of several slaves, it first sends out an address byte which identifies the target slave. An address byte differs from a data byte in that the 9th bit is 1 in an address byte and 0 in a data byte. With SM2 = 1, no slave will be interrupted by a data byte. An address byte, however, will interrupt all slaves, so that each slave can examine the received byte and see if it is being addressed. The addressed slave will clear its SM2 bit and prepare to receive the data bytes that follow. The slaves that weren’t being addressed leave their SM2 bits set and go on about their business, ignoring the subsequent data bytes.

Note that SM2 has no effect in Mode 0, and must be ‘0’ in Mode 1.

Automatic address recognition

Automatic address recognition is a feature which allows the UART to recognize certain addresses in the serial bit stream by using hardware to make the comparisons. This feature saves a great deal of software overhead by eliminating the need for the software to examine every serial address which passes by the serial port. This feature is enabled by setting the SM2 bit in SCON. In the 9 bit UART modes (mode 2 and mode 3), the Receive Interrupt flag (RI) will be automatically set when the received byte contains either the “Given” address or the “Broadcast” address. The 9 bit mode requires that the 9th information bit is a 1 to indicate that the received information is an address and not data.

Using the Automatic Address Recognition feature allows a master to selectively communicate with one or more slaves by invoking the Given slave address or addresses. All of the slaves may be contacted by using the Broadcast address. Two special Function Registers are used to define the slave’s address, SADDR, and the address mask, SADEN. SADEN is used to define which bits in the SADDR are to be used and which bits are “don’t care”. The SADEN mask can be logically ANDed with the SADDR to create the “Given” address which the master will use for addressing each of the slaves. Use of the Given address allows multiple slaves to be recognized while excluding others. The following examples will help to show the versatility of this scheme:

Slave 0 SADDR = 1100 0000

Slave 1 SADDR = 1100 0000

In the above example SADDR is the same and the SADEN data is used to differentiate between the two slaves. Slave 0 requires a 0 in bit 0 and it ignores bit 1. Slave 1 requires a 0 in bit 1 and bit 0 is ignored. A unique address for Slave 0 would be 1100 0010 since slave 1 requires a 0 in bit 1. A unique address for slave 1 would be 1100 0001 since a 1 in bit 0 will exclude slave 0. Both slaves can be selected at the same time by an address which has bit 0 = 0 (for slave 0) and bit 1 = 0 (for slave 1). Thus, both could be addressed with 1100 0000.

In a more complex system the following could be used to select slaves 1 and 2 while excluding slave 0:

SADEN = 1111 1101 Given = 1100 00X0

SADEN = 1111 1110 Given = 1100 000X

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Slave 0 SADDR = 1100 0000

Slave 1 SADDR = 1110 0000

Slave 2 SADDR = 1110 0000

In the above example the differentiation among the 3 slaves is in the lower 3 address bits. Slave 0 requires that bit 0 = 0 and it can be uniquely addressed by 1110 0110. Slave 1 requires that bit 1 = 0 and it can be uniquely addressed by 1110 and 0101. Slave 2 requires that bit 2 = 0 and its unique address is 1110 0011. To select Slaves 0 and 1 and exclude Slave 2 use address 1110 0100, since it is necessary to make bit 2 = 1 to exclude slave 2. The Broadcast Address for each slave is created by taking the logical OR of SADDR and SADEN. Zeros in this result are treated as don’t-cares. In most cases, interpreting the don’t-cares as ones, the broadcast address will be FF hexadecimal. Upon reset SADDR and SADEN are loaded with 0s. This produces a given address of all “don’t cares” as well as a Broadcast address of all “don’t cares”. This effectively disables the Automatic Addressing mode and allows the microcontroller to use standard UART drivers which do not make use of this feature.

SADEN = 1111 1001 Given = 1100 0XX0

SADEN = 1111 1010 Given = 1110 0X0X

SADEN = 1111 1100 Given = 1110 00XX

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I2C INTERFACE

10. I2C INTERFACE

The I2C-bus uses two wires, serial clock (SCL) and serial data (SDA) to transfer information between devices connected to the bus, and has the following features:

• Bidirectional data transfer between masters and slaves

• Multimaster bus (no central master)

• Arbitration between simultaneously transmitting masters without corruption of serial data on the bus

• Serial clock synchronization allows devices with different bit rates to communicate via one serial bus

• Serial clock synchronization can be used as a handshake mechanism to suspend and resume serial transfer

•The I

A typical I are possible on the I

• Data transfer from a master transmitter to a slave receiver. The first byte transmitted by the master is the slave address. Next

• Data transfer from a slave transmitter to a master receiver. The first byte (the slave address) is transmitted by the master. The

The P89LPC920/921/922 device provides a byte-oriented I Master Receiver Mode, Slave Transmitter Mode and Slave Receiver Mode.

C-bus may be used for test and diagnostic purposes

C-bus configuration is shown in Figure 1. Depending on the state of the direction bit (R/W), two types of data transfers

follows a number of data bytes. The slave returns an acknowledge bit after each received byte.

slave then returns an acknowledge bit. Next follows the data bytes transmitted by the slave to the master. The master returns an acknowledge bit after all received bytes other than the last byte. At the end of the last received byte, a “not acknowledge” is returned. The master device generates all of the serial clock pulses and the START and STOP conditions. A transfer is ended with a STOP condition or with a repeated START condition. Since a repeated START condition is also the beginning of the next serial transfer, the I

C-bus:

C-bus will not be released.

C interface. It has four operation modes: Master Transmitter Mode,

I2C-bus

P1.3/SDA P1.2/SCL

P89LPC920/921/922

The P89LPC920/921/922 CPU interfaces with the I Register), I2DAT (I Cycle Register High Byte), and I2SCLL (SCL Duty Cycle Register Low Byte).

C Data Register), I2STAT (I2C Status Register), I2ADR (I2C Slave Address Register), I2SCLH (SCL Duty

Other Device with I

Interface

Figure 1: I

C-bus through six Special Function Registers (SFRs): I2CON (I2C Control

C-bus configuration

Other Device with I

Interface

SDA

SCL

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I2C INTERFACE

I2C Data register

I2DAT register contains the data to be transmitted or the data received. The CPU can read and write to this 8-bit register while it is not in the process of shifting a byte. Thus this register should only be accessed when the SI bit is set. Data in I2DAT remains stable as long as the SI bit is set. Data in I2DAT is always shifted from right to left: the first bit to be transmitted is the MSB (bit

7), and after a byte has been received, the first bit of received data is located at the MSB of I2DAT.

I2DAT

Address: DAH

Not bit addressable

Reset Source(s): Any reset

Reset Value: 00000000B

I2C Slave Address register

76543210

I2DAT.7 I2DAT.6 I2DAT.5 I2DAT.4 I2DAT.3 I2DAT.2 I2DAT.1 I2DAT.0

Figure 2: I

C Data register

I2ADR register is readable and writable, and is only used when the I2C interface is set to slave mode. In master mode, this register has no effect. The LSB of I2ADR is general call bit. When this bit is set, the general call address (00h) is recognized.

I2ADR

Address: DBH

Not bit addressable

Reset Source(s): Any reset

76543210

I2ADR.6 I2ADR.5 I2ADR.4 I2ADR.3 I2ADR.2 I2ADR.1 I2ADR.0 GC

Reset Value: 00000000B

BIT SYMBOL FUNCTION

I2ADR7, 1 I2ADR.6, 0 7 bit own slave address. When in master mode, the contents of this register has no effect.

I2ADR7.0 GC General call bit. When set, the general call address (00H) is recognized, otherwise it is

ignored.

Figure 3: I

C Slave Address register

I2C Control register

The CPU can read and write this register. There are two bits are affected by hardware: the SI bit and the STO bit. The SI bit is set by hardware and the STO bit is cleared by hardware.

CRSEL determines the SCL source when the I2C is in master mode. In slave mode this bit is ignored and the bus will automatically synchronize with any clock frequency up to 400 kHz from the master I interface uses the Timer1 overflow rate divided by 2 for the I

C clock rate. Timer 1 should be programmed by the user in 8 bit

auto-reload mode (Mode 2).

Data rate of I

If fosc = 12 MHz, reload value is 0 - 255, so I

When CRSEL = 0, the I

C = Timer overflow rate / 2 = PCLK / (2*(256-reload value)),

C data rate range is 11.72 Kbit/sec - 3000 Kbit/sec.

C interface uses the internal clock generator based on the value of I2SCLL and I2CSCLH register. The

duty cycle does not need to be 50%.

C device. When CRSEL = 1, the I2C

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The STA bit is START flag. Setting this bit causes the I2C interface to enter master mode and attempt transmitting a START condition or transmitting a repeated START condition when it is already in master mode.

The STO bit is STOP flag. Setting this bit causes the I2C interface to transmit a STOP condition in master mode, or recovering from an error condition in slave mode.

If the STA and STO are both set, then a STOP condition is transmitted to the I START condition afterwards. If it is in slave mode, an internal STOP condition will be generated, but it is not transmitted to the bus.

I2CON

Address: D8h

Bit addressable

76543210

- I2EN STA STO SI AA - CRSEL

Reset Source(s): Any reset

Reset Value: x00000x0B

BIT SYMBOL FUNCTION

I2CON.7 - Reserved for future use. Should not be set to 1 by user programs.

I2CON.6 I2EN I

C Interface Enable. When set, enables the I2C interface. When clear, the I2C function is

disabled.

I2CON.5 STA Start Flag. STA = 1: I

C enters master mode, checks the bus and generates a START condition if the bus is free. If the bus is not free, it waits for a STOP condition (which will free the bus) and generates a START condition after a delay of a half clock period of the internal clock generator. When the I

is transmitted or received, it transmits a repeated START condition. STA may be set at any time, it may also be set when the I

STA = 0: no START condition or repeated START condition will be generated.

I2CON.4 STO STOP Flag. STO = 1: In master mode, a STOP condition is transmitted to the I

When the bus detects the STOP condition, it will clear STO bit automatically.

In slave mode, setting this bit can recover from an error condition. In this case, no STOP condition is transmitted to the bus. The hardware behaves as if a STOP condition has been received and it switches to “not addressed” Slave Receiver Mode. The STO flag is cleared by hardware automatically.

I2CON.3 SI I

C Interrupt Flag. This bit is set when one of the 25 possible I2C states is entered.

When EA bit and EI2C (IEN1.0) bit are both set, an interrupt is requested when SI is set.. Must be cleared by software by writing 0 to this bit.

I2CON.2 AA The Assert Acknowledge Flag. When set to 1, an acknowledge (low level to SDA) will be

returned during the acknowledge clock pulse on the SCL line on the following situations:

(1)The “own slave address” has been received. (2)The general call address has been received while the general call bit(GC) in I2ADR is set. (3) A data byte has been received while the I while the I

C interface is in the Master Receiver Mode. (4)A data byte has been received

C interface is in the addressed Slave Receiver Mode

When cleared to 0, an not acknowledge (high level to SDA) will be returned during the acknowledge clock pulse on the SCL line on the following situations: (1) A data byte has been received while the I

C interface is in the Master Receiver Mode. (2) A data byte has

been received while the I2C interface is in the addressed Slave Receiver Mode.

I2CON.1 - Reserved for future use. Should not be set to 1 by user programs.

I2CON.0 CRSEL SCL clock selection. When set = 1, Timer1 overflow generates SCL, when cleared = 0,

the internal SCL generator is used base on values of I2SCLH and I2SCLL.

C-bus if it is in master mode, and transmits a

C interface is already in master mode and some data

C interface is in an addressed slave mode.

C-bus.

Figure 4: I

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C Control register

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I2C Status register

This is a read-only register. It contains the status code of I2C interface. The least three bits are always 0. There are 26 possible status codes. When the code is F8H, there is no relevant information available and SI bit is not set. All other 25 status codes correspond to defined I

I2STAT

Address: D9h

Not bit addressable

Reset Source(s): Any reset

Reset Value: 11111000B

BIT SYMBOL FUNCTION

I2STAT7, 3 STA.4, 0 I

I2STAT2, 0 - These three bits are not used and always set to 0.

C states. When any of these states entered, the SI bit will be set. Refer to Table 2 to Table 5 for details.

76543210

STA.4 STA.3 STA.2 STA.1 STA.0 0 0 0

C the status code.

Figure 5: I

C Status register

I2C SCL Duty Cycle registers I2SCLH and I2SCLL

When the internal SCL generator is selected for the I2C interface by setting CRSEL = 0 in the I2CON register, the user must set values for registers I2SCLL and I2SCLH to select the data rate. I2SCLH defines the number of PCLK cycles for SCL = high, I2SCLL defines the number of PCLK cycles for SCL = low. The frequency is determined by the following formula:

Bit Frequency = f

Where f

is the frequency of PCLK.

PCLK

The values for I2SCLL and I2SCLH do not have to be the same; the user can give different duty cycle’s for SCL by setting these two registers. However, the value of the register must ensure that the data rate is in the I the values of I2SCLL and I2SCLH have some restrictions and values for both registers greater than 3 PCLKs are recommended.

Table 1: I

C clock rates selection

I2SCLL

CRSEL 7.373 MHz 3.6865 MHz 1.8433 MHz 12 MHz 6 MHz

I2SCLH

60 - 307 154 - -

70 - 263 132 - -

8 0 - 230 115 - 375

9 0 - 205 102 - 333

10 0 369 184 92 - 300

15 0 246 123 61 400 200

25 0 147 74 37 240 120

30 0 123 61 31 200 100

50 0 74 37 18 120 60

60 0 61 31 15 100 50

/ (2*(I2SCLH + I2SCLL))

PCLK

Bit data rate (Kbit/sec) at f

OSC

C data rate range of 0 - 400 kHz. Thus

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I2C INTERFACE

Table 1: I

C clock rates selection

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Bit data rate (Kbit/sec) at f

I2SCLL

CRSEL 7.373 MHz 3.6865 MHz 1.8433 MHz 12 MHz 6 MHz

I2SCLH

100 0 37 18 9 60 30

150 0 25 12 6 40 20

200 0 18 9 5 30 15

-1

3.6 - 922 Kbps

timer1 in mode2

1.8 - 461 Kbps

timer1 in mode 2

0.9 - 230 Kbps

timer1 in mode 2

OSC

5.86 - 1500 Kbps timer1 in mode 2

2.93 - 750 Kbps

timer1 in mode 2

I2C operation mode

Master Transmitter Mode

In this mode data is transmitted from master to slave. Before the Master Transmitter Mode can be entered, I2CON must be initialized as follows:

76543210

I2CON (D8h)

- I2EN STA STO SI AA - CRSEL

- 1 0 0 0 x - bit rate

Figure 10-6: I

CRSEL defines the bit rate. I2EN must be set to 1 to enable the I2C function. If the AA bit is 0, it will not acknowledge its own slave address or the general call address in the event of another device becoming master of the bus and it can not enter slave mode. STA, STO, and SI bits must be cleared to 0.

The first byte transmitted contains the slave address of the receiving device (7 bits) and the data direction bit. In this case, the data direction bit (R/W) will be logic 0 indicating a write. Data is transmitted 8 bits at a time. After each byte is transmitted, an acknowledge bit is received. START and STOP conditions are output to indicate the beginning and the end of a serial transfer.

C will enter Master Transmitter Mode by setting the STA bit. The I2C logic will send the START condition as soon as the

The I bus is free. After the START condition is transmitted, the SI bit is set, and the status code in I2STAT should be 08h. This status code must be used to vector to an interrupt service routine where the user should load the slave address to I2DAT (Data Register) and data direction bit (SLA+W). The SI bit must be cleared before the data transfer can continue.

When the slave address and R/W bit have been transmitted and an acknowledgment bit has been received, the SI bit is set again, and the possible status codes are 18h, 20h, or 38h for the master mode or 68h, 78h, or 0B0h if the slave mode was enabled (setting AA = Logic 1). The appropriate action to be taken for each of these status codes is shown in Table 2.

C Control register

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S Slave Address R/W A DATA A DATA A/A P

User’s Manual - Preliminary -

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“0” - Write “1” - Read

From Master to Slave From Slave to Master

Figure 7: Format in the Master Transmitter Mode

Data Transferred

(n Bytes + Acknowledge

A = Acknowledge (SDA low) A = Not Acknowledge (SDA high) S = START condition P = STOP Condition

Master Receiver Mode

In the Master Receiver Mode, data is received from a slave transmitter. The transfer started in the same manner as in the Master Transmitter Mode. When the START condition has been transmitted, the interrupt service routine must load the slave address and the data direction bit to I

When the slave address and data direction bit have been transmitted and an acknowledge bit has been received, the SI bit is set, and the Status Register will show the status code. For master mode, the possible status codes are 40H, 48H, or 38H. For slave mode, the possible status codes are 68H, 78H, or B0H. Refer to Table 3 for details.

S Slave Address R A DATA A DATA A P

From Master to Slave From Slave to Master

C Data Register (I2DAT). The SI bit must be cleared before the data transfer can continue.

“0” - Write “1” - Read

Data Transferred

(n Bytes + Acknowledge

A = Acknowledge (SDA low) A = Not Acknowledge (SDA high) S = START condition

Figure 8: Format of Master Receiver Mode

After a repeated START condition, I

C may switch to the Master Transmitter Mode.

S R A SLA A A RS W A A P DATA DATA SLA DATA

Data Transferred

(n Bytes +

Acknowledge

A = Acknowledge (SDA low)

= Not Acknowledge (SDA high)

From Master to Slave From Slave to Master

Figure 9: A Master Receiver switches to Master Transmitter after sending Repeated Start

2003 Nov 6 68

S = START condition P = STOP Condition SLA = Slave Address RS = Repeat START condition

Philips Semiconductors

User’s Manual - Preliminary -

P89LPC920/921/922

I2C INTERFACE

Slave Receiver Mode

In the Slave Receiver Mode, data bytes are received from a master transmitter. To initialize the Slave Receiver Mode, the user should write the slave address to the Slave Address Register (I2ADR) and the I2C Control Register (I2CON) should be configured as follows:

76543210

I2CON (D8h)

CRSEL is not used for slave mode. I2EN must be set = 1 to enable I slave address or the general call address. STA, STO and SI are cleared to 0.

After I2ADR and I2CON are initialized, the interface waits until it is addressed by its own address or general address followed by the data direction bit which is 0(W). If the direction bit is 1(R), it will enter Slave Transmitter Mode. After the address and the direction bit have been received, the SI bit is set and a valid status code can be read from the Status Register(I2STAT). Refer to Table 4 for the status codes and actions.

S Slave Address W A DATA A DATA A /A P/RS

From Master to Slave From Slave to Master

- I2EN STA STO SI AA - CRSEL

-10001 --

Figure 10-10: I2C Control register

C function. AA bit must be set = 1 to acknowledge its own

“0” - Write “1” - Read

Data Transferred

(n Bytes + Acknowledge

A = Acknowledge (SDA low) A = Not Acknowledge (SDA high) S = START condition P = STOP Condition RS = Repeated START condition

Figure 11: Format of Slave Receiver Mode

Slave Transmitter Mode

The first byte is received and handled as in the Slave Receiver Mode. However, in this mode, the direction bit will indicate that the transfer direction is reversed. Serial data is transmitted via P1.3/SDA while the serial clock is input through P1.2/SCL. START and STOP conditions are recognized as the beginning and end of a serial transfer. In a given application, I master and as a slave. In the slave mode, the I2C hardware looks for its own slave address and the general call address. If one of these addresses is detected, an interrupt is requested. When the microcontrollers wishes to become the bus master, the hardware waits until the bus is free before the master mode is entered so that a possible slave action is not interrupted. If bus arbitration is lost in the master mode, I same serial transfer.

2003 Nov 6 69

C switches to the slave mode immediately and can detect its own slave address in the

C may operate as a

Philips Semiconductors

I2C INTERFACE

S Slave Address R A DATA A DATA A P

User’s Manual - Preliminary -

P89LPC920/921/922

“0” - Write “1” - Read

Data Transferred

(n Bytes + Acknowledge

A = Acknowledge (SDA low) From Master to Slave From Slave to Master

A = Not Acknowledge (SDA high)

S = START condition

P = STOP Condition

Figure 12: Format of Slave Transmitter Mode

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I2C INTERFACE

User’s Manual - Preliminary -

P89LPC920/921/922

P1.3/SDA

P1.2/SCL

P1.3

Input Filter

Output

Stage

Input Filter

Output

Stage

P1.2

Timer 1

Overflow

I2CON

I2SCLH

I2SCLL

Address Register

Comparator

Shift Register

Bit Counter / Arbitration &

Sync Logic

Serial Clock

Generator

Control Register & SCL Duty

Cycle Registers

Timing

Control

Logic

I2ADR

ACK

I2DAT

CCLK

Interrupt

Internal Bus

Status Bus

I2STAT

Figure 13: I2C-bus serial interface block diagram

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Status

Decoder

Status Register

Philips Semiconductors

I2C INTERFACE

Table 2: Master Transmitter Mode

User’s Manual - Preliminary -

P89LPC920/921/922

Status

code

(I2STAT)

08H

10H

18h

20h

28h

Status of the

C-bus hardware

A START condition has been transmitted

A repeat START condition has been transmitted

SLA+W has been transmitted; ACK has been received

SLA+W has been transmitted;NOTACK has been received

Data byte in I2DAT has been transmitted; ACK has been received

Application software response

Next action taken by I2C

to/from I2DAT to I2CON

STA STO SI AA

SLA+W will be transmitted; ACK bit will be

Load SLA+W x 0 0 x

Load SLA+W or

Load SLA+R

Load data byte or 0 0 0 x

no I2DAT action or 1 0 0 x Repeated START will be transmitted;

no I2DAT action or

no I2DAT action

Load data byte or 0 0 0 x

no I2DAT action or 1 0 0 x Repeated START will be transmitted;

no I2DAT action or 0 1 0 x

no I2DAT action 1 1 0 x

Load data byte or 0 0 0 x

no I2DAT action or 1 0 0 x Repeated START will be transmitted;

no I2DAT action or 0 1 0 x

no I2DAT action 1 1 0 x

x00x

010x

110x

received

As above;SLA+W will be transmitted;

C switches to Master Receiver Mode

Data byte will be transmitted; ACK bit will be received

STOP condition will be transmitted; STO flag will be reset

STOP condition followed by a START condition will be transmitted; STO flag will be reset.

Data byte will be transmitted;ACK bit will be received

STOP condition will be transmitted; STO flag will be reset

STOP condition followed by a START condition will be transmitted; STO flag will be reset

Data byte will be transmitted; ACK bit will be received

STOP condition will be transmitted; STO flag will be reset

STOP condition followed by a START condition will be transmitted; STO flag will be reset

hardware

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Philips Semiconductors

I2C INTERFACE

Table 2: Master Transmitter Mode(Continued)

User’s Manual - Preliminary -

P89LPC920/921/922

Status

code

(I2STAT)

Status of the

C-bus hardware

Data byte in I2DAT has been transmitted,NOT

30h

ACK hasbeen received

Arbitration lost in

38H

SLA+R/W or data bytes

Table 3: Master Receiver Mode

Status

code

(I2STAT)

Status of the

C-bus hardware

Application software response

Next action taken by I2C

to/from I2DAT to I2CON

hardware

STA STO SI AA

Load data byte or 0 0 0 x

Data byte will be transmitted; ACK bit will be received

no I2DAT action or 1 0 0 x Repeated START will be transmitted;

no I2DAT action or

010x

STOP condition will be transmitted; STO flag will be reset

STOP condition followed by a START

no I2DAT action 1 1 0 x

condition will be transmitted. STO flag will be reset.

No I2DAT action

000x

No I2DAT action 1 0 0 x

C-bus will be released; not addressed

slave will be entered

A START condition will be transmitted when the bus becomes free.

Application software response

Next action taken by I

to/from I2DAT to I2CON

hardware

08H

10H

38H

40h

A START condition has been transmitted

A repeat STARTcondition has been transmitted

Arbitration lost in NOT ACK bit

SLA+R has been transmitted;ACK has been received

STA STO SI AA

SLA+R will be transmitted;

Load SLA+R x 0 0 x

Load SLA+R or

X 0 0 x As above

Load SLA+W x 0 0 x

ACK bit will be received

SLA+W will be transmitted;

I Transmitter Mode

no I2DAT action or

000xI

slave mode

no I2DAT action

100x

A START condition will be transmitted when the bus becomes free

no I2DAT action or0000

no I2DAT action or0001

Data byte will be received; NOT ACK bit will be returned

Data byte will be received; ACK bit will be returned

C will be switches to Master

C will be released; it will enter a

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Philips Semiconductors

I2C INTERFACE

Table 3: Master Receiver Mode(Continued)

User’s Manual - Preliminary -

P89LPC920/921/922

Status

code

(I2STAT)

48h

50h

58h

Status of the

C-bus hardware

SLA+R has been transmitted; NOT ACK has been received

Data byte has been received; ACK has been returned

Data byte has been received; NACK has been returned

Application software response

Next action taken by I2C

to/from I2DAT to I2CON

STA STO SI AA

No I2DAT action or

no I2DAT action or 0 1 0 x

no I2DAT action or 1 1 0 x

Read data byte

read data byte0001

Read data byte or 1 0 0 x Repeated START will be transmitted;

read data byte or 0 1 0 x

read data byte 1 1 0 x

100x

0000

Repeated START will be transmitted;

STOP condition will be transmitted; STO flag will be reset

STOP condition followed by a START condition will be transmitted; STO flag will be reset

Data byte will be received; NOT ACK bit will be returned

Data byte will be received; ACK bit will be returned

STOP condition will be transmitted; STO flag will be reset

STOP condition followed by a START condition will be transmitted; STO flag will be reset

hardware

Table 4: Slave Receiver Mode

Status

code

(I2STAT)

60H

68H

70H

Status of the

C-bus hardware

Own SLA+W has been received; ACK has been received

Arbitration lost in SLA+R/Was master;Own SLA+W has been received, ACK returned

General call address(00H) has beenreceived, ACK has been returned

Application software response

to/from I2DAT to I2CON

STA STO SI AA

no I2DAT action or

no I2DAT action x 0 0 1

No I2DAT action or

no I2DAT action x 0 0 1

No I2DAT action or

no I2DAT action x 0 0 1

x000

Next action taken by I2C

hardware

Data byte will be received and NOT ACK will be returned

Data byte will be received and ACK will be returned

Data byte will be received and NOT ACK will be returned

Data byte will be received and ACK will be returned

Data byte will be received and NOT ACK will be returned

Data byte will be received and ACK will be returned

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Philips Semiconductors

I2C INTERFACE

Table 4: Slave Receiver Mode(Continued)

User’s Manual - Preliminary -

P89LPC920/921/922

Status

code

(I2STAT)

78H

80H

88H

90H

Status of the

C-bus hardware

Arbitration lost in SLA+R/W as master; General call addresshas been received, ACK bit has been returned

Previously addressed with own SLA address; Data has been received; ACK has been returned

Previously

addressed with own

SLA address; Data has been received;

NACK has been

returned

Previously addressed with General call; Datahas been received; ACK has been returned

Application software response

to/from I2DAT to I2CON

STA STO SI AA

no I2DAT action or

no I2DAT action x 0 0 1

Read data byte or

read data byte x 0 0 1

Read data byte or

read data byte

read data byte1001

Read data byte or x 0 0 0

read data byte x 0 0 1

x000

0000

0001

1000

Next action taken by I2C

hardware

Data byte will be received and NOT ACK will be returned

Data byte will be received and ACK will be returned

Data byte will be received and NOT ACK will be returned

Data byte will be received; ACK bit will be returned

Switched to not addressed SLA mode; no recognition of own SLA or general address

Switched to not addressed SLA mode; Own SLA will be recognized; general call address will be recognized if I2ADR.0=1

Switched to not addressed SLA mode; no recognition of own SLA or General call address. A START condition will be transmitted when the bus becomes free

Switched to not addressed SLA mode; Own slave address will be recognized; General call address will be recognized if I2ADR.0=1. A START condition will be transmitted when the bus becomes free.

Data byte will be received and NOT ACK will be returned

Data byte will be received and ACK will be returned

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Philips Semiconductors

I2C INTERFACE

Table 4: Slave Receiver Mode(Continued)

User’s Manual - Preliminary -

P89LPC920/921/922

Status

code

(I2STAT)

98H

A0H

Status of the

C-bus hardware

Previously addressed with General call; Data has been received; NACK has been returned

A STOP condition or repeated START condition has been received while still addressed as SLA/ REC or SLA/TRX

Application software response

to/from I2DAT to I2CON

STA STO SI AA

Read data byte

0000

Switched to not addressed SLA mode; no recognition of own SLA or General call address

Switched to not addressed SLA mode; Own

read data byte

0001

slave address will be recognized; General call address will be recognized if I2ADR.0=1.

Switched to not addressed SLA mode; no recognition of own SLA or General call

read data byte

1000

address. A START condition will be transmitted when the bus becomes free.

Switched to not addressed SLA mode; Own slave address will be recognized; General

read data byte

1001

call address will be recognized if I2ADR.0=1. A START condition will be transmitted when the bus becomes free.

Switched to not addressed SLA mode; no

No I2DAT action 0000

recognition of own SLA or General call address

no I2DAT action

0001

Switched to not addressed SLA mode; Own slave address will be recognized; General call address will be recognized if I2ADR.0=1.

Switched to not addressed SLA mode; no

no I2DAT action

1000

recognition of own SLA or General call address. A START condition will be transmitted when the bus becomes free.

Switched to not addressed SLA mode; Own slave address will be recognized; General

no I2DAT action

1001

call address will be recognized if I2ADR.0=1. A START condition will be transmitted when the bus becomes free.

Next action taken by I2C

hardware

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Philips Semiconductors

I2C INTERFACE

Table 5: Slave Transmitter Mode

User’s Manual - Preliminary -

P89LPC920/921/922

Status

code

(I2STAT)

A8h

B0h

B8H

C0H

Status of the

I2C-bus hardware

Own SLA+R has been received; ACK has been returned

Arbitration lost in SLA+R/W as master; Own SLA+R has been received, ACK has been returned

Data byte in I2DAT has been transmitted; ACK has been received

Data byte in I2DAT has been transmitted; NACK has been received

Application software response

to/from I2DAT to I2CON

STA STO SI AA

Load data byte or x 0 0 0

load data byte x 0 0 1

Load data byte or x 0 0 0

load data byte x 0 0 1

Load data byte or

load data byte

No I2DAT action or

no I2DAT action or0001

no I2DAT action or1000

x000

x001

0000

Last data byte will be transmitted and ACK bit will be received

Data byte will be transmitted; ACK will be received

Last data byte will be transmitted and ACK bit will be received

Data byte will be transmitted; ACK bit will be received

Last data byte will be transmitted and ACK bit will be received

Data byte will be transmitted; ACK will be received

Switched to not addressed SLA mode; no recognition of own SLA or General call address.

Switched to not addressed SLA mode; Own slave address will be recognized; General call address will be recognized if I2ADR.0=1.

Switched to not addressed SLA mode; no recognition of own SLA or General call address. A START condition will be transmitted when the bus becomes free.

Next action taken by I

hardware

no I2DAT action 1001

2003 Nov 6 77

Switched to not addressed SLA mode; Own slave address will be recognized; General call address will be recognized if I2ADR.0=1. A START condition will be transmitted when the bus becomes free.

Philips Semiconductors

I2C INTERFACE

Table 5: Slave Transmitter Mode(Continued)

User’s Manual - Preliminary -

P89LPC920/921/922

Status

code

(I2STAT)

C8H

For more information about the I2C interface, please refer to the I2C specification.

Status of the

C-bus hardware

Last data byte in I2DAT has been transmitted(AA=0); ACK has been received

Application software response

to/from I2DAT to I2CON

STA STO SI AA

No I2DAT action or

no I2DAT action or0001

no I2DAT action or1000

no I2DAT action 1001

0000

Next action taken by I2C

hardware

Switched to not addressed SLA mode; no recognition of own SLA or General call address.

Switched to not addressed SLA mode; Own slave address will be recognized; General call address will be recognized if I2ADR.0=1.

Switched to not addressed SLA mode; no recognition of own SLA or General call address. A START condition will be transmitted when the bus becomes free.

Switched to not addressed SLA mode; Own slave address will be recognized; General call address will be recognized if I2ADR.0=1. A START condition will be transmitted when the bus becomes free.

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User’s Manual - Preliminary -

P89LPC920/921/922

ANALOG COMPARATORS

11. ANALOG COMPARATORS

Two analog comparators are provided on the P89LPC920/921/922. Input and output options allow use of the comparators in a number of different configurations. Comparator operation is such that the output is a logical one (which may be read in a register and/or routed to a pin) when the positive input (one of two selectable pins) is greater than the negative input (selectable from a pin or an internal reference voltage). Otherwise the output is a zero. Each comparator may be configured to cause an interrupt when the output value changes.

Comparator configuration

Each comparator has a control register, CMP1 for comparator 1 and CMP2 for comparator 2. The control registers are identical and are shown in Figure 11-1.

The overall connections to both comparators are shown in Figure 11-2. There are eight possible configurations for each comparator, as determined by the control bits in the corresponding CMPn register: CPn, CNn, and OEn. These configurations are shown in Figure 11-3.

When each comparator is first enabled, the comparator output and interrupt flag are not guaranteed to be stable for 10 microseconds. The corresponding comparator interrupt should not be enabled during that time, and the comparator interrupt flag must be cleared before the interrupt is enabled in order to prevent an immediate interrupt service.

CMPn

Address: ACh (CMP1), ADh (CMP2)

Not bit addressable

Reset Source(s): Any reset

Reset Value: xx000000B

BIT SYMBOL FUNCTION

CMPn.7, 6 - Reserved for future use. Should not be set to 1 by user programs.

CMPn.5 CEn Comparator enable. When set, the corresponding comparator function is enabled.

Comparator output is stable 10 microseconds after CEn is set.

CMPn.4 CPn Comparator positive input select. When 0, CINnA is selected as the positive comparator

input. When 1, CINnB is selected as the positive comparator input.

CMPn.3 CNn Comparator negative input select. When 0, the comparator reference pin CMPREF is

selected as the negative comparator input. When 1, the internal comparator reference, Vref, is selected as the negative comparator input.

CMPn.2 OEn Output enable. When 1, the comparator output is connected to the CMPn pin if the

comparator is enabled (CEn = 1). This output is asynchronous to the CPU clock.

CMPn.1 COn Comparator output, synchronized to the CPU clock to allow reading by software.

CMPn.0 CMFn Comparator interrupt flag. This bit is set by hardware whenever the comparator output

COn changes state. This bit will cause a hardware interrupt if enabled. Cleared by software.

Figure 11-1: Comparator control registers (CMP1 and CMP2)

76543210

- - CEn CPn CNn OEn COn CMFn

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ANALOG COMPARATORS

User’s Manual - Preliminary -

P89LPC920/921/922

(P0.4) CIN1A

(P0.3) CIN1B

(P0.5) CMPREF

(P0.2) CIN2A

(P0.1) CIN2B

Vref

CP1

Comparator 1

OE1

CO1

Change Detect

CN1

CP2

Change Detect

Comparator 2

CMF1

CMF2

CO2

OE2

CN2

Figure 11-2: Comparator input and output connections

CMP1 (P0.6)

Interrupt

CMP2 (P0.0)

Internal reference voltage

An internal reference voltage, Vref, may supply a default reference when a single comparator input pin is used. Please refer to the Datasheet for specifications.

Comparator interrupt

Each comparator has an interrupt flag CMFn contained in its configuration register. This flag is set whenever the comparator output changes state. The flag may be polled by software or may be used to generate an interrupt. The two comparators use one common interrupt vector. The interrupt will be generated when the interrupt enable bit EC in the IEN1 register is set and the interrupt system is enabled via the EA bit in the IEN0 register. If both comparators enable interrupts, after entering the interrupt service routine, the user will need to read the flags to determine which comparator caused the interrupt.

When a comparator is disabled the comparator’s output, COx, goes high. If the comparator output was low and then is disabled, the resulting transition of the comparator output from a low to high state will set the the comparator flag, CMFx. This will cause an interrupt if the comparator interrupt is enabled. The user should therefore disable the comparator interrupt prior to disabling the comparator. Additionally, the user should clear the comparator flag, CMFx, after disabling the comparator.

Comparators and power reduction modes

Either or both comparators may remain enabled when Power down or Idle mode is activated, but both comparators are disabled automatically in Total Power down mode.

If a comparator interrupt is enabled (except in Total Power down mode), a change of the comparator output state will generate an interrupt and wake up the processor. If the comparator output to a pin is enabled, the pin should be configured in the pushpull mode in order to obtain fast switching times while in Power down mode. The reason is that with the oscillator stopped, the temporary strong pull-up that normally occurs during switching on a quasi-bidirectional port pin does not take place.

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User’s Manual - Preliminary -

P89LPC920/921/922

ANALOG COMPARATORS

Comparators consume power in Power down and Idle modes, as well as in the normal operating mode. This should be taken into consideration when system power consumption is an issue. To minimize power consumption, the user can Power down the comparators by disabling the comparators and setting PCONA.5 to ‘1’, or simply putting the device in Total Power down mode.

CPn, CNn, OEn = 0 0 0

CINnA

CMPREF

CPn, CNn, OEn = 0 1 0

CINnA

Vref (1.23V)

CPn, CNn, OEn = 1 0 0

CINnB

CMPREF

CPn, CNn, OEn = 1 1 0

CINnB

Vref (1.23V)

CPn, CNn, OEn = 0 0 1

COn

CINnA

CMPREF

CPn, CNn, OEn = 0 1 1

CINnA

Vref (1.23V)

CPn, CNn, OEn = 1 0 1

CINnB

CMPREF

CPn, CNn, OEn = 1 1 1

CINnB

Vref (1.23V)

COn

CMPn

COn

CMPn

COn

CMPn

COn

CMPn

Figure 11-3: Comparator configurations

Comparator configuration example

The code shown below is an example of initializing one comparator. Comparator 1 is configured to use the CIN1A and CMPREF inputs, outputs the comparator result to the CMP1 pin, and generates an interrupt when the comparator output changes.

CMPINIT:

MOV PT0AD,#030h ; Disable digital INPUTS on pins that are used for analog functions: CIN1A, CMPREF.

ANL P0M2,#0CFh ; Disable digital OUTPUTS on pins that are used

ORL P0M1,#030h ; for analog functions: CIN1A, CMPREF.

MOV CMP1,#024h ; Turn on comparator 1 and set up for:

; - Positive input on CIN1A.

; - Negative input from CMPREF pin.

; - Output to CMP1 pin enabled.

CALL delay10us ; The comparator has to start up for at least 10 microseconds before use.

ANL CMP1,#0FEh ; Clear comparator 1 interrupt flag.

SETB EC ; Enable the comparator interrupt. The priority is left at the current value.

SETB EA ; Enable the interrupt system (if needed).

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P89LPC920/921/922

ANALOG COMPARATORS

RET ; Return to caller.

The interrupt routine used for the comparator must clear the interrupt flag (CMF1 in this case) before returning.

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P89LPC920/921/922

KEYPAD INTERRUPT (KBI)

12. KEYPAD INTERRUPT (KBI)

The Keypad Interrupt function is intended primarily to allow a single interrupt to be generated when Port 0 is equal to or not equal to a certain pattern. This function can be used for bus address recognition or keypad recognition. The user can configure the port via SFRs for different tasks.

There are three SFRs used for this function. The Keypad Interrupt Mask Register (KBMASK) is used to define which input pins connected to Port 0 are enabled to trigger the interrupt. The Keypad Pattern Register (KBPATN) is used to define a pattern that is compared to the value of Port 0. The Keypad Interrupt Flag (KBIF) in the Keypad Interrupt Control Register (KBCON) is set when the condition is matched while the Keypad Interrupt function is active. An interrupt will be generated if it has been enabled by setting the EKBI bit in IEN1 register and EA = 1. The PATN_SEL bit in the Keypad Interrupt Control Register (KBCON) is used to define equal or not-equal for the comparison.

In order to use the Keypad Interrupt as an original KBI function like in the 87LPC76x series, the user needs to set KBPATN = 0FFH and PATN_SEL = 0 (not equal), then any key connected to Port0 which is enabled by KBMASK register is will cause the hardware to set KBIF = 1 and generate an interrupt if it has been enabled. The interrupt may be used to wake up the CPU from Idle or Power down modes. This feature is particularly useful in handheld, battery powered systems that need to carefully manage power consumption yet also need to be convenient to use.

In order to set the flag and and cause an interrupt, the pattern on Port 0 must be held longer than 6 CCLKs.

KBPATN

Address: 93h

Not bit addressable

Reset Source(s): Any reset

Reset Value: 11111111B

BIT SYMBOL FUNCTION

KBPATN.7-0 - Pattern bit 7 - bit 0

KBCON

Address: 94h

Not bit addressable

Reset Source(s): Any reset

Reset Value: xxxxxx00B

BIT SYMBOL FUNCTION

KBCON.7-2 - Reserved

KBCON.1 PATN_SEL Pattern Matching Polarity selection. When set, Port 0 has to be equal to the user-defined

KBCON.0 KBIF Keypad Interrupt Flag. Set when Port 0 matches user defined conditions specified in

76543210

KBPATN.7 KBPATN.6 KBPATN.5 KBPATN.4 KBPATN.3 KBPATN.2 KBPATN.1 KBPATN.0

Figure 12-1: Keypad Pattern register

76543210

------PATN_SEL KBIF

Pattern in KBPATN to generate the interrupt. When clear, Port 0 has to be not equal to the value of KBPATN register to generate the interrupt.

KBPATN, KBMASK, and PATN_SEL. Needs to be cleared by software by writing “0”.

Figure 12-2: Keypad Control register

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KEYPAD INTERRUPT (KBI)

User’s Manual - Preliminary -

P89LPC920/921/922

KBMASK

Address: 86h

Not bit addressable

Reset Source(s): Any reset

Reset Value: 00000000B

BIT SYMBOL FUNCTION

KBMASK.7 - When set, enables P0.7 as a cause of a Keypad Interrupt.

KBMASK.6 - When set, enables P0.6 as a cause of a Keypad Interrupt.

KBMASK.5 - When set, enables P0.5 as a cause of a Keypad Interrupt.

KBMASK.4 - When set, enables P0.4 as a cause of a Keypad Interrupt.

KBMASK.3 - When set, enables P0.3 as a cause of a Keypad Interrupt.

KBMASK.2 - When set, enables P0.2 as a cause of a Keypad Interrupt.

KBMASK.1 - When set, enables P0.1 as a cause of a Keypad Interrupt.

KBMASK.0 - When set, enables P0.0 as a cause of a Keypad Interrupt.

Note: the Keypad Interrupt must be enabled in order for the settings of the KBMASK register to be effective.

76543210

KBMASK.7 KBMASK.6 KBMASK.5 KBMASK.4 KBMASK.3 KBMASK.2 KBMASK.1 KBMASK.0

Figure 12-3: Keypad Interrupt Mask register (KBM)

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WATCHDOG TIMER

13. WATCHDOG TIMER

The watchdog timer subsystem protects the system from incorrect code execution by causing a system reset when it underflows as a result of a failure of software to feed the timer prior to the timer reaching its terminal count. The watchdog timer can only be reset by a power-on reset.

Watchdog Function

The user has the ability using the WDCON and UCFG1 registers to control the run /stop condition of the WDT, the clock source for the WDT, the prescaler value, and whether the WDT is enabled to reset the device on underflow. In addition, there is a safety mechanism which forces the WDT to be enabled by values programmed into UCFG1 either through IAP or a commercial programmer.

The WDTE bit (UCFG1.7), if set, enables the WDT to reset the device on underflow. Following reset, the WDT will be running regardless of the state of the WDTE bit.

The WDRUN bit (WDCON.2) can be set to start the WDT and cleared to stop the WDT. Following reset this bit will be set and the WDT will be running. All writes to WDCON need to be followed by a feed sequence (see section "Feed Sequence" on page

86). Additional bits in WDCON allow the user to select the clocksource for the WDT and the prescaler.

When the timer is not enabled to reset the device on underflow, the WDT can be used in "timer mode" and be enabled to produce an interrupt (IEN0.6) if desired.

The Watchdog Safety Enable bit, WDSE (UCFG1.4) along with WDTE, is designed to force certain operating conditions at powerup. Refer to the Table 13-1 for details

Table 13-1: Watchdog timer configuration.

WDTE

(UCFG1.7)

WDSE

(UCFG1.4)

FUNCTION

The watchdog reset is disabled. The timer can be used as an internal timer and can be used to generate an interrupt. WDSE has no effect.

Figure 13-3 shows the watchdog timer in watchdog mode. It consists of a programmable 13-bit prescaler, and an 8-bit down counter. The down counter is clocked (decremented) by a tap taken from the prescaler. The clock source for the prescaler is either PCLK or the watchdog oscillator selected by the WDCLK bit in the WDCON register. (Note that switching of the clock sources will not take effect immediately - see section "Watchdog Clock Source" on page 88).

The watchdog asserts the watchdog reset when the watchdog count underflows and the watchdog reset is enabled. When the watchdog reset is enabled, writing to WDL or WDCON must be followed by a feed sequence for the new values to take effect.

If a watchdog reset occurs, the internal reset is active for at least one watchdog clock cycle (PCLK or the watchdog oscillator clock). If CCLK is still running, code execution will begin immediately after the reset cycle. If the processor was in Power down mode, the watchdog reset will start the oscillator and code execution will resume after the oscillator is stable.

The watchdog reset is enabled. The user can set WDCLK to choose the clock source.

The watchdog reset is enabled, along with additional safety features:

1. WDCLK is forced to 1 (using watchdog oscillator)

2. WDCON and WDL register can only be written once

3. WDRUN is forced to 1

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WATCHDOG TIMER

Watchdog Oscillator

PCLK

WDCLK after a

watchdog feed

sequence

PRE2

PRE1

PRE0

Feed Sequence

DECODE

÷32

÷32 ÷64 ÷128 ÷256 ÷512 ÷1024 ÷2048 ÷4096

000 001

010 011

100 101

110

111

÷2 ÷2 ÷2 ÷2 ÷2 ÷2 ÷2

Figure 13-1: Watchdog Prescaler

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TO WATCHDOG DOWN COUNTER (after one prescaler count delay

The watchdog timer control register and the 8-bit down counter (Figure 13-3) are not directly loaded by the user. The user writes to the WDCON and the WDL SFRs. At the end of a feed sequence, the values in the WDCON and WDL SFRs are loaded to the control register and the 8-bit down counter. Before the feed sequence, any new values written to these two SFRs will not take effect. To avoid a watchdog reset, the watchdog timer needs to be fed (via a special sequence of software action called the feed sequence) prior to reaching an underflow.

To feed the watchdog, two write instructions must be sequentially executed successfully. Between the two write instructions, SFR reads are allowed, but writes are not allowed. The instructions should move A5H to the WFEED1 register and then 5AH to the WFEED2 register. An incorrect feed sequence will cause an immediate watchdog reset. The program sequence to feed the watchdog timer is as follows:

CLR EA ; disable interrupt

MOV WFEED1,#0A5h ; do watchdog feed part 1

MOV WFEED2,#05Ah ; do watchdog feed part 2

SETB EA ; enable interrupt

This sequence assumes that the P89LPC901/902/903 interrupt system is enabled and there is a possibility of an interrupt request occuring during the feed sequence. If an interrupt was allowed to be serviced and the service routine contained any SFR writes, it would trigger a watchdog reset. If it is known that no interrupt could occur during the feed sequence, the instructions to disable and re-enable interrupts may be removed.

In watchdog mode (WDTE = 1), writing the WDCON register must be IMMEDIATELY followed by a feed sequence to load the WDL to the 8-bit down counter, and the WDCON to the shadow register. If writing to the WDCON register is not immediately followed by the feed sequence, a watchdog reset will occur.

For example: setting WDRUN = 1:

MOV ACC,WDCON ; get WDCON

SETB ACC.2 ; set WD_RUN=1

MOV WDL,#0FFh ; New count to be loaded to 8-bit down counter

CLR EA ; disable interrupt

MOV WDCON,ACC ; write back to WDCON (after the watchdog is enabled, a feed must occur

; immediately)

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MOV WFEED1,#0A5h ; do watchdog feed part 1

MOV WFEED2,#05Ah ; do watchdog feed part 2

SETB EA ; enable interrupt

In timer mode (WDTE = 0), WDCON is loaded to the control register every CCLK cycle (no feed sequence is required to load the control register), but a feed sequence is required to load from the WDL SFR to the 8-bit down counter before a time-out occurs.

WDCON

Address: A7h

Not bit addressable

Reset Source(s): See reset value below

Reset Value: 111xx1?1B (Note: WDCON.7,6,5,2,0 - set to ’1’ any reset; WDCON.1 - cleared to ’0’ on Power-on

BIT SYMBOL FUNCTION

WDCON.7-5 PRE2-PRE0 Clock Prescaler Tap Select. Refer to Table 13-2 for details.

WDCON.4-3 - Reserved for future use. Should not be set to 1 by user program.

WDCON.2 WDRUN Watchdog Run Control. The watchdog timer is started when WDRUN = 1 and stopped

WDCON.1 WDTOF Watchdog Timer Time-Out Flag. This bit is set when the 8-bit down counter underflows.

WDCON.0 WDCLK Watchdog input clock select. When set, the watchdog oscillator is selected. When cleared,

76543210

PRE2 PRE1 PRE0 - - WDRUN WDTOF WDCLK

reset, set to ’1’ on watchdog reset, not affected by any other reset)

when WDRUN = 0. This bit is forced to 1 (watchdog running) and cannot be cleared to zero if both WDTE and WDSE are set to 1.

In watchdog mode, a feed sequence will clear this bit. It can also be cleared by writing ’0’ to this bit in software.

PCLK is selected. (If the CPU is powered down, the watchdog is disabled if WDCLK = 0, see section "Power down operation"). (Note: If both WDTE and WDSE are set to 1, this bit is forced to 1.) Refer to section "Watchdog Clock Source" on page 88 for details.

Figure 13-2: Watchdog Timer Control Register

The number of watchdog clocks before timing out is calculated by the following equations:

(5+PRE)

tclks = (2

where:

• PRE is the value of prescaler (PRE2-PRE0) which can be the range 0-7, and;

• WDL is the value of watchdog load register which can be the range of 0-255.

The minimum number of tclks is:

tclks = (2

The maximum number of tclks is:

tclks = (2

The following table show sample P89LPC920/921/922 timeout values

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)(WDL+1)+1

(5+0)

)(0+1)+1 = 33

(5+7)

)(255+1)+1 = 1,048,577T

Philips Semiconductors

WATCHDOG TIMER

Table 13-2: P89LPC920/921/922 Watchdog Timeout Values.

Timeout Period

PRE2-PRE0 WDL in decimal)

000

001

010

011

100

101

110

111

0 33 82.5µs 5.50µs

255 8,193 20.5ms 1.37ms

0 65 162.5µs 10.8µs

255 16,385 41.0ms 2.73ms

0 129 322.5µs 21.5µs

255 32,769 81.9ms 5.46ms

0 257 642.5µs 42.8µs

255 65,537 163.8ms 10.9ms

0 513 .1.28ms 85.5µs

255 131,073 327.7ms 21.8ms

0 1,025 2.56ms 170.8µs

255 262,145 655.4ms 43.7ms

0 2,049 5.12ms 341.5µs

255 524,289 1.31s 87.4ms

0 4097 10.2ms 682.8µs

255 1,048,577 2.62s 174.8ms

(in watchdog clock

cycles)

400KHz Watchdog Oscillator Clock

(Nominal)

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Watchdog Clock Source

12MHz CCLK (6MHz CCLK/2

Watchdog Clock)

Watchdog Clock Source

The watchdog timer system has an on-chip 400KHz oscillator. The watchdog timer can be clocked from either the watchdog oscillator or from PCLK (refer to Figure 13-1) by configuring the WDCLK bit in the Watchdog Control Register WDCON. When the watchdog feature is enabled, the timer must be fed regularly by software in order to prevent it from resetting the CPU.

After changing WDCLK (WDCON.0), switching of the clock source will not immediately take effect. As shown in Figure 13-3, the selection is loaded after a watchdog feed sequence. In addition, due to clock synchronization logic, it can take two old clock cycles before the old clock source is deselected, and then an additional two new clock cycles before the new clock source is selected.

Since the prescaler starts counting immediately after a feed, switching clocks can cause some inaccuracy in the prescaler count. The inaccuracy could be as much as 2 old clock source counts plus 2 new clock cycles.

Note: When switching clocks, it is important that the old clock source is left enabled for 2 clock cycles after the feed completes. Otherwise, the watchdog may become disabled when the old clock source is disabled. For example, suppose PCLK (WCLK=0) is the current clock source. After WCLK is set to ’1’, the program should wait at least two PCLK cycles (4 CCLKs) after the feed completes before going into Power down mode. Otherwise, the watchdog could become disabled when CCLK turns off. The watchdog oscillator will never become selected as the clock source unless CCLK is turned on again first.

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WATCHDOG TIMER

MOV WFEED1, #0A5H MOV WFEED2, #05AH

Watchdog

Oscillator

PCLK

÷32

PRESCALER

control register

WDL (C1H)

8-Bit Down

Counter

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Watchdog reset can also be caused

by an invalid feed sequence, or by

writing to WDCON not immediately

followed by a feed sequence

RESET

SHADOW

WDCON

PRE2 PRE1 PRE0 WDRUN WDTOF WDCLK

WDCON(A7H)

Figure 13-3: Watchdog Timer in Watchdog Mode (WDTE = 1)

Watchdog Timer in Timer Mode

Figure 13-4 shows the Watchdog Timer in Timer Mode. In this mode, any changes to WDCON are written to the shadow register after one watchdog clock cycle. A watchdog underflow will set the WDTOF bit. If IEN0.6 is set, the watchdog underflow is enabled to cause an interrupt. WDTOF is cleared by writing a '0' to this bit in software. When an underflow occurs, the contents of WDL is reloaded into the down counter and the watchdog timer immediately begins to count down again.

A feed is necessary to cause WDL to be loaded into the down counter before an underflow occurs. Incorrect feeds are ignored in this mode.

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WATCHDOG TIMER

MOV WFEED1, #0A5H MOV WFEED2, #05AH

Watchdog

Oscillator

CLK

÷32

PRESCALER

control register

WDL (C1H)

8-Bit Down

Counter

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Interrupt

SHADOW

WDCON

PRE2 PRE1 PRE0 WDRUN WDTOF WDCLK

WDCON(A7H)

Figure 13-4: Watchdog Timer in Timer Mode (WDTE = 0)

Power down operation

The WDT oscillator will continue to run in power down, consuming approximately 50uA, as long as the WDT oscillator is selected as the clock source for the WDT. Selecting PCLK as the WDT source will result in the WDT oscillator going into power down with the rest of the device (see section "Watchdog Clock Source" on page 88 ). Power down mode will also prevent PCLK from running and therefore the watchdog is effectively disabled.

Periodic wakeup from Power down without an external oscillator

Without using an external oscillator source, the power consumption required in order to have a periodic wakeup is determined by the power consumption of the internal oscillator source used to produce the wakeup.The Real-time clock running from the internal RC oscillator can be used. The power consumption of this oscillator is approximately 300uA. Instead, if the WDT is used to generate interrupts the current is reduced to approximately 50uA. Whenever the WDT underflows, the device will wake up.

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ADDITIONAL FEATURES

14. ADDITIONAL FEATURES

The AUXR1 register contains several special purpose control bits that relate to several chip features. AUXR1 is described in Figure 14-1.

AUXR1

Address: A2h

Not bit addressable

Reset Source(s): Any reset

Reset Value: 000000x0B

BIT SYMBOL FUNCTION

AUXR1.7 CLKLP Clock Low Power Select. When set, reduces power consumption in the clock circuits. Can

AUXR1.6 EBRR UART Break Detect Reset Enable. If ‘1’, UART Break Detect will cause a chip reset and

AUXR1.5 ENT1 When set, the P0.7 pin is toggled whenever Timer1 overflows. The output frequency is

AUXR1.4 ENT0 When set the P1.2 pin is toggled whenever Timer0 overflows. The output frequency is

AUXR1.3 SRST Software Reset. When set by software, resets the P89LPC920/921/922 as if a hardware

AUXR1.2 0 This bit contains a hard-wired 0. Allows toggling of the DPS bit by incrementing AUXR1,

AUXR1.1 - Not used. Allowable to set to a “1” .

AUXR1.0 DPS Data Pointer Select. Chooses one of two Data Pointers.

76543210

CLKLP EBRR ENT1 ENT0 SRST 0 - DPS

be used when the clock frequency is 8 MHz or less. After reset this bit is cleared to support up to 12 MHz operation.

force the device into ISP mode.

therefore one half of the Timer1 overflow rate. Refer to the Timer/Counters section for details.

therefore one half of the Timer0 overflow rate. Refer to the Timer/Counters section for details.

reset occurred.

without interfering with other bits in the register.

Figure 14-1: AUXR1 register

Software reset

The SRST bit in AUXR1 gives software the opportunity to reset the processor completely, as if an external reset or watchdog reset had occurred. If a value is written to AUXR1 that contains a 1 at bit position 3, all SFRs will be initialized and execution will resume at program address 0000. Care should be taken when writing to AUXR1 to avoid accidental software resets.

Dual Data Pointers

The dual Data Pointers (DPTR) adds to the ways in which the processor can specify the address used with certain instructions. The DPS bit in the AUXR1 register selects one of the two Data Pointers. The DPTR that is not currently selected is not accessible to software unless the DPS bit is toggled.

Specific instructions affected by the Data Pointer selection are:

• INC DPTR Increments the Data Pointer by 1.

• JMP @A+DPTR Jump indirect relative to DPTR value.

• MOV DPTR, #data16 Load the Data Pointer with a 16-bit constant.

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ADDITIONAL FEATURES

• MOVCA, @A+DPTR Move code byte relative to DPTR to the accumulator.

• MOVX A, @DPTR Move data byte the accumulator to data memory relative to DPTR.

• MOVX @DPTR, A Move data byte from data memory relative to DPTR to the accumulator.

Also, any instruction that reads or manipulates the DPH and DPL registers (the upper and lower bytes of the current DPTR) will be affected by the setting of DPS. The MOVX instructions have limited application for the P89LPC920/921/922 since the part does not have an external data bus. However, they may be used to access Flash configuration information (see Flash Configuration section) or auxiliary data (XDATA) memory.

Bit 2 of AUXR1 is permanently wired as a logic 0. This is so that the DPS bit may be toggled (thereby switching Data Pointers) simply by incrementing the AUXR1 register, without the possibility of inadvertently altering other bits in the register.

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FLASH MEMORY

15. FLASH MEMORY

General description

The P89LPC920/921/922 Flash memory provides in-circuit electrical erasure and programming. The Flash can be read and written as bytes. The Sector and Page Erase functions can erase any Flash sector (1 KB) or page (64 bytes). The Chip Erase operation will erase the entire program memory. Five Flash programming methods are available. On-chip erase and write timing generation contribute to a user-friendly programming interface. The P89LPC920/921/922 Flash reliably stores memory contents even after 100,000 erase and program cycles. The cell is designed to optimize the erase and programming mechanisms. The

P89LPC920/921/922 uses V

Features

• Parallel programming with industry-standard commercial programmers

• In-Circuit serial Programming (ICP) with industry-standard commercial programmers.

• IAP-Lite allows individual and multiple bytes of code memory to be used for data storage and programmed under control of the end application.

• Internal fixed boot ROM, containing low-level In-Application Programming (IAP) routines that can be called from the end application (in addition to IAP-Lite).

• Default serial loader providing In-System Programming (ISP) via the serial port, located in upper end of user program memory.

• Boot vector allows user provided Flash loader code to reside anywhere in the Flash memory space, providing flexibility to the user.

• Programming and erase over the full operating voltage range

• Read/Programming/Erase using ISP/IAP/IAP-Lite

• Any flash program operation in 2 ms (4ms for erase/program)

• Programmable security for the code in the Flash for each sector.

• > 100,000 typical erase/program cycles for each byte.

• 10-year minimum data retention.

as the supply voltage to perform the Program/Erase algorithms.

Flash programming and erase

The P89LPC920/921/922 program memory consists 1 KB sectors. Each sector can be further divided into 64-byte pages. In addition to sector erase and page erase, a 64-byte page register is included which allows from 1 to 64 bytes of a given page to be programmed at the same time, substantially reducing overall programming time. Five mthods of programming this device are available.

• Parallel programming with industry-standard commercial programmers.

• In-Circuit serial Programming (ICP) with industry-standard commercial programmers.

• IAP-Lite allows individual and multiple bytes of code memory to be used for data storage and programmed under control of the end application.

• Internal fixed boot ROM, containing low-level In-Application Programming (IAP) routines athat can be called from the end application (in addition to IAP-Lite).

• A factory-provided default serial loader, located in upper end of user program memory, providing In-System Programming

(ISP) via the serial port.

Using Flash as data storage: IAP-Lite

The Flash code memory array of this device supports IAP-Lite in addition to standard IAP functions. Any byte in a non-secured sector of the code memory array may be read using the MOVC instruction and thus is suitable for use as non-volatile data storage. IAP-Lite provides an erase-program function that makes it easy for one or more bytes within a page to be erased and pro-

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grammed in a single operation without the need to erase or program any other bytes in the page. IAP-Lite is performed in the application under the control of the microcontroller’s firmware using four SFRs and an internal 64-byte "page register" to facilitate erasing and programing within unsecured sectors. These SFRs are:

• FMCON (Flash Control Register). When read, this is the status register. When written, this is a command register. Note that the status bits are cleared to ’0’s when the command is written.

• FMDATA (Flash Data Register). Accepts data to be loaded into the page register.

• FMADRL, FMADRH (Flash memory address low, Flash memory address high). Used to specify the byte address within the page register or specify the page within user code memory.

The page register consists of 64 bytes and an update flag for each byte. When a LOAD command is issued to FMCON the page register contents and all of the update flags will be cleared. When FMDATA is written, the value written to FMDATA will be stored in the page register at the location specified by the lower 6 bits of FMADRL. In addition, the update flag for that location will be set. FMADRL will auto-increment to the next location. Auto-increment after writing to the last byte in the page register will "wrap -around" to the first byte in the page register, but will not affect FMADRL[7:6].. Bytes loaded into the page register do not have to be continous. Any byte location can be loaded into the page register by changing the contents of FMADRL prior to writing to FMDATA. However, each location in the page register can only be written once following each LOAD command. Attempts to write to a page register location more than once should be avoided.

FMADRH and FMADRL[7:6] are used to select a page of code memory for the erase-program function. When the erase-program command is written to FMCON, the locations within the code memory page that correspond to updated locations in the page register, will have their contents erased and programmed with the contents of their corresponding locations in the page register.Only the bytes that were loaded into the page register will be erased and programmed in the user code array. Other bytes within the user code memory will not be affected.

Writing the erase-program command (68H) to FMCON will start the erase-program process and place the CPU in a programidle state.The CPU will remain in this idle state until the erase-program cycle is either completed or terminated by an interrupt. When the program-idle state is exited FMCON will contain status information for the cycle.

If an interrupt occurs during an erase/programming cycle, the erase/programming cycle will be aborted and the OI flag (Operation Interrupted) in FMCON will be set. If the application permits interrupts during erasing-programming the user code should check the OI flag (FMCON.0) after each erase-programming operation to see if the operation was aborted. If the operation was aborted, the user’s code will need to repeat the process starting with loading the page register.

The erase-program cycle takes 4ms (2ms for erase, 2ms for programming) to complete, regardless of the number of bytes that were loaded into the page register.

Erasing-programming of a single byte (or multiple bytes) in code memory is accomplished using the following steps:

• Write the LOAD command (00H) to FMCON. The LOAD command will clear all locations in the page register and their corresponding update flags.

• Write the address within the page register to FMADRL. Since the loading the page register uses FMADRL[5:0], and since the erase-program command uses FMADRH and FMADRL[7:6], the user can write the byte location within the page register (FMADRL[5:0]) and the code memory page address (FMADRH and FMADRL[7:6]) at this time.

• Write the data to be programmed to FMDATA. This will increment FMADRL pointing to the next byte in the page register.

• Write the address of the next byte to be programmed to FMADRL, if desired. (Not needed for contiguous bytes since FMADRL is auto-incremented). All bytes to be programmed must be within the same page.

• Write the data for the next byte to be programmed to FMDATA.

• Repeat writing of FMADRL and/or FMDATA until all desired bytes have been loaded into the page register.

• Write the page address in user code memory to FMADRH and FMADRL[7:6], if not previously included when writing the page register address to FMADRL[5:0].

• Write the erase-program command (68H) to FMCON,starting the erase-program cycle.

• Read FMCON to check status. If aborted, repeat starting with the LOAD command.

An assembly language routine to load the page register and perform an erase/program operation is shown in Figure 15-2. A

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FLASH MEMORY

similar C-language routine is shown in Figure 15-3.

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FMCON

Address: E4h

Not bit addressable

Reset Source(s): Any reset

Reset Value:

BIT SYMBOL FUNCTION

FMCON.7-4 - Reserved.

FMCON.3 HVA High voltage abort. Set if either an interrupt or a brown-out is detected during a program

FMCON.2 HVE High voltage error. Set when an error occurs in the high voltage generator.

FMCON.1 SV Security violation. Set when an attempt is made to program, erase, or CRC a secured

FMCON.0 OI Operation interrupted. Set when cycle aborted due to an interrupt or reset.

76543210

- - - - HVA HVE SV OI

or erase cycle. Also set if the brown-out detector is disabled at the start of a program or erase cycle.

sector or page.

Figure 15-1: Flash Memory Control Registe

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FLASH MEMORY

;* Inputs: * ;* R3 = number of bytes to program (byte) * ;* R4 = page address MSB(byte) * ;* R5 = page address LSB(byte) * ;* R7 = pointer to data buffer in RAM(byte) * ;* Outputs: * ;* R7 = status (byte) * ;* C = clear on no error, set on error *

LOAD EQU 00H EP EQU 68H

PGM_USER: MOV FMCON,#LOAD ;load command, clears page register MOV FMADRH,R4 ;get high address MOV FMADRL,R5 ;get low address MOV A,R7 ; MOV R0,A ;get pointer into R0 LOAD_PAGE: MOV FMDAT,@R0 ;write data to page register INC R0 ;point to next byte DJNZ R3,LOAD_PAGE ;do until count is zero MOV FMCON,#EP ;else erase & program the page

MOV R7,FMCON ;copy status for return MOV A,R7 ;read status ANL A,#0FH ;save only four lower bits JNZ BAD ; CLR C ;clear error flag if good RET ;and return BAD: SETB C ;set error flag RET ;and return

Figure 15-2: Assembly language routine to erase/program all or part of a page

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#include <REG931.H>

unsigned char idata dbytes[64]; // data buffer unsigned char Fm_stat; // status result

bit PGM_USER (unsigned char, unsigned char); bit prog_fail;

void main ()

{ prog_fail=PGM_USER(0x1F,0xC0); }

bit PGM_USER (unsigned char page_hi, unsigned char page_lo) { #define LOAD 0x00 // clear page register, enable loading #define EP 0x68 // erase & program page unsigned char i; // loop count

FMCON = LOAD; //load command, clears page reg FMADRH = page_hi; // FMADRL = page_lo; //write my page address to addr regs

for (i=0;i<64;i=i+1) { FMDATA = dbytes[i]; } FMCON = EP; //erase & prog page command Fm_stat = FMCON; //read the result status if ((Fm_stat & 0x0F)!=0) prog_fail=1; else prog_fail=0; return(prog_fail); }

Figure 15-3: C-language routine to erase/program all or part of a page

In-Circuit Programming (ICP)

In-Circuit Programming is a method intended to allow commercial programmers to program and erase these devices without removing the microcontroller from the system. The In-Circuit Programming facility consists of a series of internal hardware resources to facilitate remote programming of the P89LPC920/921/922 through a two-wire serial interface. Philips has made incircuit programming in an embedded application possible with a minimum of additional expense in components and circuit board area. The ICP function uses five pins (Vdd, Vss, P0.5, P0.4, and RST interface your application to an external programmer in order to use this feature.

). Only a small connector needs to be available to

ISP and IAP capabilities of the P89LPC920/921/922

An In-Application Programming (IAP) interface is provided to allow the end user’s application to erase and reprogram the user code memory. In addition, erasing and reprogramming of user-programmable bytes including UCFG1, the Boot Status Bit, and the Boot Vector is supported. As shipped from the factory, the upper 512 bytes of user code space contains a serial In-System Programming (ISP) loader allowing for the device to be programmed in circuit through the serial port. This ISP boot loader will, in turn, call low-level routines through the same common entry point that can be used by the end-user application.

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FLASH MEMORY

Boot ROM

When the microcontroller contains a a 256 byte Boot ROM that is separate from the user’s Flash program memory. This Boot ROM contains routines which handle all of the low level details needed to erase and program the user Flash memory . A user program simply calls a common entry point in the Boot ROM with appropriate parameters to accomplish the desired operation. Boot ROM operations include operations such as erase sector, erase page, program page, CRC, program security bit, etc. The Boot ROM occupies the program memory space at the top of the address space from FF00 to FFFF hex, thereby not conflicting with the user program memory space.This function is in addition to the IAP-Lite feature.

Power-On reset code execution

The P89LPC920/921/922 contains two special Flash elements: the BOOT VECTOR and the Boot Status Bit. Following reset, the P89LPC920/921/922 examines the contents of the Boot Status Bit. If the Boot Status Bit is set to zero, power-up execution starts at location 0000H, which is the normal start address of the user’s application code. When the Boot Status Bit is set to a va one, the contents of the Boot Vector is used as the high byte of the execution address and the low byte is set to 00H.

The factory default settings for these devcies are show in Table 15-1, below.The factory pre-programmed boot loader can be erased by the user. Users who wish to use this loader should take cautions to avoid erasing the last 1KB sector on the device. Instead, the page erase function can be used to erase the eight 64-byte pages located in this sector. A custom boot loader can be written with the Boot Vector set to the custom boot loader, if desired.

Table 15-1: Boot Loader Address and Default Boot Vector

PRODUCT

P89LPC922 8K x 8 1FFF 15H DDH 0CH

P89LPC921 4K x 8 0FFF 15H DDH 0BH

P89LPC920 2K x 8 07FF 15H DDH 1AH 1Kx8 64x8 0600H-07FFH 07H

FLASH

SIZE

END

ADDRESS

SIGNATURE BYTES

MFG ID1 ID2

or 15H DDH 05H

SECTOR

SIZE

1Kx8 64x8 1E00H-1FFFH 1FH

1Kx8 64x8 0E00H-0FFFH 0FH

PAGE

SIZE

PRE-PROGRAMMED

SERIAL LOADER

DEFAULT

BOOT

VECTOR

Hardware activation of the Boot Loader

The boot loader can also be executed by forcing the device into ISP mode during a power-on sequence (see Figure 15-4).This is accomplished by powering up the device with the reset pin initially held low and holding the pin low for a fixed time after VDD rises to its normal operating value. This is followed by three, and only three, properly timed low-going pulses. Fewer or more than three pulses will result in the device not entering ISP mode. Timing specifications may be found in the datasheet for this device.

This has the same effect as having a non-zero status bit. This allows an application to be built that will normally execute the user code but can be manually forced into ISP operation. If the factory default setting for the Boot Vector is changed, it will no longer point to the factory pre-programmed ISP boot loader code. If this happens, the only way it is possible to change the contents of the Boot Vector is through the parallel or ICP programming method, provided that the end user application does not contain a customized loader that provides for erasing and reprogramming of the Boot Vector and Boot Status Bit. After programming the Flash, the status byte should be programmed to zero in order to allow execution of the user’s application code beginning at address 0000H.

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Philips Semiconductors

User’s Manual - Preliminary -

P89LPC920/921/922

FLASH MEMORY

VDD

RST

In-System Programming (ISP)

In-System Programming is performed without removing the microcontroller from the system. The In-System Programming facility consists of a series of internal hardware resources coupled with internal firmware to facilitate remote programming of the

P89LPC920/921/922 through the serial port. This firmware is provided by Philips and embedded within each P89LPC920/921/ 922 device. The Philips In-System Programming facility has made in-circuit programming in an embedded application possible

with a minimum of additional expense in components and circuit board area. The ISP function uses five pins (Vdd, Vss, TxD, RxD, and RST). Only a small connector needs to be available to interface your application to an external circuit in order to use this feature.

Figure 15-4: Forcing ISP Mode

Using the In-System Programming

The ISP feature allows for a wide range of baud rates to be used in your application, independent of the oscillator frequency. It is also adaptable to a wide range of oscillator frequencies. This is accomplished by measuring the bit-time of a single bit in a received character. This information is then used to program the baud rate in terms of timer counts based on the oscillator frequency. The ISP feature requires that an initial character (an uppercase U) be sent to the P89LPC920/921/922 to establish the baud rate. The ISP firmware provides auto-echo of received characters. Once baud rate initialization has been performed, the ISP firmware will only accept Intel Hex-type records. Intel Hex records consist of ASCII characters used to represent hexadecimal values and are summarized below:

:NNAAAARRDD..DDCC<crlf>

In the Intel Hex record, the “NN” represents the number of data bytes in the record. The P89LPC920/921/922 will accept up to 64 (40H) data bytes. The “AAAA” string represents the address of the first byte in the record. If there are zero bytes in the record, this field is often set to 0000. The “RR” string indicates the record type. A record type of “00” is a data record. A record type of “01” indicates the end-of-file mark. In this application, additional record types will be added to indicate either commands or data for the ISP facility. The maximum number of data bytes in a record is limited to 64 (decimal). ISP commands are summarized in Table 15-2 . As a record is received by the P89LPC920/921/922, the information in the record is stored internally and a checksum calculation is performed. The operation indicated by the record type is not performed until the entire record has been received. Should an error occur in the checksum, the P89LPC920/921/922 will send an “X” out the serial port indicating a checksum error. If the checksum calculation is found to match the checksum in the record, then the command will be executed. In most cases, successful reception of the record will be indicated by transmitting a “.” character out the serial port

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Philips Semiconductors

FLASH MEMORY

Table 15-2: In-System Programming (ISP) hex record formats

Record type Command/data function

Program User Code Memory Page

:nnaaaa00dd..ddcc

Where:

nn = number of bytes to program

aaaa = page address

dd..dd = data bytes

cc = checksum

Example:

:100000000102030405006070809cc

Read Version Id

:00xxxx01cc

Where:

xxxx = required field but value is a “don’t care”

cc = checksum

Example:

:00000001cc

User’s Manual - Preliminary -

P89LPC920/921/922

2003 Nov 6 100

Philips P89LPC920, P89LPC921, P89LPC922 Technical data

Specifications and Main Features

Frequently Asked Questions

User Manual

1. General Description

Pin configuration

20-Pin TSSOP, DIP Package

Logic symbol

Pin Descriptions

Special Function Registers

Memory organization

DATA RAM ARRANGEMENT

CLOCKS

2. CLOCKS

Enhanced CPU

Clock definitions

Oscillator clock (OSCCLK)

Low speed oscillator option

Medium speed oscillator option

High speed oscillator option

Clock output

On-chip RC oscillator option

Watchdog oscillator option

External clock input option

Oscillator Clock (OSCCLK) wakeup delay

CPU Clock (CCLK) modification: DIVM register

Low power select

3. INTERRUPTS

Interrupt priority structure

External Interrupt pin glitch suppression

4. I/O PORTS

Port configurations

Quasi-bidirectional output configuration

Open drain output configuration

Input-only configuration

Push-pull output configuration

Port 0 analog functions

Additional port features

5. POWER MONITORING FUNCTIONS

Brownout Detection

Power-on Detection

Power reduction modes

6. RESET

Reset vector

7. TIMERS 0 AND 1

Mode 0

Mode 1

Mode 2

Mode 3

Mode 6

Timer overflow toggle output

8. REAL-TIME CLOCK/SYSTEM TIMER

Real-time Clock source

Changing RTCS1-0

Real-time Clock interrupt/wake up

Reset sources affecting the Real-time Clock

9. UART

Mode 0

Mode 1

Mode 2

Mode 3

SFR space

Baud Rate Generator and selection

Updating the BRGR1 and BRGR0 SFRs

Framing Error

Break Detect

More about UART Mode 0

More about UART Mode 1

More about UART Modes 2 and 3

Framing Error and RI in Modes 2 and 3 with SM2 = 1

Break Detect

Double buffering

Double buffering in different modes

Transmit interrupts with double buffering enabled (Modes 1, 2 and 3)

The 9th bit (bit 8) in double buffering (Modes 1, 2 and 3)

Multiprocessor communications

Automatic address recognition

10. I2C INTERFACE

I2C Data register

I2C Slave Address register