ATMEL AT89C5131A-L User Manual

BDTIC www.bdtic.com/ATMEL

Features

• 80C52X2 Core (6 Clocks per Instruction)

– Maximum Core Frequency 48 MHz in X1 Mode, 24 MHz in X2 Mode – Dual Data Pointer – Full-duplex Enhanced UART (EUART) – Three 16-bit Timer/Counters: T0, T1 and T2 – 256 Bytes of Scratchpad RAM

• 16/32-Kbyte On-chip Flash EEPROM In-System Programming through USB

– Byte and Page (128 bytes) Erase and Write – 100k Write Cycles

• 3-KbyteFlash EEPROM for Bootloader

– Byte and Page (128 bytes) Erase and Write – 100k Write Cycles

• 1-Kbyte EEPROM Data (

– Byte and Page (128 bytes) Erase and Write – 100k Write Cycles

• On-chip Expanded RAM (ERAM): 1024 Bytes

• Integrated Power Monitor (POR/PFD) to Supervise Internal Power Supply

• USB 1.1 and 2.0 Full Speed Compliant Module with Interrupt on Transfer Completion

– Endpoint 0 for Control Transfers: 32-byte FIFO – 6 Programmable Endpoints with In or Out Directions and with Bulk, Interrupt or

Isochronous Transfers

• Endpoint 1, 2, 3: 32-byte FIFO

• Endpoint 4, 5: 2 x 64-byte FIFO with Double Buffering (Ping-pong Mode)

• Endpoint 6: 2 x 512-byte FIFO with Double Buffering (Ping-pong Mode) – Suspend/Resume Interrupts – Power-on Reset and USB Bus Reset – 48 MHz DPLL for Full-speed Bus Operation – USB Bus Disconnection on Microcontroller Request

• 5 Channels Programmable Counter Array (PCA) with 16-bit Counter, High-speed

Output, Compare/Capture, PWM and Watchdog Timer Capabilities

• Programmable Hardware Watchdog Timer (One-time Enabled with Reset-out): 50 ms to

6s at 4 MHz

• Keyboard Interrupt Interface on Port P1 (8 Bits)

• TWI (Two Wire Interface) 400Kbit/s

• SPI Interface (Master/Slave Mode)

• 34 I/O Pins

• 4 Direct-drive LED Outputs with Programmable Current Sources: 2-6-10 mA Typical

• 4-level Priority Interrupt System (11 sources)

• Idle and Power-down Modes

• 0 to 32 MHz On-chip Oscillator with Analog PLL for 48 MHz Synthesis

• Industrial Temperature Range

• Low Voltage Range Supply: 2.7V to 3.6V (3.0V to 3.6V required for USB)

• Packages: SO28, PLCC52, VQFP64

8-bit Flash Microcontroller with Full Speed USB Device

AT89C5131A-L

Rev. 4338F–USB–08/07

AT89C5131A-L

Description

AT89C5131A-L is a high-performance Flash version of the 80C51 single-chip 8-bit microcontrollers with full speed USB functions.

AT89C5131A-L features a full-speed USB module compatible with the USB specifications Version 1.1 and 2.0. This module integrates the USB transceivers with a 3.3V voltage regulator and the Serial Interface Engine (SIE) with Digital Phase Locked Loop and 48 MHz clock recovery. USB Event detection logic (Reset and Suspend/Resume) and FIFO buffers supporting the mandatory control Endpoint (EP0) and up to 6 versatile Endpoints (EP1/EP2/EP3/EP4/EP5/EP6) with minimum software overhead are also part of the USB module.

AT89C5131A-L retains the features of the Atmel 80C52 with extended Flash capacity (3 2 -Kbyt e), 256 b ytes of int ernal R AM, a 4-l evel int errup t syste m, two 16 -bit timer/counters (T0/ T1), a full duplex enhanced U ART (EUART) and an on-chip oscillator.

In addition, AT89C5131A-L has an on-chip expanded RAM of 1024 bytes (ERAM), a dual- data pointer, a 16-bit up/down Timer (T2), a Programmable Counter Array (PCA), up to 4 programmable LED current sources, a programmable hardware watchdog and a power-on reset.

AT89C5131A-L has two software-selectable modes of reduced activity for further reduction in power consumption. In the idle mode the CPU is frozen while the timers, the serial ports and the interrupt system are still operating. In the power-down mode the RAM is saved, the peripheral clock is frozen, but the device has full wake-up capability through USB events or external interrupts.

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Block Diagram

Timer 0

INT

RAM

256x8

RxD

TxD

PSEN

ALE

XTAL2

XTAL1

EUART

CPU

Timer 1

INT1

Ctrl

INT0

(2)

C51

CORE

(2) (2) (2) (2)

Port 0P0Port 1

Port 2

Port 3

Parallel I/O Ports & Ext. Bus

ERAM

1Kx8

PCA

RST

Watch

Dog

CEX

ECI

VSS

VDD

(2)(2)

(1)(1)

Timer2

T2EX

(1)

Port 4

32Kx8 Flash

BRG

USB

D -

D +

VREF

Regu-

Key

Board

KIN

lator

AVSS

EEPROM

4Kx8

SPI

MISO

MOSI

SCK

(1) (1) (1)

(1)

AVDD

TWI

SCL

SDA

AT89C5131A-L

Notes: 1. Alternate function of Port 1

2. Alternate function of Port 3

3. Alternate function of Port 4

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AT89C5131A-L

Pinout Description

21 22 26252423 292827 30 31

5 4 3 2 1 6

52 51 50 49 48

40 39

PLCC52

32 33

P1.1/T2EX/KIN1/SS

P1.0/T2/KIN0

P0.6/AD6

ALE

P0.7/AD7

PSEN

P1.7/CEX4/KIN7/MOSI

P1.3/CEX0/KIN3

P1.5/CEX2/KIN5/MISO

P1.6/CEX3/KIN6/SCK

PLLF

P3.0/RxD

AVSS

P2.6/A14

XTAL1

P2.5/A13

P0.3/AD3

P0.5/AD5

P0.4/AD4

VREF

P0.2/AD2

P0.0/AD0

P0.1/AD1

AVDD

P3.2/INT0

P3.6/WR/LED2

XTAL2

RST

P3.1/TxD

P3.3/INT1/LED0

P3.7/RD/LED3

D-

P2.0/A8

P2.1/A9

P2.2/A10

P2.3/A11

VSS

P2.4/A12

P4.1/SDA

D+

P4.0/SCL

P1.2/ECI/KIN2

P1.4/CEX1/KIN4

P3.4/T0

P3.5/T1/LED1

VDD

P2.7/A15

Pinout

Figure 1. AT89C5131A-L 52-pin PLCC Pinout

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Figure 2. AT89C5131A-L 64-pin VQFP Pinout

17 18 22212019 252423 26 27

62 61 60 59 58 63

57 56 55 54 53

1 2

48 47

41 40

VQFP64

12 13

51 50

15 16

31 32

P1.1/T2EX/KIN1/SS

ALE

PSEN

P1.7/CEX4/KIN7/MOSI

P1.3/CEX0/KIN3

P1.5/CEX2/KIN5/MISO

P1.6/CEX3/KIN6/SCK

P2.7/A15

P2.6/A14

P4.1/SDA

P1.2/ECI/KIN2

P1.4/CEX1/KIN4

P1.0/T2/KIN0

PLLF

XTAL2

RST

P3.7/RD/LED3

P2.0/A8

P2.1/A9

P2.2/A10

P2.3/A11

P2.4/A12

P3.0/RxD

VREF

P0.0/AD0

AVSS

P3.2/INT0

P3.6/WR/LED2

P3.1/TxD

P3.3/INT1/LED0

VSS

P3.4/T0

P3.5/T1/LED1

P0.6/AD6 P0.7/AD7

P2.5/A13

P0.3/AD3

P0.5/AD5

P0.4/AD4

P0.2/AD2

P0.1/AD1

D-

D+

P4.0/SCL

XTAL1

AVDD

VDD

P1.1/T2EX/KIN1/SS

PLLF

P3.0/RxD

P1.0/T2/KIN0

AVSS

VDD

XTAL1

XTAL2

P3.2/INT0

P3.5/T1/LED1

P3.6/WR/LED2

P3.7/RD/LED3

D-

P1.4/CEX1/KIN4

VSS

D+

P1.2/ECI/KIN2

P1.3/CEX0/KIN3

P1.5/CEX2/KIN5/MISO

RST

P1.6/CEX3/KIN6/SCK

P1.7/CEX4/KIN7/MOSI

P4.0/SCL

VREF P3.1/TxD

P3.4/T0

3 4

7 8

27 26

24 23

19 18

SO28

P4.1/SDA

P3.3/INT1/LED0

AT89C5131A-L

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Figure 3. AT89C5131A-L 28-pin SO Pinout

AT89C5131A-L

Signals

All the AT89C5131A-L signals are detailed by functionality on Table 1 through Table 12.

Table 1. Keypad Interface Signal Description

Signal Name Type Description

KIN[7:0) I

Keypad Input Lines

Holding one of these pins high or low for 24 oscillator periods triggers a keypad interrupt if enabled. Held line is reported in the KBCON register.

Table 2. Programmable Counter Array Signal Description

Signal

Name Type Description

ECI I External Clock Input P1.2

Capture External Input

CEX[4:0] I/O

Compare External Output

Table 3. Serial I/O Signal Description

Signal Name Type Description

RxD I

Serial Input

The serial input for Extended UART.

Alternate Function

P1[7:0]

Alternate Function

P1.3

P1.4

P1.5

P1.6

P1.7

Alternate Function

P3.0

TxD O

Serial Output

The serial output for Extended UART.

Table 4. Timer 0, Timer 1 and Timer 2 Signal Description

Signal Name Type Description

Timer 0 Gate Input

INT0 serves as external run control for timer 0, when selected by GATE0 bit in TCON register.

INT0 I

INT1 I

External Interrupt 0

INT0 input set IE0 in the TCON register. If bit IT0 in this register is set, bits IE0 are set by a falling edge on INT0. If bit IT0 is cleared, bits IE0 is set by a low level on INT0.

Timer 1 Gate Input

INT1 serves as external run control for Timer 1, when selected by GATE1 bit in TCON register.

External Interrupt 1

INT1 input set IE1 in the TCON register. If bit IT1 in this register is set, bits IE1 are set by a falling edge on INT1. If bit IT1 is cleared, bits IE1 is set by a low level on INT1.

P3.1

Alternate Function

P3.2

P3.3

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AT89C5131A-L

Table 4. Timer 0, Timer 1 and Timer 2 Signal Description (Continued)

Signal Name Type Description

Alternate Function

T0 I

T1 I

T2EX I Timer/Counter 2 Reload/Capture/Direction Control Input P1.1

Timer Counter 0 External Clock Input

When Timer 0 operates as a counter, a falling edge on the T0 pin increments the count.

Timer/Counter 1 External Clock Input

When Timer 1 operates as a counter, a falling edge on the T1 pin increments the count.

IOTimer/Counter 2 External Clock Input

Timer/Counter 2 Clock Output

Table 5. LED Signal Description

Signal

Name Type Description

Direct Drive LED Output

LED[3:0] O

These pins can be directly connected to the Cathode of standard LEDs without external current limiting resistors. The typical current of each output can be programmed by software to 2, 6 or 10 mA. Several outputs can be connected together to get higher drive capabilities.

Table 6. TWI Signal Description

Signal

Name Type Description

P3.4

P3.5

P1.0

Alternate Function

P3.3

P3.5

P3.6

P3.7

Alternate Function

SCL I/O

SDA I/O

SCL: TWI Serial Clock

SCL output the serial clock to slave peripherals. SCL input the serial clock from master.

SDA: TWI Serial Data

SCL is the bidirectional TWI data line.

Table 7. SPI Signal Description

Signal Name Type Description

SS I/O SS: SPI Slave Select P1.1

MISO: SPI Master Input Slave Output line

MISO I/O

SCK I/O

MOSI

When SPI is in master mode, MISO receives data from the slave peripheral. When SPI is in slave mode, MISO outputs data to the master controller.

SCK: SPI Serial Clock

SCK outputs clock to the slave peripheral or receive clock from the master

MOSI: SPI Master Output Slave Input line

I/O

When SPI is in master mode, MOSI outputs data to the slave peripheral. When SPI is in slave mode, MOSI receives data from the master controller

P4.0

P4.1

Alternate Function

P1.5

P1.6

P1.7

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AT89C5131A-L

Table 8. Ports Signal Description

Signal

Name Type Description Alternate Function

Port 0

P0 is an 8-bit open-drain bidirectional I/O port. Port 0

P0[7:0] I/O

P1[7:0] I/O

pins that have 1s written to them float and can be used as high impedance inputs. To avoid any parasitic current consumption, Floating P0 inputs must be pulled to V VSS.

Port 1

P1 is an 8-bit bidirectional I/O port with internal pull-ups.

AD[7:0]

KIN[7:0]

T2EX

ECI

CEX[4:0]

P2[7:0] I/O

P3[7:0] I/O

P4[1:0] I/O

Port 2

P2 is an 8-bit bidirectional I/O port with internal pull-ups.

Port 3

P3 is an 8-bit bidirectional I/O port with internal pull-ups.

Port 4

P4 is an 2-bit open port.

Table 9. Clock Signal Description

Signal Name Type Description

XTAL1 I

XTAL2 O

Input to the on-chip inverting oscillator amplifier

To use the internal oscillator, a crystal/resonator circuit is connected to this pin. If an external oscillator is used, its output is connected to this pin.

Output of the on-chip inverting oscillator amplifier

To use the internal oscillator, a crystal/resonator circuit is connected to this pin. If an external oscillator is used, leave XTAL2 unconnected.

A[15:8]

LED[3:0]

RxD

TxD

INT0 INT1

T0 T1

SCL

SDA

Alternate Function

PLLF I

PLL Low Pass Filter input

Receives the RC network of the PLL low pass filter (See Figure 4 on page 11 ).

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Table 10. USB Signal Description

AT89C5131A-L

Signal Name Type Description

D+ I/O

D- I/O

VREF O

USB Data + signal

Set to high level under reset.

USB Data - signal

Set to low level under reset.

USB Reference Voltage

Connect this pin to D+ using a 1.5 kΩ resistor to use the Detach function.

Table 11. System Signal Description

Signal Name Type Description

AD[7:0] I/O

A[15:8] I/O

RD I/O

WR I/O

Multiplexed Address/Data LSB for external access

Data LSB for Slave port access (used for 8-bit and 16-bit modes)

Address Bus MSB for external access

Data MSB for Slave port access (used for 16-bit mode only)

Read Signal

Read signal asserted during external data memory read operation.

Control input for slave port read access cycles.

Write Signal

Write signal asserted during external data memory write operation.

Control input for slave write access cycles.

Alternate Function

P0[7:0]

P2[7:0]

P3.7

P3.6

RST I/O

ALE O

PSEN O

EA I

Reset

Holding this pin low for 64 oscillator periods while the oscillator is running resets the device. The Port pins are driven to their reset conditions when a voltage lower than VIL is applied, whether or not the oscillator is running. This pin has an internal pull-up resistor which allows the device to be reset by connecting a capacitor between this pin and VSS. Asserting RST when the chip is in Idle mode or Power-down mode returns the chip to normal operation. This pin is set to 0 for at least 12 oscillator periods when an internal reset occurs (hardware watchdog or Power monitor).

Address Latch Enable Output

The falling edge of ALE strobes the address into external latch. This signal is active only when reading or writing external memory using MOVX instructions.

Program Strobe Enable / Hardware conditions Input for ISP

Used as input under reset to detect external hardware conditions of ISP mode

External Access Enable

This pin must be held low to force the device to fetch code from external program memory starting at address 0000h. It is latched during reset and cannot be dynamically changed during operation.

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AT89C5131A-L

Table 12. Power Signal Description

Signal Name Type Description

Alternate Function

AVSS GND

AVDD PWR

VSS GND

VDD PWR

VREF O

Alternate Ground

AVSS is used to supply the on-chip PLL and the USB PAD.

Alternate Supply Voltage

AVDD is used to supply the on-chip PLL and the USB PAD.

Digital Ground

VSS is used to supply the buffer ring and the digital core.

Digital Supply Voltage

VDD is used to supply the buffer ring on all versions of the device.

It is also used to power the on-chip voltage regulator of the Standard versions or the digital core of the Low Power versions.

USB pull-up Controlled Output

VREF is used to control the USB D+ 1.5 kΩ pull up.

The Vref output is in high impedance when the bit DETACH is set in the USBCON register.

4338F–USB–08/07

Typical Application

VSS

XTAL1

XTAL2

22pF

VSS

PLLF

100R

10nF

2.2nF

VSS

AVSS

VSS

D-

D+

27R

VRef

1.5K

USB

D+

D-

VBUS

GND

VSS

VDD

AVDD

VDD

4.7µF

VSS

100nF

VSS

100nF

VSS

AT89C5131A-L

Recommended External components

All the external components described in the figure below must be implemented as close as possible from the microcontroller package.

The following figure represents the typical wiring schematic.

Figure 4. Typical Application

AT89C5131A-L

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AT89C5131A-L

PCB Recommandations

D+

VRef

D-

USB Connector

Wires must be routed in Parallel and

Components must be

If possible, isolate D+ and D- signals from other signals with ground wires

must be as short as possible

close to the microcontroller

PLLFAVss

Components must be

Isolate filter components

with a ground wire

microcontroller

close to the

Figure 5. USB Pads

Figure 6. USB PLL

4338F–USB–08/07

Clock Controller

PCON.1

IDL

PCON.0

Peripheral

CPU Core

CKCON.0

Clock

EXT48

PLLCON.2

PLL

USB Clock

AT89C5131A-L

Introduction

Figure 7. Oscillator Block Diagram

The AT89C5131A-L clock controller is based on an on-chip oscillator feeding an on-chip Phase Lock Loop (PLL). All the internal clocks to the peripherals and CPU core are generated by this controller.

The AT89C5131A-L X1 and X2 pins are the input and the output of a single-stage onchip inverter (see Figure 7) that can be configured with off-chip components as a Pierce oscillator (see Figure 8). Value of capacitors and crystal characteristics are detailed in the section “DC Characteristics”.

The X1 pin can also be used as input for an external 48 MHz clock.

The clock controller outputs three different clocks as shown in Figure 7:

• a clock for the CPU core

• a clock for the peripherals which is used to generate the Timers, PCA, WD, and Port sampling clocks

• a clock for the USB controller

These clocks are enabled or disabled depending on the power reduction mode as detailed in Section “Power Management”, page 152.

Oscillator

4338F–USB–08/07

Two clock sources are available for CPU:

• Crystal oscillator on X1 and X2 pins: Up to 32 MHz

• External 48 MHz clock on X1 pin

In order to optimize the power consumption, the oscillator inverter is inactive when the PLL output is not selected for the USB device.

AT89C5131A-L

Figure 8. Crystal Connection

VSS

PLLEN

PLLCON.1

N3:0

N divider

R divider

VCO USB Clock

US Bclk

OSCclk R 1+( )×

N 1+

-----------------------------------------------=

OSC

CLOCK

PFLD

PLOCK

PLLCON.0

PLLF

CHP

Vref

Down

R3:0

USB

CLOCK

USB Clock Symbol

VSS

PLLF

VSS

PLL

PLL Description The AT89C5131A-L PLL is used to generate internal high frequency clock (the USB

Clock) synchronized with an external low-frequency (the Peripheral Clock). The PLL clock is used to generate the USB interface clock. Figure 9 shows the internal structure of the PLL.

The PFLD block is the Phase Frequency Comparator and Lock Detector. This block makes the comparison between the reference clock coming from the N divider and the reverse clock coming from the R divider and generates some pulses on the Up or Down signal depending on the edge position of the reverse clock. The PLLEN bit in PLLCON register is used to enable the clock generation. When the PLL is locked, the bit PLOCK in PLLCON register (see Figure 9) is set.

The CHP block is the Charge Pump that generates the voltage reference for the VCO by injecting or extracting charges from the external filter connected on PLLF pin (see Figure 10 ) . Value o f the fil ter c o m p onents a r e d etailed i n t h e Section “ D C Characteristics”.

Figure 9. PLL Block Diagram and Symbol

The VCO block is the Voltage Controlled Oscillator controlled by the voltage V duced by the charge pump. It generates a square wave signal: the PLL clock.

Figure 10. PLL Filter Connection

The typical values are: R = 100 Ω, C1 = 10 nf, C2 = 2.2 nF.

REF

pro-

4338F–USB–08/07

AT89C5131A-L

PLL

Programming

Configure Dividers

N3:0 = xxxxb R3:0 = xxxxb

Enable PLL

PLLEN = 1

PLL Locked?

LOCK = 1?

PLL Programming The PLL is programmed using the flow shown in Figure 11. As soon as clock generation

is enabled user must wait until the lock indicator is set to ensure the clock output is stable.

Figure 11. PLL Programming Flow

Divider Values To generate a 48 MHz clock using the PLL, the divider values have to be configured fol-

lowing the oscillator frequency. The typical divider values are shown in Table 13.

Table 13. Typical Divider Values

Oscillator Frequency R+1 N+1 PLLDIV

3 MHz 16 1 F0h

6 MHz 8 1 70h

8 MHz 6 1 50h

12 MHz 4 1 30h

16 MHz 3 1 20h

18 MHz 8 3 72h

20 MHz 12 5 B4h

24 MHz 2 1 10h

32 MHz 3 2 21h

40 MHz 12 10 B9h

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AT89C5131A-L

Registers

Table 14. CKCON0 (S:8Fh)

Clock Control Register 0

7 6 5 4 3 2 1 0

TWIX2 WDX2 PCAX2 SIX2 T2X2 T1X2 T0X2 X2

Bit Number

7 TWIX2

6 WDX2

5 PCAX2

4 SIX2

3 T2X2

Bit

Mnemonic Description

TWI Clock This control bit is validated when the CPU clock X2 is set. When X2 is low, this bit has no effect.

Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle.

Watchdog Clock This control bit is validated when the CPU clock X2 is set. When X2 is low, this bit has no effect.

Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle.

Programmable Counter Array Clock This control bit is validated when the CPU clock X2 is set. When X2 is low, this bit has no effect.

Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle.

Enhanced UART Clock (Mode 0 and 2) This control bit is validated when the CPU clock X2 is set. When X2 is low, this bit has no effect.

Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle.

Timer2 Clock This control bit is validated when the CPU clock X2 is set. When X2 is low, this bit has no effect.

Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle.

Timer1 Clock

2 T1X2

1 T0X2

0 X2

This control bit is validated when the CPU clock X2 is set. When X2 is low, this bit has no effect.

Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle.

Timer0 Clock This control bit is validated when the CPU clock X2 is set. When X2 is low, this bit has no effect.

Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle.

System Clock Control bit

Clear to select 12 clock periods per machine cycle (STD mode, F F

OSC

Set to select 6 clock periods per machine cycle (X2 mode, F

Reset Value = 0000 0000b

= F

CPU

2).

CPU = FPER = FOSC

PER =

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AT89C5131A-L

Table 15. CKCON1 (S:AFh)

Clock Control Register 1

7 6 5 4 3 2 1 0

- - - - - - - SPIX2

Bit Number

7-1 -

0 SPIX2

Bit

Mnemonic Description

Reserved

The value read from this bit is always 0. Do not set this bit.

SPI Clock This control bit is validated when the CPU clock X2 is set. When X2 is low, this bit has no effect.

Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle.

Reset Value = 0000 0000b

Table 16. PLLCON (S:A3h) PLL Control Register

7 6 5 4 3 2 1 0

- - - - - EXT48 PLLEN PLOCK

Bit Number

7-3 -

2 EXT48

Bit

Mnemonic Description

Reserved

The value read from this bit is always 0. Do not set this bit.

External 48 MHz Enable Bit

Set this bit to bypass the PLL and disable the crystal oscillator. Clear this bit to select the PLL output as USB clock and to enable the crystal oscillator.

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PLL Enable Bit

1 PLLEN

0 PLOCK

Set to enable the PLL. Clear to disable the PLL.

PLL Lock Indicator

Set by hardware when PLL is locked. Clear by hardware when PLL is unlocked.

Reset Value = 0000 0000b Table 17. PLLDIV (S:A4h) PLL Divider Register

7 6 5 4 3 2 1 0

R3 R2 R1 R0 N3 N2 N1 N0

Bit Number

7-4 R3:0 PLL R Divider Bits

3-0 N3:0 PLL N Divider Bits

Bit

Mnemonic Description

Reset Value = 0000 0000

AT89C5131A-L

SFR Mapping

The Special Function Registers (SFRs) of the AT89C5131A-L fall into the following categories:

• C51 core registers: ACC, B, DPH, DPL, PSW, SP

• I/O port registers: P0, P1, P2, P3, P4

• Timer registers: T2CON, T2MOD, TCON, TH0, TH1, TH2, TMOD, TL0, TL1, TL2, RCAP2L, RCAP2H

• Serial I/O port registers: SADDR, SADEN, SBUF, SCON

• PCA (Programmable Counter Array) registers: CCON, CMOD, CCAPMx, CL, CH, CCAPxH, CCAPxL (x: 0 to 4)

• Power and clock control registers: PCON

• Hardware Watchdog Timer registers: WDTRST, WDTPRG

• Interrupt system registers: IEN0, IPL0, IPH0, IEN1, IPL1, IPH1

• Keyboard Interface registers: KBE, KBF, KBLS

• LED register: LEDCON

• Two Wire Interface (TWI) registers: SSCON, SSCS, SSDAT, SSADR

• Serial Port Interface (SPI) registers: SPCON, SPSTA, SPDAT

• USB registers: Uxxx (17 registers)

• PLL registers: PLLCON, PLLDIV

• BRG (Baud Rate Generator) registers: BRL, BDRCON

• Flash register: FCON (FCON access is reserved for the Flash API and ISP software)

• EEPROM register: EECON

• Others: AUXR, AUXR1, CKCON0, CKCON1

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Table 18. SFR Descriptions

Reserved

Bit

Addressable Non-Bit Addressable

0/8 1/9 2/A 3/B 4/C 5/D 6/E 7/F

AT89C5131A-L

The table below shows all SFRs with their address and their reset value.

F8h

F0h

E8h

E0h

D8h

D0h

C8h

C0h

B8h

B0h

UEPINT

0000 0000

ACC

0000 0000

CCON

00X0 0000

PSW

0000 0000

T2CON

0000 0000

XXXX 1111

IPL0

X000 000

1111 1111

0000 0000

LEDCON

0000 0000

CMOD

00XX X000

FCON (1)

XXXX 0000

T2MOD

XXXX XX00

SADEN

0000 0000

IEN1

X0XX X000

CCAP0H

XXXX XXXX

CCAP0L

XXXX XXXX

UBYCTLX

0000 0000

CCAPM0

X000 0000

EECON

XXXX XX00

RCAP2L

0000 0000

UEPIEN

0000 0000

UFNUML

0000 0000

IPL1

X0XX X000

CCAP1H

XXXX XXXX

CCAP1L

XXXX XXXX

UBYCTHX 0000 0000

CCAPM1

X000 0000

RCAP2H

0000 0000

SPCON

0001 0100

UFNUMH

0000 0000

IPH1

X0XX X000

CCAP2H

XXXX XXXX

CCAP2L

XXXX XXXX

CCAPM2

X000 0000

UEPCONX

1000 0000

TL2

0000 0000

SPSTA

0000 0000

USBCON

0000 0000

CCAP3H

XXXX XXXX

CCAP3L

XXXX XXXX

CCAPM3

X000 0000

UEPRST

0000 0000

TH2

0000 0000

SPDAT

XXXX XXXX

USBINT

0000 0000

CCAP4H

XXXX XXXX

CCAP4L

XXXX XXXX

CCAPM4

X000 0000

UEPSTAX

0000 0000

USBADDR 1000 0000

USBIEN

0000 0000

UEPDATX 0000 0000

UEPNUM

0000 0000

IPH0

X000 0000

FFh

F7h

EFh

E7h

DFh

D7h

CFh

C7h

BFh

B7h

A8h

A0h

98h

90h

88h

80h

IEN0

0000 0000

1111 1111

SCON

0000 0000

1111 1111

TCON

0000 0000

1111 1111

0/8 1/9 2/A 3/B 4/C 5/D 6/E 7/F

SADDR

0000 0000

SBUF

XXXX XXXX

TMOD

0000 0000

0000 0111

AUXR1

XXXX X0X0

BRL

0000 0000

TL0

0000 0000

DPL

0000 0000

PLLCON

XXXX XX00

BDRCON

XXX0 0000

SSCON

0000 0000

TL1

0000 0000

DPH

0000 0000

1111 1000

0000 0000

Note: 1. FCON access is reserved for the Flash API and ISP software.

PLLDIV

KBLS

SSCS

TH0

KBE

0000 0000

SSDAT

1111 1111

TH1

0000 0000

WDTRST

XXXX XXXX

KBF

0000 0000

SSADR

1111 1110

AUXR

XX0X 0000

CKCON1

0000 0000

WDTPRG

XXXX X000

CKCON0

0000 0000

PCON

00X1 0000

AFh

A7h

9Fh

97h

8Fh

87h

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AT89C5131A-L

The Special Function Registers (SFRs) of the AT89C5131 fall into the following categories:

Table 19. C51 Core SFRs

Mnemonic Add Name 7 6 5 4 3 2 1 0

ACC E0h Accumulator

B F0h B Register

PSW D0h

SP 81h

DPL 82h

DPH 83h

Program Status Word

Stack Pointer

LSB of SPX

Data Pointer Low byte

LSB of DPTR

Data Pointer High byte

MSB of DPTR

Table 20. I/O Port SFRs

Mnemonic Add Name 7 6 5 4 3 2 1 0

P0 80h Port 0

P1 90h Port 1

P2 A0h Port 2

P3 B0h Port 3

P4 C0h Port 4 (2bits)

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AT89C5131A-L

Table 21. Timer SFR’s

Mnemonic Add Name 7 6 5 4 3 2 1 0

TH0 8Ch Timer/Counter 0 High byte

TL0 8Ah Timer/Counter 0 Low byte

TH1 8Dh Timer/Counter 1 High byte

TL1 8Bh Timer/Counter 1 Low byte

TH2 CDh Timer/Counter 2 High byte

TL2 CCh Timer/Counter 2 Low byte

TCON 88h

TMOD 89h

T2CON C8h Timer/Counter 2 control TF2 EXF2 RCLK TCLK EXEN2 TR2 C/T2# CP/RL2#

T2MOD C9h Timer/Counter 2 Mode T2OE DCEN

RCAP2H CBh

RCAP2L CAh

WDTRST A6h WatchDog Timer Reset

WDTPRG A7h WatchDog Timer Program S2 S1 S0

Timer/Counter 0 and 1 control

Timer/Counter 0 and 1 Modes

Timer/Counter 2 Reload/Capture High byte

Timer/Counter 2 Reload/Capture Low byte

TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

GATE1 C/T1# M11 M01 GATE0 C/T0# M10 M00

Table 22. Serial I/O Port SFR’s

Mnemonic Add Name 7 6 5 4 3 2 1 0

SCON 98h Serial Control FE/SM0 SM1 SM2 REN TB8 RB8 TI RI

SBUF 99h Serial Data Buffer

SADEN B9h Slave Address Mask

SADDR A9h Slave Address

Table 23. Baud Rate Generator SFR’s

Mnemonic Add Name 7 6 5 4 3 2 1 0

BRL 9Ah Baud Rate Reload

BDRCON 9Bh Baud Rate Control BRR TBCK RBCK SPD SRC

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AT89C5131A-L

Table 24. PCA SFR’s

Mnemonic Add Name 7 6 5 4 3 2 1 0

CCON D8h PCA Timer/Counter Control CF CR CCF4 CCF3 CCF2 CCF1 CCF0

CMOD D9h PCA Timer/Counter Mode CIDL WDTE CPS1 CPS0 ECF

CL E9h PCA Timer/Counter Low byte

CH F9h PCA Timer/Counter High byte

CCAPM0 CCAPM1 CCAPM2 CCAPM3 CCAPM4

CCAP0H CCAP1H CCAP2H CCAP3H CCAP4H

CCAP0L CCAP1L CCAP2L CCAP3L CCAP4L

DAh

PCA Timer/Counter Mode 0

DBh

PCA Timer/Counter Mode 1

DCh

PCA Timer/Counter Mode 2

DDh

PCA Timer/Counter Mode 3

DEh

PCA Timer/Counter Mode 4

FAh

PCA Compare Capture Module 0 H

FBh

PCA Compare Capture Module 1 H

FCh

PCA Compare Capture Module 2 H

FDh

PCA Compare Capture Module 3 H

FEh

PCA Compare Capture Module 4 H

EAh

PCA Compare Capture Module 0 L

EBh

PCA Compare Capture Module 1 L

ECh

PCA Compare Capture Module 2 L

EDh

PCA Compare Capture Module 3 L

EEh

PCA Compare Capture Module 4 L

CCAP0H7 CCAP1H7 CCAP2H7 CCAP3H7 CCAP4H7

CCAP0L7 CCAP1L7 CCAP2L7 CCAP3L7 CCAP4L7

ECOM0 ECOM1 ECOM2 ECOM3 ECOM4

CCAP0H6 CCAP1H6 CCAP2H6 CCAP3H6 CCAP4H6

CCAP0L6 CCAP1L6 CCAP2L6 CCAP3L6 CCAP4L6

CAPP0 CAPP1 CAPP2 CAPP3 CAPP4

CCAP0H5 CCAP1H5 CCAP2H5 CCAP3H5 CCAP4H5

CCAP0L5 CCAP1L5 CCAP2L5 CCAP3L5 CCAP4L5

CAPN0 CAPN1 CAPN2 CAPN3 CAPN4

CCAP0H4 CCAP1H4 CCAP2H4 CCAP3H4 CCAP4H4

CCAP0L4 CCAP1L4 CCAP2L4 CCAP3L4 CCAP4L4

MAT0 MAT1 MAT2 MAT3 MAT4

CCAP0H3 CCAP1H3 CCAP2H3 CCAP3H3 CCAP4H3

CCAP0L3 CCAP1L3 CCAP2L3 CCAP3L3 CCAP4L3

TOG0 TOG1 TOG2 TOG3 TOG4

CCAP0H2 CCAP1H2 CCAP2H2 CCAP3H2 CCAP4H2

CCAP0L2 CCAP1L2 CCAP2L2 CCAP3L2 CCAP4L2

PWM0 PWM1 PWM2 PWM3 PWM4

CCAP0H1 CCAP1H1 CCAP2H1 CCAP3H1 CCAP4H1

CCAP0L1 CCAP1L1 CCAP2L1 CCAP3L1 CCAP4L1

ECCF0 ECCF1 ECCF2 ECCF3 ECCF4

CCAP0H0 CCAP1H0 CCAP2H0 CCAP3H0 CCAP4H0

CCAP0L0 CCAP1L0 CCAP2L0 CCAP3L0 CCAP4L0

Table 25. Interrupt SFR’s

Mnemonic Add Name 7 6 5 4 3 2 1 0

IEN0 A8h Interrupt Enable Control 0 EA EC ET2 ES ET1 EX1 ET0 EX0

IEN1 B1h Interrupt Enable Control 1 EUSB ESPI ETWI EKB

IPL0 B8h Interrupt Priority Control Low 0 PPCL PT2L PSL PT1L PX1L PT0L PX0L

IPH0 B7h Interrupt Priority Control High 0 PPCH PT2H PSH PT1H PX1H PT0H PX0H

IPL1 B2h Interrupt Priority Control Low 1 PUSBL PSPIL PTWIL PKBL

IPH1 B3h Interrupt Priority Control High 1 PUSBH PSPIH PTWIH PKBH

Table 26. PLL SFRs

Mnemonic Add Name 7 6 5 4 3 2 1 0

PLLCON A3h PLL Control EXT48 PLLEN PLOCK

PLLDIV A4h PLL Divider R3 R2 R1 R0 N3 N2 N1 N0

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AT89C5131A-L

Table 27. Keyboard SFRs

Mnemonic Add Name 7 6 5 4 3 2 1 0

KBF 9Eh

KBE 9Dh

KBLS 9Ch

Keyboard Flag Register

Keyboard Input Enable Register

Keyboard Level Selector Register

KBF7 KBF6 KBF5 KBF4 KBF3 KBF2 KBF1 KBF0

KBE7 KBE6 KBE5 KBE4 KBE3 KBE2 KBE1 KBE0

KBLS7 KBLS6 KBLS5 KBLS4 KBLS3 KBLS2 KBLS1 KBLS0

Table 28. TWI SFRs

Mnemonic Add Name 7 6 5 4 3 2 1 0

SSCON 93h

SSCS 94h

SSDAT 95h

SSADR 96h

Synchronous Serial Control

Synchronous Serial Control-Status

Synchronous Serial Data

Synchronous Serial Address

CR2 SSIE STA STO SI AA CR1 CR0

SC4 SC3 SC2 SC1 SC0 - - -

SD7 SD6 SD5 SD4 SD3 SD2 SD1 SD0

A7 A6 A5 A4 A3 A2 A1 A0

Table 29. SPI SFRs

Mnemonic Add Name 7 6 5 4 3 2 1 0

SPCON C3h

SPSTA C4h

SPDAT C5h Serial Peripheral Data R7 R6 R5 R4 R3 R2 R1 R0

Serial Peripheral Control

Serial Peripheral Status-Control

SPR2 SPEN SSDIS MSTR CPOL CPHA SPR1 SPR0

SPIF WCOL SSERR MODF - - - -

Table 30. USB SFR’s

Mnemonic Add Name 7 6 5 4 3 2 1 0

USBCON BCh USB Global Control USBE SUSPCLK SDRMWUP DETACH UPRSM RMWUPE CONFG FADDEN

USBADDR C6h USB Address FEN UADD6 UADD5 UADD4 UADD3 UADD2 UADD1 UADD0

USBINT BDh USB Global Interrupt - - WUPCPU EORINT SOFINT - - SPINT

USBIEN BEh

UEPNUM C7h USB Endpoint Number - - - - EPNUM3 EPNUM2 EPNUM1 EPNUM0

UEPCONX D4h USB Endpoint X Control EPEN - - - DTGL EPDIR EPTYPE1 EPTYPE0

UEPSTAX CEh USB Endpoint X Status DIR RXOUTB1 STALLRQ TXRDY STLCRC RXSETUP RXOUTB0 TXCMP

UEPRST D5h USB Endpoint Reset - EP6RST EP5RST EP4RST EP3RST EP2RST EP1RST EP0RST

UEPINT F8h USB Endpoint Interrupt - EP6INT EP5INT EP4INT EP3INT EP2INT EP1INT EP0INT

USB Global Interrupt Enable

- - EWUPCPU EEORINT ESOFINT - - ESPINT

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AT89C5131A-L

Table 30. USB SFR’s

Mnemonic Add Name 7 6 5 4 3 2 1 0

UEPIEN C2h

UEPDATX CFh USB Endpoint X FIFO Data FDAT7 FDAT6 FDAT5 FDAT4 FDAT3 FDAT2 FDAT1 FDAT0

UBYCTLX E2h

UBYCTHX E3h

UFNUML BAh USB Frame Number Low FNUM7 FNUM6 FNUM5 FNUM4 FNUM3 FNUM2 FNUM1 FNUM0

UFNUMH BBh USB Frame Number High - - CRCOK CRCERR - FNUM10 FNUM9 FNUM8

USB Endpoint Interrupt Enable

USB Byte Counter Low (EP X)

USB Byte Counter High (EP X)

- EP6INTE EP5INTE EP4INTE EP3INTE EP2INTE EP1INTE EP0INTE

BYCT7 BYCT6 BYCT5 BYCT4 BYCT3 BYCT2 BYCT1 BYCT0

- - - - - BYCT10 BYCT9 BYCT8

Table 31. Other SFR’s

Mnemonic Add Name 7 6 5 4 3 2 1 0

PCON 87h Power Control SMOD1 SMOD0 - POF GF1 GF0 PD IDL

AUXR 8Eh Auxiliary Register 0 DPU - M0 - XRS1 XRS2 EXTRAM A0

AUXR1 A2h Auxiliary Register 1 - - ENBOOT - GF3 - - DPS

CKCON0 8Fh Clock Control 0 TWIX2 WDX2 PCAX2 SIX2 T2X2 T1X2 T0X2 X2

CKCON1 AFh Clock Control 1 - - - - - - - SPIX2

LEDCON F1h LED Control LED3 LED2 LED1 LED0

FCON D1h Flash Control FPL3 FPL2 FPL1 FPL0 FPS FMOD1 FMOD0 FBUSY

EECON D2h EEPROM Contol EEPL3 EEPL2 EEPL1 EEPL0 - - EEE EEBUSY

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AT89C5131A-L

External Data Memory

AUXR1(A2H)

DPS

DPH(83H) DPL(82H)

DPTR0

DPTR1

Dual Data Pointer Register

Figure 12. Use of Dual Pointer

The additional data pointer can be used to speed up code execution and reduce code size.

The dual DPTR structure is a way by which the chip will specify the address of an external data memory location. There are two 16-bit DPTR registers that address the external memory, and a single bit called DPS = AUXR1.0 (see Table 32) that allows the program code to switch between them (see Figure 12).

Table 32. AUXR1 Register AUXR1- Auxiliary Register 1(0A2h)

7 6 5 4 3 2 1 0

- - ENBOOT - GF3 0 - DPS

Bit

Number

7 -

6 -

5 ENBOOT

4 -

3 GF3 This bit is a general-purpose user flag.

2 0 Always cleared.

1 -

0 DPS

Bit

Mnemonic Description

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Enable Boot Flash

Cleared to disable boot ROM.

Set to map the boot ROM between F800h - 0FFFFh.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Data Pointer Selection

Cleared to select DPTR0. Set to select DPTR1.

Reset Value = XX[BLJB]X X0X0b Not bit addressable

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a. Bit 2 stuck at 0; this allows to use INC AUXR1 to toggle DPS without changing GF3.

AT89C5131A-L

ASSEMBLY LANGUAGE

; Block move using dual data pointers ; Modifies DPTR0, DPTR1, A and PSW ; note: DPS exits opposite of entry state ; unless an extra INC AUXR1 is added ; 00A2 AUXR1 EQU 0A2H ; 0000 909000MOV DPTR,#SOURCE ; address of SOURCE 0003 05A2 INC AUXR1 ; switch data pointers 0005 90A000 MOV DPTR,#DEST ; address of DEST 0008 LOOP: 0008 05A2 INC AUXR1 ; switch data pointers 000A E0 MOVX A,@DPTR ; get a byte from SOURCE 000B A3 INC DPTR ; increment SOURCE address 000C 05A2 INC AUXR1 ; switch data pointers 000E F0 MOVX @DPTR,A ; write the byte to DEST 000F A3 INC DPTR ; increment DEST address 0010 70F6JNZ LOOP ; check for 0 terminator 0012 05A2 INC AUXR1 ; (optional) restore DPS

INC is a short (2 bytes) and fast (12 clocks) way to manipulate the DPS bit in the AUXR1 SFR. However, note that the INC instruction does not directly force the DPS bit to a particular state, but simply toggles it. In simple routines, such as the block move example, only the fact that DPS is toggled in the proper sequence matters, not its actual value. In other words, the block move routine works the same whether DPS is '0' or '1' on entry. Observe that without the last instruction (INC AUXR1), the routine will exit with DPS in the opposite state.

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AT89C5131A-L

0000h

32 Kbytes

7FFFh

Flash

32 Kbytes

External Code

FFFFh

AT89C5131A-L

8000h

Flash

EPROM

AT89C5131

AD7:0

A15:8

A7:0

A15:8

D7:0

A7:0

ALE

Latch

OEPSEN

Program/Code Memory

The AT89C5131A-L implement 32 Kbytes of on-chip program/code memory. Figure 13 shows the split of internal and external program/code memory spaces depending on the product.

The Flash memory increases EPROM and ROM functionality by in-circuit electrical erasure and programming. Thanks to the internal charge pump, the high voltage needed for programming or erasing Flash cells is generated on-chip using the standard VDD voltage. Thus, the Flash Memory can be programmed using only one voltage and allows Inapplication Software Programming commonly known as IAP. Hardware programming mode is also available using specific programming tool.

Figure 13. Program/Code Memory Organization

Note: If the program executes exclusively from on-chip code memory (not from external mem-

ory), beware of executing code from the upper byte of on-chip memory (7FFFh) and thereby disrupting I/O Ports 0 and 2 due to external prefetch. Fetching code constant from this location does not affect Ports 0 and 2.

External Code Memory Access

Memory Interface The external memory interface comprises the external bus (Port 0 and Port 2) as well as

the bus control signals (PSEN, and ALE).

Figure 14 shows the structure of the external address bus. P0 carries address A7:0 while P2 carries address A15:8. Data D7:0 is multiplexed with A7:0 on P0. Table 33 describes the external memory interface signals.

Figure 14. External Code Memory Interface Structure

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AT89C5131A-L

Table 33. External Data Memory Interface Signals

ALE

PSEN

PCL

PCHPCH

PCLD7:0 D7:0

PCH

D7:0

CPU Clock

Signal Name Type Description

A15:8 O

AD7:0 I/O

ALE O

PSEN O

Address Lines

Upper address lines for the external bus.

Address/Data Lines

Multiplexed lower address lines and data for the external memory.

Address Latch Enable

ALE signals indicates that valid address information are available on lines AD7:0.

Program Store Enable Output

This signal is active low during external code fetch or external code read (MOVC instruction).

Alternate Function

P2.7:0

P0.7:0

External Bus Cycles This section describes the bus cycles the AT89C5131A-L executes to fetch code (see

Figure 15) in the external program/code memory.

External memory cycle takes 6 CPU clock periods. This is equivalent to 12 oscillator clock periods in standard mode or 6 oscillator clock periods in X2 mode. For further information on X2 mode (see the clock Section).

For simplicity, the accompanying figure depicts the bus cycle waveforms in idealized form and do not provide precise timing information.

Figure 15. External Code Fetch Waveforms

Flash Memory Architecture

AT89C5131A-L features two on-chip Flash memories:

• Flash memory FM0: containing 32 Kbytes of program memory (user space) organized into 128-byte pages,

• Flash memory FM1: 3 Kbytes for bootloader and Application Programming Interfaces (API).

The FM0 supports both parallel programming and Serial In-System Programming (ISP) whereas FM1 supports only parallel programming by programmers. The ISP mode is detailed in the “In-System Programming” section.

All Read/Write access operations on Flash memory by user application are managed by a set of API described in the “In-System Programming” section.

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Figure 16. Flash Memory Architecture

7FFFh

32 Kbytes

Flash Memory

FM0

0000h

Hardware Security (1 Byte)

Column Latches (128 Bytes)

User Space

Extra Row (128 Bytes)

3 Kbytes

Flash Memory

FM1

Boot Space

FFFFh

F400h

FM1 mapped between FFFFh and F400h when bit ENBOOT is set in AUXR1 register

FM0 Memory Architecture The Flash memory is made up of 4 blocks (see Figure 16):

1. The memory array (user space) 32 Kbytes

2. The Extra Row

3. The Hardware security bits

4. The column latch registers

AT89C5131A-L

User Space This space is composed of a 32 Kbytes Flash memory organized in 256 pages of 128

bytes. It contains the user’s application code.

Extra Row (XRow) This row is a part of FM0 and has a size of 128 bytes. The extra row contains informa-

tion for bootloader usage. (see Table 39.Software Registers, page 39)

Hardware Security Space The hardware security space is a part of FM0 and has a size of 1 byte.

The 4 MSB can be read/written by software. The 4 LSB can only be read by software and written by hardware in parallel mode.

Column Latches The column latches, also part of FM0, have a size of full page (128 bytes).

The column latches are the entrance buffers of the three previous memory locations (user array, XRow and Hardware security byte).

Overview of FM0 Operations

The CPU interfaces to the Flash memory through the FCON register and AUXR1 register.

These registers are used to:

• Map the memory spaces in the adressable space

• Launch the programming of the memory spaces

• Get the status of the Flash memory (busy/not busy)

• Select the Flash memory FM0/FM1.

Mapping of the Memory Space By default, the user space is accessed by MOVC instruction for read only. The column

latches space is made accessible by setting the FPS bit in FCON register. Writing is possible from 0000h to 7FFFh, address bits 6 to 0 are used to select an address within a

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page while bits 14 to 7 are used to select the programming address of the page.

Setting this bit takes precedence on the EXTRAM bit in AUXR register.

AT89C5131A-L

The other memory spaces (user, extra row, hardware security) are made accessible in the code segment by programming bits FMOD0 and FMOD1 in FCON register in accordance with Table 34. A MOVC instruction is then used for reading these spaces.

Table 34. FM0 Blocks Select Bits

FMOD1 FMOD0 FM0 Adressable Space

0 0 User (0000h-FFFFh)

0 1 Extra Row(FF80h-FFFFh)

1 0 Hardware Security (0000h)

1 1 reserved

Launching Programming FPL3:0 bits in FCON register are used to secure the launch of programming. A specific

sequence must be written in these bits to unlock the write protection and to launch the programming. This sequence is 5 followed by A. Table 35 summarizes the memory spaces to program according to FMOD1:0 bits.

Table 35. Programming Spaces

Write to FCON

OperationFPL3:0 FPS FMOD1 FMOD0

5 X 0 0 No action

User

Extra Row

Security

Space

Reserved

A X 0 0

5 X 0 1 No action

A X 0 1

5 X 1 0 No action

A X 1 0 Write the fuse bits space

5 X 1 1 No action

A X 1 1 No action

Write the column latches in user space

Write the column latches in extra row space

The Flash memory enters a busy state as soon as programming is launched. In this state, the memory is not available for fetching code. Thus to avoid any erratic execution during programming, the CPU enters Idle mode. Exit is automatically performed at the end of programming.

Note: Interrupts that may occur during programming time must be disabled to avoid any spuri-

ous exit of the idle mode.

Status of the Flash Memory The bit FBUSY in FCON register is used to indicate the status of programming.

FBUSY is set when programming is in progress.

Selecting FM0/FM1 The bit ENBOOT in AUXR1 register is used to choose between FM0 and FM1 mapped

up to F800h.

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AT89C5131A-L

Column Latches

Data Load

DPTR = Address

ACC = Data

Exec: MOVX @DPTR, A

Last Byte

to load?

Column Latches Mapping

FPS = 1

Data memory Mapping

FPS = 0

Loading the Column Latches Any number of data from 1 byte to 128 bytes can be loaded in the column latches. This

provides the capability to program the whole memory by byte, by page or by any number of bytes in a page.

When programming is launched, an automatic erase of the locations loaded in the column latches is first performed, then programming is effectively done. Thus, no page or block erase is needed and only the loaded data are programmed in the corresponding page.

The following procedure is used to load the column latches and is summarized in Figure 17:

• Map the column latch space by setting FPS bit.

• Load the DPTR with the address to load.

• Load Accumulator register with the data to load.

• Execute the MOVX @DPTR, A instruction.

• If needed loop the three last instructions until the page is completely loaded.

Figure 17. Column Latches Loading Procedure

Programming the Flash Spaces

User The following procedure is used to program the User space and is summarized in

Figure 18:

• Load data in the column latches from address 0000h to 7FFFh

(1)

• Disable the interrupts.

• Launch the programming by writing the data sequence 50h followed by A0h in FCON register. The end of the programming indicated by the FBUSY flag cleared.

• Enable the interrupts.

Note: 1. The last page address used when loading the column latch is the one used to select

the page programming address.

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AT89C5131A-L

Extra Row The following procedure is used to program the Extra Row space and is summarized in

Flash Spaces

Programming

Disable IT

EA = 0

Launch Programming

FCON = 5xh FCON = Axh

End Programming

Enable IT

EA = 1

Column Latches Loading

see Figure 17

FBusy

Cleared?

Erase Mode

FCON = 00h

Figure 18:

• Load data in the column latches from address FF80h to FFFFh.

• Disable the interrupts.

• Launch the programming by writing the data sequence 52h followed by A2h in FCON register. The end of the programming indicated by the FBUSY flag cleared.

• Enable the interrupts.

Figure 18. Flash and Extra Row Programming Procedure

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AT89C5131A-L

Flash Spaces

Programming

Disable IT

EA = 0

Launch Programming

FCON = 54h

FCON = A4h

End Programming

Enable IT

EA = 1

FBusy

Cleared?

Erase Mode

FCON = 00h

Data Load

DPTR = 00h ACC = Data

Exec: MOVX @DPTR, A

FCON = 0Ch

Hardware Security The following procedure is used to program the Hardware Security space and is sum-

marized in Figure 19:

• Set FPS and map Hardware byte (FCON = 0x0C)

• Disable the interrupts.

• Load DPTR at address 0000h.

• Load Accumulator register with the data to load.

• Execute the MOVX @DPTR, A instruction.

• Launch the programming by writing the data sequence 54h followed by A4h in FCON register. The end of the programming indicated by the FBusy flag cleared.

• Enable the interrupts.

Figure 19. Hardware Programming Procedure

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Reading the Flash Spaces

Flash Spaces Reading

Flash Spaces Mapping

FCON = 00000xx0b

Data Read

DPTR = Address

ACC = 0

Exec: MOVC A, @A+DPTR

Erase Mode

FCON = 00h

User The following procedure is used to read the User space and is summarized in Figure 20:

• Map the User space by writing 00h in FCON register.

• Read one byte in Accumulator by executing MOVC A, @A+DPTR with A = 0 & DPTR = 0000h to FFFFh.

Extra Row The following procedure is used to read the Extra Row space and is summarized in

Figure 20:

• Map the Extra Row space by writing 02h in FCON register.

• Read one byte in Accumulator by executing MOVC A, @A+DPTR with A = 0 & DPTR = FF80h to FFFFh.

Hardware Security The following procedure is used to read the Hardware Security space and is summa-

rized in Figure 20:

• Map the Hardware Security space by writing 04h in FCON register.

• Read the byte in Accumulator by executing MOVC A, @A+DPTR with A = 0 & DPTR = 0000h.

Figure 20. Reading Procedure

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AT89C5131A-L

Registers

Table 36. FCON (S:D1h)

Flash Control Register

7 6 5 4 3 2 1 0

FPL3 FPL2 FPL1 FPL0 FPS FMOD1 FMOD0 FBUSY

Bit Number

7-4 FPL3:0

3 FPS

2-1 FMOD1:0

0 FBUSY

Bit

Mnemonic Description

Programming Launch Command Bits

Write 5Xh followed by AXh to launch the programming according to FMOD1:0. (see Table 35.)

Flash Map Program Space

Set to map the column latch space in the data memory space. Clear to re-map the data memory space.

Flash Mode

See Table 34 or Table 35.

Flash Busy

Set by hardware when programming is in progress. Clear by hardware when programming is done. Can not be cleared by software.

Reset Value = 0000 0000b

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Flash EEPROM Memory

General Description

Features

The Flash memory increases EPROM functionality with in-circuit electrical erasure and programming. It contains 32 Kbytes of program memory organized in 256 pages of 128 bytes, respectively. This memory is both parallel and serial In-System Programmable (ISP). ISP allows devices to alter their own program memory in the actual end product under software control. A default serial loader (bootloader) program allows ISP of the Flash.

The programming does not require 12V external programming voltage. The necessary high programming voltage is generated on-chip using the standard VCC pins of the microcontroller.

• Flash EEPROM internal program memory.

• Boot vector allows user-provided Flash loader code to reside anywhere in the Flash memory space. This configuration provides flexibility to the user.

• Default loader in Boot EEPROM allows programming via the serial port without the need of a user provided loader.

• Up to 64K bytes external program memory if the internal program memory is disabled (EA = 0).

• Programming and erase voltage with standard power supply.

• Read/Program/Erase:

• Byte-wise read (without wait state).

• Byte or page erase and programming (10 ms).

• Typical programming time (32 Kbytes) in 10 sec.

• Parallel programming with 87C51 compatible hardware interface to programmer.

• Programmable security for the code in the Flash.

• 100K write cycles

• 10 years data retention

Flash Programming and Erasure

The 32 Kbytes Flash is programmed by bytes or by pages of 128 bytes. It is not necessary to erase a byte or a page before programming. The programming of a byte or a page includes a self erase before programming.

There are three methods of programming the Flash memory:

1. The on-chip ISP bootloader may be invoked which will use low level routines to program the pages. The interface used for serial downloading of Flash is the USB.

2. The Flash may be programmed or erased in the end-user application by calling low-level routines through a common entry point in the Boot Flash.

3. The Flash may be programmed using the parallel method .

The bootloader and the Application Programming Interface (API) routines are located in the Flash Bootloader.

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Flash Registers and Memory Map

The AT89C5131A-L Flash memory uses several registers:

• Hardware register can be accessed with a parallel programmer.Some bits of the hardware register can be changed, also, by API (i.e. X2 and BLJB bits of Hardware security Byte) or ISP.

• Software registers are in a special page of the Flash memory which can be accessed through the API or with the parallel programming modes. This page, called “Extra Flash Memory”, is not in the internal Flash program memory addressing space.

Hardware Registers The only hardware register of the AT89C5131A-L is called Hardware Security Byte

(HSB).

Table 37. Hardware Security Byte (HSB)

7 6 5 4 3 2 1 0

X2 BLJB OSCON1 OSCON0 - LB2 LB1 LB0

Bit

Number

7 X2

6 BLJB

Bit

Mnemonic Description

X2 Mode

Cleared to force X2 mode (6 clocks per instruction)

Set to force X1 mode, Standard Mode (Default).

Bootloader Jump Bit

Set this bit to start the user’s application on next reset at address 0000h.

Cleared this bit to start the bootloader at address F400h (default).

Oscillator Control Bits

These two bits are used to control the oscillator in order to reduce consumption.

5-4 OSCON1-0

3 - Reserved

2-0 LB2-0

OSCON1 OSCON0 Description

1 1 The oscillator is configured to run from 0 to 32 MHz 1 0 The oscillator is configured to run from 0 to 16 MHz 0 1 The oscillator is configured to run from 0 to 8 MHz 0 0 This configuration shouldn’t be set

User Memory Lock Bits

See Table 38

Bootloader Jump Bit (BLJB) One bit of the HSB, the BLJB bit, is used to force the boot address:

• When this bit is set the boot address is 0000h.

• When this bit is reset the boot address is F400h. By default, this bit is cleared and the ISP is enabled.

Flash Memory Lock Bits The three lock bits provide different levels of protection for the on-chip code and data,

when programmed as shown in Table 38.

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Table 38. Program Lock bits

Program Lock Bits

Protection DescriptionSecurity level LB0 LB1 LB2

1 U U U No program lock features enabled.

MOVC instruction executed from external program memory is disabled from fetching code

2 P U U

3 X P U

4 X X P Same as 3, also external execution is disabled.

Notes: 1. U: unprogrammed or “one” level.

2. P: programmed or “zero” level.

3. X: don’t care

4. WARNING: Security level 2 and 3 should only be programmed after verification.

bytes from any internal memory, EA is sampled and latched on reset, and further parallel programming of the Flash and of the EEPROM (boot and Xdata) is disabled. ISP and software programming with API are still allowed.

Same as 2, also verify through parallel programming interface is disabled and serial programming ISP is still allowed.

These security bits protect the code access through the parallel programming interface. They are set by default to level 4. The code access through the ISP is still possible and is controlled by the “software security bits” which are stored in the extra Flash memory accessed by the ISP firmware.

To load a new application with the parallel programmer, a chip erase must be done first. This will set the HSB in its inactive state and will erase the Flash memory. The part reference can always be read using Flash parallel programming modes.

Default Values The default value of the HSB provides parts ready to be programmed with ISP:

• BLJB: Cleared to force ISP operation.

• X2: Set to force X1 mode (Standard Mode)

• OSCON1-0: Set to start with 32 MHz oscillator configuration value.

• LB2-0: Security level four to protect the code from a parallel access with maximum security.

Software Registers Several registers are used, in factory and by parallel programmers, to make copies of

hardware registers contents. These values are used by Atmel ISP (see Section “In-System Programming (ISP)”).

These registers are in the “Extra Flash Memory” part of the Flash memory. This block is also called ”XAF” or eXtra Array Flash. They are accessed in the following ways:

• Commands issued by the parallel memory programmer.

• Commands issued by the ISP software.

• Calls of API issued by the application software.

Several software registers are described in Table 39.

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Table 39. Software Registers

Address Mnemonic Description Default value

01 SBV Software Boot Vector FFh –

00 BSB Boot Status Byte 0FFh –

05 SSB Software Security Byte FFh –

30 –

31 –

60 –

61 –

Copy of the Manufacturer Code

Copy of the Device ID #1: Family Code

Copy of the Device ID #2: Memories

Copy of the Device ID #3: Name

58h Atmel

D7h

F7h AT89C5131A-L 32 Kbyte

DFh

C51 X2, Electrically Erasable

AT89C5131A-L 32 Kbyte, revision 0

After programming the part by ISP, the BSB must be cleared (00h) in order to allow the application to boot at 0000h.

The content of the Software Security Byte (SSB) is described in Table 40

and

Table 41.

To assure code protection from a parallel access, the HSB must also be at the required level.

Table 40. Software Security Byte (SSB)

7 6 5 4 3 2 1 0

- - - - - - LB1 LB0

Bit

Number

7 -

Bit

Mnemonic Description

Reserved Do not clear this bit.

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6 -

5 -

4 -

3 -

2 -

1-0 LB1-0

Reserved Do not clear this bit.

User Memory Lock Bits

See Table 41

The two lock bits provide different levels of protection for the on-chip code and data, when programmed as shown to Table 41.

AT89C5131A-L

Table 41. Program Lock Bits of the SSB

0000h

Virgin

Default

Virgin

After ISP

After parallel programming

ApplicationApplication

After ISP

Dedicated ISP

7FFFh

AT89C5131A-M

Application

Virgin

Application

Virgin

Application

Program Lock Bits

Security

Level LB0 LB1

1 U U No program lock features enabled.

2 P U ISP programming of the Flash is disabled.

3 P P Same as 2, also verify through ISP programming interface is disabled.

Notes: 1. U: unprogrammed or "one" level.

2. P: programmed or “zero” level.

3. WARNING: Security level 2 and 3 should only be programmed after Flash and code verification.

Protection Description

Flash Memory Status

AT89C5131A-L parts are delivered with the ISP boot in the Flash memory. After ISP or parallel programming, the possible contents of the Flash memory are summarized in Figure 21:

Figure 21. Flash Memory Possible Contents

Memory Organization

In the AT89C5131A-L, the lowest 32K of the 64 Kbyte program memory address space is filled by internal Flash. When the EA is pin high, the processor fetches instructions from internal program Flash. Bus expansion for accessing program memory from 32K upward is automatic since external instruction fetches occur automatically when the program counter exceeds 7FFFh (32K). If the EA pin is tied low, all program memory fetches are from external memory. If all storage is on chip, then byte location 7FFFh (32K) should be left vacant to prevent and undesired pre-fetch from external program memory address 8000h (32K).

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EEPROM Data Memory

AT89C5131A-L

Description

Write Data in the Column Latches

The 1-Kbyte on-chip EEPROM memory block is located at addresses 0000h to 03FFh of the ERAM memory space and is selected by setting control bits in the EECON register.

A read in the EEPROM memory is done with a MOVX instruction.

A physical write in the EEPROM memory is done in two steps: write data in the column latches and transfer of all data latches into an EEPROM memory row (programming).

The number of data written on the page may vary from 1 to 128 bytes (the page size). When programming, only the data written in the column latch is programmed and a ninth bit is used to obtain this feature. This provides the capability to program the whole memory by bytes, by page or by a number of bytes in a page. Indeed, each ninth bit is set when the writing the corresponding byte in a row and all these ninth bits are reset after the writing of the complete EEPROM row.

Data is written by byte to the column latches as for an external RAM memory. Out of the 11 address bits of the data pointer, the 4 MSBs are used for page selection (row) and 7 are used for byte selection. Between two EEPROM programming sessions, all the addresses in the column latches must stay on the same page, meaning that the 4 MSB must not be changed.

The following procedure is used to write to the column latches:

• Set bit EEE of EECON register

• Load DPTR with the address to write

• Store A register with the data to be written

• Execute a MOVX @DPTR, A

• If needed, loop the three last instructions until the end of a 128 bytes page

Programming

Read Data

The EEPROM programming consists on the following actions:

• Writing one or more bytes of one page in the column latches. Normally, all bytes must belong to the same page; if not, the first page address will be latched and the others discarded.

• Launching programming by writing the control sequence (52h followed by A2h) to the EECON register.

• EEBUSY flag in EECON is then set by hardware to indicate that programming is in progress and that the EEPROM segment is not available for reading.

• The end of programming is indicated by a hardware clear of the EEBUSY flag.

The following procedure is used to read the data stored in the EEPROM memory:

• Set bit EEE of EECON register

• Stretch the MOVX to accommodate the slow access time of the column latch (Set bit M0 of AUXR register)

• Load DPTR with the address to read

• Execute a MOVX A, @DPTR

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Registers

Table 42. EECON (S:0D2h)

EECON Register

7 6 5 4 3 2 1 0

EEPL3 EEPL2 EEPL1 EEPL0 - - EEE EEBUSY

Bit

Bit Number

Mnemonic Description

7-4 EEPL3-0

3 -

2 -

1 EEE

0 EEBUSY

Programming Launch command bits

Write 5Xh followed by AXh to EEPL to launch the programming.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Enable EEPROM Space bit

Set to map the EEPROM space during MOVX instructions (Write in the column latches) Clear to map the ERAM space during MOVX.

Programming Busy flag

Set by hardware when programming is in progress. Cleared by hardware when programming is done. Cannot be set or cleared by software.

Reset Value = XXXX XX00b Not bit addressable

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AT89C5131A-L

F400h

7FFFh

32K Bytes

Flash Memory

3K Bytes IAP

Bootloader

FM0

FM1

Custom Bootloader

[SBV]00h

FFFFh

FM1 Mapped between F400h and FFFFh when API Called

0000h

In-System Programming (ISP)

Flash Programming and Erasure

With the implementation of the User Space (FM0) and the Boot Space (FM1) in Flash technology the AT89C5131 allows the system engineer the development of applications with a very high level of flexibility. This flexibility is based on the possibility to alter the customer program at any stages of a product’s life:

• Before mounting the chip on the PCB, FM0 flash can be programmed with the application code. FM1 is always preprogrammed by Atmel with a USB bootloader.

• Once the chip is mounted on the PCB, it can be programmed by serial mode via the USB bus.

Note: 1. The user can also program his own bootloader in FM1.

This ISP allows code modification over the total lifetime of the product.

Besides the default Bootloaders Atmel provide customers all the needed ApplicationProgramming-Interfaces (API) which are needed for the ISP. The API are located in the Boot memory.

This allow the customer to have a full use of the 32-Kbyte user memory.

There are three methods for programming the Flash memory:

• The Atmel bootloader located in FM1 is activated by the application. Low level API routines (located in FM1)will be used to program FM0. The interface used for serial downloading to FM0 is the USB. API can be called also by user’s bootloader located in FM0 at [SBV]00h.

• A further method exist in activating the Atmel boot loader by hardware activation. See the Section “Hardware Registers”.

• The FM0 can be programmed also by the parallel mode using a programmer.

(1)

Figure 22. Flash Memory Mapping

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Boot Process

RESET

BLJB == 0

Hardware

Software

Bootloader in FM1

Application in FM0

bit ENBOOT in AUXR1 Register Is Initialized with BLJB Inverted.

ENBOOT = 0 PC = 0000h

ENBOOT = 1 PC = F400h

Example, if BLJB=0, ENBOOT

is set (=1) during reset, thus the bootloader is executed after the

reset.

Software Boot Process Example

Many algorithms can be used for the software boot process. Below are descriptions of the different flags and Bytes.

Boot Loader Jump bit (BLJB):

- This bit indicates if on RESET the user wants to jump to this application at address

@0000h on FM0 or execute the boot loader at address @F400h on FM1.

- BLJB = 0 (i.e. bootloader FM1 executed after a reset) is the default Atmel factory pro-

gramming.

-To read or modify this bit, the APIs are used.

Boot Vector Address (SBV):

- This byte contains the MSB of the user boot loader address in FM0.

- The default value of SBV is FFh (no user boot loader in FM0).

- To read or modify this byte, the APIs are used.

Extra Byte (EB) & Boot Status Byte (BSB):

- These Bytes are reserved for customer use.

- To read or modify these Bytes, the APIs are used.

Figure 23. Hardware Boot Process Algorithm

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ALE

VCC

/PSEN

/RST

GND

Unconnected

VCC

VSS

VCC

GND

Crystal

GND

XTAL2

XTAL1

Bootloader

GND

ApplicationProgramming-Interface

XROW Bytes

Hardware Conditions

Several Application Program Interface (API) calls are available for use by an application program to permit selective erasing and programming of Flash pages. All calls are made by functions.

All these APIs are described in detail in the following document on the Atmel web site.

– Datasheet Bootloader USB AT89C5131.

The EXTRA ROW (XROW) includes 128 bytes. Some of these bytes are used for specific purpose in conjonction with the bootloader.

Table 43. XROW Mapping

Description Default Value Address

Copy of the Manufacturer Code 58h 30h

Copy of the Device ID#1: Family code D7h 31h

Copy of the Device ID#2: Memories size and type BBh 60h

Copy of the Device ID#3: Name and Revision FFh 61h

It is possible to force the controller to execute the bootloader after a Reset with hardware conditions. Depending on the product type (low pin count or high pin count package), there are two methods to apply the hardware conditions.

High Pin Count Hardware Conditions (PLCC52, QFP64)

For high pin count packages, the hardware conditons (EA = 1, PSEN = 0) are sampled during the RESET rising edge to force the on-chip bootloader execution (See Figure 82 on page 172). In this way the bootloader can be carried out regardless of the user Flash memory content. It is recommended to pull the PSEN pin down to ground though a 1K resistor to prevent the PSEN pin from being damaged (See Figure 24 below).

Figure 24. ISP Hardware conditions

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AT89C5131A-L

As PSEN is an output port in normal operating mode (running user application or bootloader code) after reset, it is recommended to release PSEN after rising edge of reset signal.

Low Pin Count Hardware Conditions (SOIC28)

Low pin count products do not have PSEN signal, thus for these products, the bootloader is always executed after reset thanks to the BLJB bit. The Hardware Conditions are detected at the begining of the bootloader execution from reset.

The default factory Hardware Condition is assigned to port P1.

• P1 must be equal to FEh

In order to offer the best flexibility, the user can define its own Hardware Condition on one of the following Ports:

• Port1

• Port3

• Port4 (only bit0 and bit1)

The Hardware Conditions configuration is stored in three bytes called P1_CF, P3_CF, P4_CF.

These bytes can be modified by the user through a set of API or through an ISP command.

Note: 1. The BLJB must be at 0 (programmed) to be able to restart the bootloader.

2. BLJB can always be changed by the means of API, whether it's a low or high pin count package.But for a low pin count version, if BLJB=1, no ISP via the Bootloader is further possible (because the HW conditions are never evaluated, as described in the USB Bootloader Datasheet). To go back to ISP, BLJB needs to be changed by a parallel programmer(or by the APIs).

See a detailed description in the applicable Document.

– Datasheet Bootloader USB AT89C5131.

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ERAM

Upper

128 bytes

Internal

RAM

Lower

128 bytes

Internal

RAM

Special Function Register

80h 80h

0FFh or 3FFh(*)

0FFh

External

Data

Memory

0000

00FFh up to 03FFh (*)

0FFFFh

indirect accesses

direct accesses

direct or indirect

accesses

7Fh

(*) Depends on XRS1..0

On-chip Expanded RAM (ERAM)

The AT89C5131A-L provides additional Bytes of random access memory (RAM) space for increased data parameters handling and high level language usage.

AT89C5131A-L devices have an expanded RAM in the external data space; maximum size and location are described in Table 44.

Table 44. Description of Expanded RAM

Address

Part Number ERAM Size

AT89C5131A-L 1024 00h 3FFh

Start End

The AT89C5131A-L has on-chip data memory which is mapped into the following four separate segments.

1. The Lower 128 bytes of RAM (addresses 00h to 7Fh) are directly and indirectly addressable.

2. The Upper 128 bytes of RAM (addresses 80h to FFh) are indirectly addressable only.

3. The Special Function Registers, SFRs, (addresses 80h to FFh) are directly addressable only.

4. The expanded RAM bytes are indirectly accessed by MOVX instructions, and with the EXTRAM bit cleared in the AUXR register (see Table 44)

The lower 128 bytes can be accessed by either direct or indirect addressing. The Upper 128 bytes can be accessed by indirect addressing only. The Upper 128 bytes occupy the same address space as the SFR. That means they have the same address, but are physically separate from SFR space.

Figure 25. Internal and External Data Memory Address

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When an instruction accesses an internal location above address 7Fh, the CPU knows whether the access is to the upper 128 bytes of data RAM or to SFR space by the addressing mode used in the instruction.

• Instructions that use direct addressing access SFR space. For example: MOV 0A0H, # data, accesses the SFR at location 0A0h (which is P2).

• Instructions that use indirect addressing access the Upper 128 bytes of data RAM. For example: MOV atR0, # data where R0 contains 0A0h, accesses the data byte at address 0A0h, rather than P2 (whose address is 0A0h).

• The ERAM bytes can be accessed by indirect addressing, with EXTRAM bit cleared and MOVX instructions. This part of memory which is physically located on-chip, logically occupies the first bytes of external data memory. The bits XRS0 and XRS1 are used to hide a part of the available ERAM as explained in Table 44. This can be useful if external peripherals are mapped at addresses already used by the internal ERAM.

• With EXTRAM = 0, the ERAM is indirectly addressed, using the MOVX instruction in combination with any of the registers R0, R1 of the selected bank or DPTR. An access to ERAM will not affect ports P0, P2, P3.6 (WR) and P3.7 (RD). For example, with EXTRAM = 0, MOVX atR0, # data where R0 contains 0A0H, accesses the ERAM at address 0A0H rather than external memory. An access to external data memory locations higher than the accessible size of the ERAM will be performed with the MOVX DPTR instructions in the same way as in the standard 80C51, with P0 and P2 as data/address busses, and P3.6 and P3.7 as write and read timing signals. Accesses to ERAM above 0FFH can only be done by the use of DPTR.

• With EXTRAM = 1, MOVX @Ri and MOVX @DPTR will be similar to the standard 80C51. MOVX at Ri will provide an eight-bit address multiplexed with data on Port0 and any output port pins can be used to output higher order address bits. This is to provide the external paging capability. MOVX @DPTR will generate a sixteen-bit address. Port2 outputs the high-order eight address bits (the contents of DPH) while Port0 multiplexes the low-order eight address bits (DPL) with data. MOVX at Ri and MOVX @DPTR will generate either read or write signals on P3.6 (WR) and P3.7 (RD).

The stack pointer (SP) may be located anywhere in the 256 bytes RAM (lower and upper RAM) internal data memory. The stack may not be located in the ERAM.

The M0 bit allows to stretch the ERAM timings; if M0 is set, the read and write pulses are extended from 6 to 30 clock periods. This is useful to access external slow peripherals.

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AT89C5131A-L

Table 45. AUXR Register

AUXR - Auxiliary Register (8Eh)

7 6 5 4 3 2 1 0

DPU - M0 - XRS1 XRS0 EXTRAM AO

Bit

Number

7 DPU

6 -

5 M0

4 -

3 XRS1

2 XRS0

1 EXTRAM

Mnemonic Description

Bit

Disable Weak Pull Up

Cleared to enabled weak pull up on standard Ports. Set to disable weak pull up on standard Ports.

Reserved

The value read from this bit is indeterminate. Do not set this bit

Pulse length

Cleared to stretch MOVX control: the RD and the WR pulse length is 6 clock periods (default).

Set to stretch MOVX control: the RD and the WR pulse length is 30 clock periods.

Reserved

The value read from this bit is indeterminate. Do not set this bit

ERAM Size

XRS1XRS0 ERAM size

0 0 256 bytes

0 1 512 bytes

1 0 768 bytes

1 1 1024 bytes (default)

EXTRAM bit

Cleared to access internal ERAM using MOVX at Ri at DPTR.

Set to access external memory.

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ALE Output bit

0 AO

Cleared, ALE is emitted at a constant rate of 1/6 the oscillator frequency (or 1/3 if X2 mode is used) (default).

Set, ALE is active only when a MOVX or MOVC instruction is used.

Reset Value = 0X0X 1100b Not bit addressable

AT89C5131A-L

Timer 2

Th e Timer 2 in the AT 89C5131A -L is t he standard C52 Time r 2. It is a 16 -bit timer/counter: the count is maintained by two cascaded eight-bit timer registers, TH2 and TL2. It is controlled by T2CON (Table 46) and T2MOD (Table 47) registers. Timer 2 operation is similar to Timer 0 and Timer 1. C/T2 selects F external pin T2 (counter operation) as the timer clock input. Setting TR2 allows TL2 to be incremented by the selected input.

Timer 2 has 3 operating modes: capture, auto reload and Baud Rate Generator. These modes are selected by the combination of RCLK, TCLK and CP/RL2 (T2CON).

Refer to the Atmel 8-bit microcontroller hardware documentation for the description of Capture and Baud Rate Generator Modes.

Timer 2 includes the following enhancements:

• Auto-reload mode with up or down counter

• Programmable Clock-output

/12 (timer operation) or

OSC

Auto-reload Mode

The Auto-reload mode configures Timer 2 as a 16-bit timer or event counter with automatic reload. If DCEN bit in T2MOD is cleared, Timer 2 behaves as in 80C52 (refer to the Atmel 8-bit microcontroller hardware description). If DCEN bit is set, Timer 2 acts as an Up/down timer/counter as shown in Figure 26. In this mode the T2EX pin controls the direction of count.

When T2EX is high, Timer 2 counts up. Timer overflow occurs at FFFFh which sets the TF2 flag and generates an interrupt request. The overflow also causes the 16-bit value in RCAP2H and RCAP2L registers to be loaded into the timer registers TH2 and TL2.

When T2EX is low, Timer 2 counts down. Timer underflow occurs when the count in the timer registers TH2 and TL2 equals the value stored in RCAP2H and RCAP2L registers. The underflow sets TF2 flag and reloads FFFFh into the timer registers.

The EXF2 bit toggles when Timer 2 overflows or underflows according to the direction of the count. EXF2 does not generate any interrupt. This bit can be used to provide 17-bit resolution.

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Figure 26. Auto-reload Mode Up/Down Counter (DCEN = 1)

(DOWN COUNTING RELOAD VALUE)

C/T2

TF2

TR2

EXF2

TH2

(8-bit)

TL2

(8-bit)

RCAP2H

(8-bit)

RCAP2L

(8-bit)

FFh

(8-bit)

FFh

(8-bit)

TOGGLE

(UP COUNTING RELOAD VALUE)

Timer 2

INTERRUPT

CLK PERIPH

T2CON

T2EX:

if DCEN = 1, 1 = UP

if DCEN = 1, 0 = DOWN

if DCEN = 0, up counting

: 6

Cl ock Ou tFreque ncy–

CL KPE RIP H

4 65536 R CAP2H– RCAP 2L⁄( )×

-----------------------------------------------------------------------------------------

AT89C5131A-L

Programmable Clock Output

In the Clock-out mode, Timer 2 operates as a 50%-duty-cycle, programmable clock generator (See Figure 27). The input clock increments TL2 at frequency F timer repeatedly counts to overflow from a loaded value. At overflow, the contents of RCAP2H and RCAP2L registers are loaded into TH2 and TL2. In this mode, Timer 2 overflows do not generate interrupts. The following formula gives the Clock-out frequency as a function of the system oscillator frequency and the value in the RCAP2H and RCAP2L registers

For a 16 MHz system clock, Timer 2 has a programmable frequency range of 61 Hz (F

CLK PERIPH

T2 pin (P1.0).

Timer 2 is programmed for the Clock-out mode as follows:

16)

to 4 MHz (F

• Set T2OE bit in T2MOD register.

• Clear C/T2 bit in T2CON register.

• Determine the 16-bit reload value from the formula and enter it in RCAP2H/RCAP2L registers.

• Enter a 16-bit initial value in timer registers TH2/TL2. It can be the same as the reload value or a different one depending on the application.

• To start the timer, set TR2 run control bit in T2CON register.

CLK PERIPH

/4). The generated clock signal is brought out to

CLK PERIPH

/2. The

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AT89C5131A-L

It is possible to use Timer 2 as a baud rate generator and a clock generator simulta-

: 6

EXF2

TR2

OVERFLOW

T2EX

TH2

(8-bit)

TL2

(8-bit)

Timer 2

RCAP2H

(8-bit)

RCAP2L

(8-bit)

T2OE

CLK PERIPH

T2CON

T2MOD

INTERRUPT

Q D

Toggle

EXEN2

ne ously . For t his c onfigurat ion, t he bau d rat es and clock frequ enci es are not independent since both functions use the values in the RCAP2H and RCAP2L registers.

Figure 27. Clock-out Mode C/T2 = 0

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Table 46. T2CON Register

T2CON - Timer 2 Control Register (C8h)

7 6 5 4 3 2 1 0

TF2 EXF2 RCLK TCLK EXEN2 TR2 C/T2# CP/RL2#

Bit

Number

7 TF2

6 EXF2

5 RCLK

4 TCLK

3 EXEN2

2 TR2

Bit

Mnemonic Description

Timer 2 overflow Flag

Must be cleared by software. Set by hardware on Timer 2 overflow, if RCLK = 0 and TCLK = 0.

Timer 2 External Flag

Set when a capture or a reload is caused by a negative transition on T2EX pin if EXEN2 = 1. When set, causes the CPU to vector to Timer 2 interrupt routine when Timer 2 interrupt is enabled. Must be cleared by software. EXF2 doesn’t cause an interrupt in Up/down counter mode (DCEN = 1).

Receive Clock bit

Cleared to use Timer 1 overflow as receive clock for serial port in mode 1 or 3. Set to use Timer 2 overflow as receive clock for serial port in mode 1 or 3.

Transmit Clock bit

Cleared to use Timer 1 overflow as transmit clock for serial port in mode 1 or 3. Set to use Timer 2 overflow as transmit clock for serial port in mode 1 or 3.

Timer 2 External Enable bit

Cleared to ignore events on T2EX pin for Timer 2 operation. Set to cause a capture or reload when a negative transition on T2EX pin is detected, if Timer 2 is not used to clock the serial port.

Timer 2 Run control bit

Cleared to turn off Timer 2. Set to turn on Timer 2.

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Timer/Counter 2 select bit

1 C/T2#

0 CP/RL2#

Cleared for timer operation (input from internal clock system: F Set for counter operation (input from T2 input pin, falling edge trigger). Must be 0 for clock out mode.

Timer 2 Capture/Reload bit

If RCLK = 1 or TCLK = 1, CP/RL2# is ignored and timer is forced to Auto-reload on Timer 2 overflow. Cleared to Auto-reload on Timer 2 overflows or negative transitions on T2EX pin if EXEN2 = 1. Set to capture on negative transitions on T2EX pin if EXEN2 = 1.

Reset Value = 0000 0000b Bit addressable

CLK PERIPH

AT89C5131A-L

Table 47. T2MOD Register

T2MOD - Timer 2 Mode Control Register (C9h)

7 6 5 4 3 2 1 0

- - - - - - T2OE DCEN

Bit

Number

7 -

6 -

5 -

4 -

3 -

2 -

1 T2OE

0 DCEN

Bit

Mnemonic Description

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Timer 2 Output Enable bit

Cleared to program P1.0/T2 as clock input or I/O port. Set to program P1.0/T2 as clock output.

Down Counter Enable bit

Cleared to disable Timer 2 as up/down counter. Set to enable Timer 2 as up/down counter.

Reset Value = XXXX XX00b Not bit addressable

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AT89C5131A-L

Programmable Counter Array (PCA)

The PCA provides more timing capabilities with less CPU intervention than the standard timer/counters. Its advantages include reduced software overhead and improved accuracy. The PCA consists of a dedicated timer/counter which serves as the time base for an array of five compare/capture modules. Its clock input can be programmed to count any one of the following signals:

• Peripheral clock frequency (F

CLK PERIPH

) ÷ 6

) ÷ 2

• Timer 0 overflow

• External input on ECI (P1.2)

Each compare/capture modules can be programmed in any one of the following modes:

• rising and/or falling edge capture,

• software timer

• high-speed output, or

• pulse width modulator

Module 4 can also be programmed as a watchdog timer (see Section "PCA Watchdog Timer", page 65).

When the compare/capture modules are programmed in the capture mode, software timer, or high speed output mode, an interrupt can be generated when the module executes its function. All five modules plus the PCA timer overflow share one interrupt vector.

The PCA timer/counter and compare/capture modules share Port 1 for external I/O. These pins are listed below. If the port pin is not used for the PCA, it can still be used for standard I/O.

PCA Component External I/O Pin

16-bit Counter P1.2/ECI

16-bit Module 0 P1.3/CEX0

16-bit Module 1 P1.4/CEX1

16-bit Module 2 P1.5/CEX2

16-bit Module 3 P1.6/CEX3

16-bit Module 4 P1.7/CEX4

The PCA timer is a common time base for all five modules (see Figure 28). The timer count source is determined from the CPS1 and CPS0 bits in the CMOD register (Table 48) and can be programmed to run at:

• 1/6 the

• 1/2 the

peripheral clock frequency (F peripheral clock frequency (F

CLK PERIPH

)

• The Timer 0 overflow

• The input on the ECI pin (P1.2)

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Figure 28. PCA Timer/Counter

CIDL CPS1 CPS0 ECF

CH CL

16 Bit Up Counter

To PCA modules

CLK PERIPH

T0 OVF

P1.2

Idle

CMOD 0xD9

WDTE

CF CR

CCON 0xD8

CCF4 CCF3 CCF2 CCF1 CCF0

overflow

Table 48. CMOD Register CMOD - PCA Counter Mode Register (D9h)

7 6 5 4 3 2 1 0

CIDL WDTE - - - CPS1 CPS0 ECF

Bit

Number

Bit

Mnemonic Description

Counter Idle Control

7 CIDL

Cleared to program the PCA Counter to continue functioning during idle Mode.

Set to program PCA to be gated off during idle.

Watchdog Timer Enable

6 WDTE

Cleared to disable Watchdog Timer function on PCA Module 4.

Set to enable Watchdog Timer function on PCA Module 4.

5 -

4 -

3 -

2 CPS1

1 CPS0

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

PCA Count Pulse Select

CPS1CPS0 Selected PCA input 0 0 Internal clock f

0 1 Internal clock f 1 0 Timer 0 Overflow 1 1 External clock at ECI/P1.2 pin (max rate = f

PCA Enable Counter Overflow Interrupt

0 ECF

Cleared to disable CF bit in CCON to inhibit an interrupt. Set to enable CF bit in CCON to generate an interrupt.

Reset Value = 00XX X000b Not bit addressable

CLK PERIPH

/ 4)

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The CMOD regis ter includes three additional bits associated with the PCA (See Figure 28 and Table 48).

• The CIDL bit allows the PCA to stop during idle mode.

• The WDTE bit enables or disables the watchdog function on module 4.

• The ECF bit when set causes an interrupt and the PCA overflow flag CF (in the CCON SFR) to be set when the PCA timer overflows.

The CCON register contains the run control bit for the PCA and the flags for the PCA timer (CF) and each module (see Table 49).

• Bit CR (CCON.6) must be set by software to run the PCA. The PCA is shut off by clearing this bit.

• Bit CF: The CF bit (CCON.7) is set when the PCA counter overflows and an interrupt will be generated if the ECF bit in the CMOD register is set. The CF bit can only be cleared by software.

• Bits 0 through 4 are the flags for the modules (bit 0 for module 0, bit 1 for module 1, etc.) and are set by hardware when either a match or a capture occurs. These flags can only be cleared by software.

Table 49. CCON Register CCON - PCA Counter Control Register (D8h)

7 6 5 4 3 2 1 0

CF CR

Bit

Number

Mnemonic Description

7 CF

6 CR

5 –

4 CCF4

3 CCF3

2 CCF2

1 CCF1

0 CCF0

Bit

–

PCA Counter Overflow flag

Set by hardware when the counter rolls over. CF flags an interrupt if bit ECF in CMOD is set. CF may be set by either hardware or software but can only be cleared by software.

PCA Counter Run control bit

Must be cleared by software to turn the PCA counter off. Set by software to turn the PCA counter on.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

PCA Module 4 interrupt flag

Must be cleared by software. Set by hardware when a match or capture occurs.

PCA Module 3 interrupt flag

Must be cleared by software. Set by hardware when a match or capture occurs.

PCA Module 2 interrupt flag

Must be cleared by software. Set by hardware when a match or capture occurs.

PCA Module 1 Interrupt Flag

Must be cleared by software. Set by hardware when a match or capture occurs.

PCA Module 0 Interrupt Flag

Must be cleared by software. Set by hardware when a match or capture occurs.

CCF4 CCF3 CCF2 CCF1 CCF0

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Reset Value = 000X 0000b Not bit addressable

AT89C5131A-L

Figure 29. PCA Interrupt System

CF CR

CCON

0xD8

CCF4 CCF3 CCF2 CCF1 CCF0

Module 4

Module 3

Module 2

Module 1

Module 0

ECF

PCA Timer/Counter

ECCFn

CCAPMn.0CMOD.0

IE.6 IE.7

To Interrupt

priority decoder

EC EA

The watchdog timer function is implemented in module 4 (See Figure 31).

The PCA interrupt system is shown in Figure 29.

PCA Modules: each one of the five compare/capture modules has six possible functions. It can perform:

• 16-bit capture, positive-edge triggered

• 16-bit capture, negative-edge triggered

• 16-bit capture, both positive and negative-edge triggered

• 16-bit Software Timer

• 16-bit High-speed Output

• 8-bit Pulse Width Modulator

In addition, module 4 can be used as a Watchdog Timer.

Each module in the PCA has a special function register associated with it. These registers are: CCAPM0 for module 0, CCAPM1 for module 1, etc. (see Table 50). The registers contain the bits that control the mode that each module will operate in.

• The ECCF bit (CCAPMn.0 where n = 0, 1, 2, 3, or 4 depending on the module) enables the CCF flag in the CCON SFR to generate an interrupt when a match or compare occurs in the associated module.

• PWM (CCAPMn.1) enables the pulse width modulation mode.

• The TOG bit (CCAPMn.2) when set causes the CEX output associated with the module to toggle when there is a match between the PCA counter and the module's capture/compare register.

• The match bit MAT (CCAPMn.3) when set will cause the CCFn bit in the CCON register to be set when there is a match between the PCA counter and the module's capture/compare register.

• The next two bits CAPN (CCAPMn.4) and CAPP (CCAPMn.5) determine the edge that a capture input will be active on. The CAPN bit enables the negative edge, and

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AT89C5131A-L

the CAPP bit enables the positive edge. If both bits are set both edges will be enabled and a capture will occur for either transition.

• The last bit in the register ECOM (CCAPMn.6) when set enables the comparator function.

Table 51 shows the CCAPMn settings for the various PCA functions.

Table 50. CCAPMn Registers (n = 0-4)

CCAPM0 - PCA Module 0 Compare/Capture Control Register (0DAh) CCAPM1 - PCA Module 1 Compare/Capture Control Register (0DBh) CCAPM2 - PCA Module 2 Compare/Capture Control Register (0DCh) CCAPM3 - PCA Module 3 Compare/Capture Control Register (0DDh) CCAPM4 - PCA Module 4 Compare/Capture Control Register (0DEh)

7 6 5 4 3 2 1 0

- ECOMn CAPPn CAPNn MATn TOGn PWMn ECCFn

Bit

Number

7 -

6 ECOMn

5 CAPPn

4 CAPNn

3 MATn

2 TOGn

1 PWMn

Bit

Mnemonic Description

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Enable Comparator

Cleared to disable the comparator function.

Set to enable the comparator function.

Capture Positive

Cleared to disable positive edge capture. Set to enable positive edge capture.

Capture Negative

Cleared to disable negative edge capture. Set to enable negative edge capture.

Match

When MATn = 1, a match of the PCA counter with this module's compare/capture register causes the

CCFn bit in CCON to be set, flagging an interrupt.

Toggle

When TOGn = 1, a match of the PCA counter with this module's compare/capture register causes the CEXn pin to toggle.

Pulse Width Modulation Mode

Cleared to disable the CEXn pin to be used as a pulse width modulated output.

Set to enable the CEXn pin to be used as a pulse width modulated output.

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Enable CCF Interrupt

Cleared to disable compare/capture flag CCFn in the CCON register to

0 ECCFn

generate an interrupt.

Set to enable compare/capture flag CCFn in the CCON register to generate an interrupt.

Reset Value = X000 0000b Not bit addressable

AT89C5131A-L

Table 51. PCA Module Modes (CCAPMn Registers)

PWMmECCF

ECOMn CAPPn CAPNn MATn TOGn

0 0 0 0 0 0 0 No Operation

n Module Function

X 1 0 0 0 0 X

X 0 1 0 0 0 X

X 1 1 0 0 0 X

1 0 0 1 0 0 X

1 0 0 1 1 0 X 16-bit High Speed Output

1 0 0 0 0 1 0 8-bit PWM

1 0 0 1 X 0 X

16-bit capture by a positiveedge trigger on CEXn

16-bit capture by a negative trigger on CEXn

16-bit capture by a transition on CEXn

16-bit Software Timer/Compare mode.

Watchdog Timer (module 4 only)

There are two additional registers associated with each of the PCA modules. They are CCAPnH and CCAPnL and these are the registers that store the 16-bit count when a capture occurs or a compare should occur. When a module is used in the PWM mode these registers are used to control the duty cycle of the output (see Table 52 and Table 53)

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Table 52. CCAPnH Registers (n = 0-4)

CCAP0H - PCA Module 0 Compare/Capture Control Register High (0FAh) CCAP1H - PCA Module 1 Compare/Capture Control Register High (0FBh) CCAP2H - PCA Module 2 Compare/Capture Control Register High (0FCh) CCAP3H - PCA Module 3 Compare/Capture Control Register High (0FDh) CCAP4H - PCA Module 4 Compare/Capture Control Register High (0FEh)

7 6 5 4 3 2 1 0

- - - - - - - -

Bit

Number

7 - 0 -

Bit

Mnemonic Description

PCA Module n Compare/Capture Control

CCAPnH Value

Reset Value = XXXX XXXXb Not bit addressable

Table 53. CCAPnL Registers (n = 0-4)

CCAP0L - PCA Module 0 Compare/Capture Control Register Low (0EAh) CCAP1L - PCA Module 1 Compare/Capture Control Register Low (0EBh) CCAP2L - PCA Module 2 Compare/Capture Control Register Low (0ECh) CCAP3L - PCA Module 3 Compare/Capture Control Register Low (0EDh) CCAP4L - PCA Module 4 Compare/Capture Control Register Low (0EEh)

7 6 5 4 3 2 1 0

- - - - - - - -

Bit

Number

7 - 0 -

Bit

Mnemonic Description

PCA Module n Compare/Capture Control

CCAPnL Value

Reset Value = XXXX XXXXb Not bit addressable

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Table 54. CH Register

CH - PCA Counter Register High (0F9h)

7 6 5 4 3 2 1 0

- - - - - - - -

Bit

Number

7 - 0 -

Bit

Mnemonic Description

PCA counter

CH Value

Reset Value = 0000 0000b Not bit addressable

AT89C5131A-L

Table 55. CL Register

CF CR

CCON 0xD8

CH CL

CCAPnH CCAPnL

CCF4 CCF3 CCF2 CCF1 CCF0

PCA IT

PCA Counter/Timer

ECOMn

CCAPMn, n = 0 to 4 0xDA to 0xDE

CAPNn MATn TOGn PWMn ECCFnCAPPn

Cex.n

Capture

CL - PCA Counter Register Low (0E9h)

7 6 5 4 3 2 1 0

- - - - - - - -

PCA Capture Mode

Figure 30. PCA Capture Mode

Bit

Number

7 - 0 -

Bit

Mnemonic Description

PCA Counter

CL Value

Reset Value = 0000 0000b Not bit addressable

To use one of the PCA modules in the capture mode either one or both of the CCAPM bits CAPN and CAPP for that module must be set. The external CEX input for the module (on port 1) is sampled for a transition. When a valid transition occurs the PCA hardware loads the value of the PCA counter registers (CH and CL) into the module's capture registers (CCAPnL and CCAPnH). If the CCFn bit for the module in the CCON SFR and the ECCFn bit in the CCAPMn SFR are set then an interrupt will be generated (see Figure 30).

16-bit Software Timer/Compare Mode

The PCA modules can be used as software timers by setting both the ECOM and MAT bits in the modules CCAPMn register. The PCA timer will be compared to the module's capture registers and when a match occurs an interrupt will occur if the CCFn (CCON SFR) and the ECCFn (CCAPMn SFR) bits for the module are both set (see Figure 31).

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Figure 31. PCA Compare Mode and PCA Watchdog Timer

CH CL

CCAPnH CCAPnL

ECOMn

CCAPMn, n = 0 to 4

0xDA to 0xDE

CAPNn MATn TOGn PWMn ECCFnCAPPn

16-bit Comparator

Match

CCON

0xD8

PCA IT

Enable

PCA Counter/Timer

RESET

(1)

CIDL CPS1 CPS0 ECF

CMOD

0xD9

WDTE

Reset

Write to

CCAPnL

Write to

CCAPnH

CF CCF2 CCF1 CCF0

CCF3

CCF4

1 0

AT89C5131A-L

High Speed Output Mode

Note: 1. Only for Module 4

Before enabling ECOM bit, CCAPnL and CCAPnH should be set with a non zero value, otherwise an unwanted match could happen. Writing to CCAPnH will set the ECOM bit.

Once ECOM set, writing CCAPnL will clear ECOM so that an unwanted match doesn’t occur while modifying the compare value. Writing to CCAPnH will set ECOM. For this reason, user software should write CCAPnL first, and then CCAPnH. Of course, the ECOM bit can still be controlled by accessing to CCAPMn register.

In this mode, the CEX output (on port 1) associated with the PCA module will toggle each time a match occurs between the PCA counter and the module's capture registers. To activate this mode the TOG, MAT, and ECOM bits in the module's CCAPMn SFR must be set (see Figure 32).

A prior write must be done to CCAPnL and CCAPnH before writing the ECOMn bit.

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AT89C5131A-L

Figure 32. PCA High-speed Output Mode

CH CL

CCAPnH CCAPnL

ECOMn

CCAPMn, n = 0 to 4

0xDA to 0xDE

CAPNn MATn TOGn PWMn ECCFnCAPPn

16-bit Comparator

Match

CF CR

CCON

0xD8

CCF4 CCF3 CCF2 CCF1 CCF0

PCA IT

Enable

CEXn

PCA counter/timer

Write to

CCAPnH

Reset

Write to

CCAPnL

Before enabling ECOM bit, CCAPnL and CCAPnH should be set with a non zero value, otherwise an unwanted match could happen.

Pulse Width Modulator Mode

All of the PCA modules can be used as PWM outputs. Figure 33 shows the PWM function. The frequency of the output depends on the source for the PCA timer. All of the modules will have the same frequency of output because they all share the PCA timer. The duty cycle of each module is independently variable using the module's capture register CCAPLn. When the value of the PCA CL SFR is less than the value in the module's CCAPLn SFR the output will be low, when it is equal to or greater than the output will be high. When CL overflows from FF to 00, CCAPLn is reloaded with the value in CCAPHn. This allows updating the PWM without glitches. The PWM and ECOM bits in the module's CCAPMn register must be set to enable the PWM mode.

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Figure 33. PCA PWM Mode

CCAPnH

CCAPnL

ECOMn

CCAPMn, n = 0 to 4

0xDA to 0xDE

CAPNn MATn TOGn PWMn ECCFnCAPPn

8-bit Comparator

CEXn

“0”

“1”

≥

Enable

PCA Counter/Timer

Overflow

AT89C5131A-L

PCA Watchdog Timer

An on-board watchdog timer is available with the PCA to improve the reliability of the system without increasing chip count. Watchdog timers are useful for systems that are susceptible to noise, power glitches, or electrostatic discharge. Module 4 is the only PCA module that can be programmed as a watchdog. However, this module can still be used for other modes if the watchdog is not needed. Figure 31 shows a diagram of how the watchdog works. The user pre-loads a 16-bit value in the compare registers. Just like the other compare modes, this 16-bit value is compared to the PCA timer value. If a match is allowed to occur, an internal reset will be generated. This will not cause the RST pin to be driven low.

In order to hold off the reset, the user has three options:

1. Periodically change the compare value so it will never match the PCA timer

2. Periodically change the PCA timer value so it will never match the compare values, or

3. Disable the watchdog by clearing the WDTE bit before a match occurs and then re-enable it

The first two options are more reliable because the watchdog timer is never disabled as in option #3. If the program counter ever goes astray, a match will eventually occur and cause an internal reset. The second option is also not recommended if other PCA modules are being used. Remember, the PCA timer is the time base for all modules; changing the time base for other modules would not be a good idea. Thus, in most applications the first solution is the best option.

This watchdog timer won’t generate a reset out on the reset pin.

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AT89C5131A-L

Serial I/O Port

RITIRB8TB8RENSM2SM1SM0/FE

IDLPDGF0GF1POF-SMOD0SMOD1

To UART Framing Error Control

SM0 to UART Mode Control (SMOD0 = 0)

Set FE Bit if Stop Bit is 0 (framing error) (SMOD0 = 1)

SCON (98h)

PCON (87h)

Data Byte

SMOD0 = X

Stop

Bit

Start

Bit

RXD

D7D6D5D4D3D2D1D0

SMOD0 = 1

The serial I/O port in the AT89C5131A-L is compatible with the serial I/O port in the 80C52. It provides both synchronous and asynchronous communication modes. It operates as an Universal Asynchronous Receiver and Transmitter (UART) in three full-duplex modes (modes 1, 2 and 3). Asynchronous transmission and reception can occur simultaneously and at different baud rates.

Serial I/O port includes the following enhancements:

• Framing error detection

• Automatic address recognition

Framing Error Detection

Framing bit error detection is provided for the three asynchronous modes (modes 1, 2 and 3). To enable the framing bit error detection feature, set SMOD0 bit in PCON register (see Figure 34).

Figure 34. Framing Error Block Diagram

When this feature is enabled, the receiver checks each incoming data frame for a valid stop bit. An invalid stop bit may result from noise on the serial lines or from simultaneous transmission by two CPUs. If a valid stop bit is not found, the Framing Error bit (FE) in SCON register (See Table 56) bit is set. Software may examine FE bit after each reception to check for data errors. Once set, only software or a reset can clear FE bit. Subsequently received frames with valid stop bits cannot clear FE bit. When FE feature is enabled, RI rises on stop bit instead of the last data bit (See Figure 35 and Figure 36).

Figure 35. UART Timings in Mode 1

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Figure 36. UART Timings in Modes 2 and 3

SMOD0 = 0

Data Byte Ninth

Bit

Stop

Bit

Start

Bit

RXD

D8D7D6D5D4D3D2D1D0

SMOD0 = 1

AT89C5131A-L

Automatic Address Recognition

The automatic address recognition feature is enabled when the multiprocessor communication feature is enabled (SM2 bit in SCON register is set).

Implemented in hardware, automatic address recognition enhances the multiprocessor communication feature by allowing the serial port to examine the address of each incoming command frame. Only when the serial port recognizes its own address, the receiver sets RI bit in SCON register to generate an interrupt. This ensures that the CPU is not interrupted by command frames addressed to other devices.

If desired, you may enable the automatic address recognition feature in mode 1. In this configuration, the stop bit takes the place of the ninth data bit. Bit RI is set only when the received command frame address matches the device’s address and is terminated by a valid stop bit.

To support automatic address recognition, a device is identified by a given address and a broadcast address.

Note: The multiprocessor communication and automatic address recognition features cannot

be enabled in mode 0 (i.e., setting SM2 bit in SCON register in mode 0 has no effect).

Given Address Each device has an individual address that is specified in SADDR register; the SADEN

register is a mask byte that contains don’t care bits (defined by zeros) to form the device’s given address. The don’t care bits provide the flexibility to address one or more slaves at a time. The following example illustrates how a given address is formed.

To address a device by its individual address, the SADEN mask byte must be 1111 1111b. For example:

SADDR0101 0110b SADEN1111 1100b

Given0101 01XXb

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The following is an example of how to use given addresses to address different slaves:

Slave A:SADDR1111 0001b

SADEN1111 1010b

Given1111 0X0Xb

Slave B:SADDR1111 0011b

SADEN1111 1001b

Given1111 0XX1b

Slave C:SADDR1111 0011b

SADEN1111 1101b

Given1111 00X1b

AT89C5131A-L

The SADEN byte is selected so that each slave may be addressed separately.

For slave A, bit 0 (the LSB) is a don’t care bit; for slaves B and C, bit 0 is a 1. To communicate with slave A only, the master must send an address where bit 0 is clear (e.g. 1111 0000b).

For slave A, bit 1 is a 1; for slaves B and C, bit 1 is a don’t care bit. To communicate with slaves B and C, but not slave A, the master must send an address with bits 0 and 1 both set (e.g. 1111 0011b).

To communicate with slaves A, B and C, the master must send an address with bit 0 set, bit 1 clear, and bit 2 clear (e.g. 1111 0001b).

Broadcast Address A broadcast address is formed from the logical OR of the SADDR and SADEN registers

with zeros defined as don’t care bits, e.g.:

SADDR0101 0110b SADEN1111 1100b

Broadcast = SADDR OR SADEN1111 111Xb

The use of don’t care bits provides flexibility in defining the broadcast address, in most applications, a broadcast address is FFh. The following is an example of using broadcast addresses:

Slave A:SADDR1111 0001b

SADEN1111 1010b

Broadcast1111 1X11b,

Slave B:SADDR1111 0011b

SADEN1111 1001b

Broadcast1111 1X11B,

Slave C:SADDR = 1111 0011b

SADEN1111 1101b

Broadcast1111 1111b

For slaves A and B, bit 2 is a don’t care bit; for slave C, bit 2 is set. To communicate with all of the slaves, the master must send an address FFh. To communicate with slaves A and B, but not slave C, the master can send and address FBh.

Reset Addresses On reset, the SADDR and SADEN registers are initialized to 00h, i.e. the given and

broadcast addresses are XXXX XXXXb (all don’t care bits). This ensures that the serial port will reply to any address, and so, that it is backwards compatible with the 80C51 microcontrollers that do not support automatic address recognition.

SADEN - Slave Address Mask Register (B9h)

7 6 5 4 3 2 1 0

Reset Value = 0000 0000b Not bit addressable

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AT89C5131A-L

RCLK

/ 16

RBCK

INT_BRG

TIMER1

TIMER2

INT_BRG

TIMER1

TIMER2

TIMER_BRG_RX

Rx Clock

/ 16

TIMER_BRG_TX

Tx Clock

TBCK

TCLK

SADDR - Slave Address Register (A9h)

7 6 5 4 3 2 1 0

Reset Value = 0000 0000b Not bit addressable

Baud Rate Selection for UART for Mode 1 and 3

Baud Rate Selection Table for UART

The Baud Rate Generator for transmit and receive clocks can be selected separately via the T2CON and BDRCON registers.

Figure 37. Baud Rate Selection

TCLK

(T2CON)

0 0 0 0 Timer 1 Timer 1

RCLK

(T2CON)

TBCK

(BDRCON)

RBCK

(BDRCON)

Clock Source

UART Tx

Clock Source

UART Rx

Internal Baud Rate Generator (BRG)

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1 0 0 0 Timer 2 Timer 1

0 1 0 0 Timer 1 Timer 2

1 1 0 0 Timer 2 Timer 2

X 0 1 0 INT_BRG Timer 1

X 1 1 0 INT_BRG Timer 2

0 X 0 1 Timer 1 INT_BRG

1 X 0 1 Timer 2 INT_BRG

X X 1 1 INT_BRG INT_BRG

When the internal Baud Rate Generator is used, the Baud Rates are determined by the BRG overflow depending on the BRL reload value, the value of SPD bit (Speed Mode) in BDRCON register and the value of the SMOD1 bit in PCON register.

AT89C5131A-L

Figure 38. Internal Baud Rate

BRG

BRL

INT_BRG

SPD

BRR

SMOD1

auto reload counter

overflow

Peripheral Clock

Baud_Rate =

SMOD1

x FCLK PERIPH

2 x 6

(1-SPD)

x 16 x [256 - (BRL)]

(BRL) = 256

SMOD1

x F

CLK PERIPH

2 x 6

(1-SPD)

x 16 x Baud_Rate

• The baud rate for UART is token by formula:

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AT89C5131A-L

Table 56. SCON Register – SCON Serial Control Register (98h)

7 6 5 4 3 2 1 0

FE/SM0 SM1 SM2 REN TB8 RB8 TI RI

Bit

Number

6 SM1

5 SM2

4 REN

3 TB8

Bit

Mnemonic Description

Framing Error bit (SMOD0 = 1

SM0

Clear to reset the error state, not cleared by a valid stop bit. Set by hardware when an invalid stop bit is detected.

SMOD0 must be set to enable access to the FE bit

Serial port Mode bit 0

Refer to SM1 for serial port mode selection.

SMOD0 must be cleared to enable access to the SM0 bit

Serial port Mode bit 1

SM0SM1ModeDescriptionBaud Rate 0 0 0 Shift RegisterF 0 1 1 8-bit UARTVariable 1 0 2 9-bit UARTF

1 1 3 9-bit UART Variable

Serial port Mode 2 bit/Multiprocessor Communication Enable bit

Clear to disable multiprocessor communication feature. Set to enable multiprocessor communication feature in mode 2 and 3, and eventually mode 1. This bit should be cleared in mode 0.

Reception Enable bit

Clear to disable serial reception. Set to enable serial reception.

Transmitter Bit 8/Ninth bit to Transmit in Modes 2 and 3

Clear to transmit a logic 0 in the 9th bit. Set to transmit a logic 1 in the 9th bit.

CPU PERIPH

CPU PERIPH/

)

32 or/16

Receiver Bit 8/Ninth bit received in modes 2 and 3

2 RB8

1 TI

0 RI

Cleared by hardware if 9th bit received is a logic 0. Set by hardware if 9th bit received is a logic 1.

In mode 1, if SM2 = 0, RB8 is the received stop bit. In mode 0 RB8 is not used.

Transmit Interrupt flag

Clear to acknowledge interrupt. Set by hardware at the end of the 8th bit time in mode 0 or at the beginning of the stop bit in the other modes.

Receive Interrupt flag

Clear to acknowledge interrupt. Set by hardware at the end of the 8th bit time in mode 0, see Figure 35. and Figure 36. in the other modes.

Reset Value = 0000 0000b Bit addressable

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AT89C5131A-L

Example of computed value when X2 = 1, SMOD1 = 1, SPD = 1

= 16.384 MHz F

Baud Rates

115200 247 1.23 243 0.16

57600 238 1.23 230 0.16

38400 229 1.23 217 0.16

28800 220 1.23 204 0.16

19200 203 0.63 178 0.16

9600 149 0.31 100 0.16

4800 43 1.23 - -

OSC

BRL Error (%) BRL Error (%)

OSC

Example of computed value when X2 = 0, SMOD1 = 0, SPD = 0

= 16.384 MHz F

OSC

Baud Rates

4800 247 1.23 243 0.16

2400 238 1.23 230 0.16

1200 220 1.23 202 3.55

BRL Error (%) BRL Error (%)

OSC

= 24 MHz

UART Registers

600 185 0.16 152 0.16

The baud rate generator can be used for mode 1 or 3 (refer to Figure 37.), but also for mode 0 for UART, thanks to the bit SRC located in BDRCON register (Table 59.)

SADEN - Slave Address Mask Register for UART (B9h)

7 6 5 4 3 2 1 0

– – – – – – – –

Reset Value = 0000 0000b

SADDR - Slave Address Register for UART (A9h)

7 6 5 4 3 2 1 0

– – – – – – – –

Reset Value = 0000 0000b

SBUF - Serial Buffer Register for UART (99h)

7 6 5 4 3 2 1 0

– – – – – – – –

Reset Value = XXXX XXXXb

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AT89C5131A-L

BRL - Baud Rate Reload Register for the internal baud rate generator, UART (9Ah)

7 6 5 4 3 2 1 0

– – – – – – – –

Reset Value = 0000 0000b

Table 57. T2CON Register

T2CON - Timer 2 Control Register (C8h)

7 6 5 4 3 2 1 0

TF2 EXF2 RCLK TCLK EXEN2 TR2 C/T2# CP/RL2#

Bit

Number

7 TF2

6 EXF2

5 RCLK

4 TCLK

3 EXEN2

2 TR2

Bit

Mnemonic Description

Timer 2 overflow Flag

Must be cleared by software. Set by hardware on Timer 2 overflow, if RCLK = 0 and TCLK = 0.

Timer 2 External Flag

Receive Clock bit for UART

Cleared to use Timer 1 overflow as receive clock for serial port in mode 1 or 3. Set to use Timer 2 overflow as receive clock for serial port in mode 1 or 3.

Transmit Clock bit for UART

Cleared to use Timer 1 overflow as transmit clock for serial port in mode 1 or 3. Set to use Timer 2 overflow as transmit clock for serial port in mode 1 or 3.

Timer 2 External Enable bit

Cleared to ignore events on T2EX pin for Timer 2 operation. Set to cause a capture or reload when a negative transition on T2EX pin is detected, if Timer 2 is not used to clock the serial port.

Timer 2 Run control bit

Cleared to turn off Timer 2. Set to turn on Timer 2.

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Timer/Counter 2 select bit

1 C/T2#

0 CP/RL2#

Cleared for timer operation (input from internal clock system: F Set for counter operation (input from T2 input pin, falling edge trigger). Must be 0 for clock out mode.

Timer 2 Capture/Reload bit

Reset Value = 0000 0000b Bit addressable

CLK PERIPH

AT89C5131A-L

Table 58. PCON Register

PCON - Power Control Register (87h)

7 6 5 4 3 2 1 0

SMOD1 SMOD0 - POF GF1 GF0 PD IDL

Bit

Number

7 SMOD1

6 SMOD0

5 -

4 POF

3 GF1

2 GF0

1 PD

0 IDL

Bit

Mnemonic Description

Serial port Mode bit 1 for UART

Set to select double baud rate in mode 1, 2 or 3.

Serial port Mode bit 0 for UART

Cleared to select SM0 bit in SCON register. Set to select FE bit in SCON register.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Power-Off Flag

Cleared to recognize next reset type. Set by hardware when VCC rises from 0 to its nominal voltage. Can also be set by software.

General-purpose Flag

Cleared by user for general-purpose usage. Set by user for general-purpose usage.

General-purpose Flag

Cleared by user for general-purpose usage. Set by user for general-purpose usage.

Power-down Mode Bit

Cleared by hardware when reset occurs. Set to enter power-down mode.

Idle Mode Bit

Cleared by hardware when interrupt or reset occurs. Set to enter idle mode.

Reset Value = 00X1 0000b Not bit addressable

Power-off flag reset value will be 1 only after a power on (cold reset). A warm reset doesn’t affect the value of this bit.

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AT89C5131A-L

Table 59. BDRCON Register

BDRCON - Baud Rate Control Register (9Bh)

7 6 5 4 3 2 1 0

- - - BRR TBCK RBCK SPD SRC

Bit

Number

7 -

6 -

5 -

4 BRR

3 TBCK

2 RBCK

1 SPD

0 SRC

Bit

Mnemonic Description

Reserved

The value read from this bit is indeterminate. Do not set this bit

Reserved

The value read from this bit is indeterminate. Do not set this bit

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Baud Rate Run Control bit

Cleared to stop the internal Baud Rate Generator. Set to start the internal Baud Rate Generator.

Transmission Baud rate Generator Selection bit for UART

Cleared to select Timer 1 or Timer 2 for the Baud Rate Generator. Set to select internal Baud Rate Generator.

Reception Baud Rate Generator Selection bit for UART

Cleared to select Timer 1 or Timer 2 for the Baud Rate Generator. Set to select internal Baud Rate Generator.

Baud Rate Speed Control bit for UART

Cleared to select the SLOW Baud Rate Generator. Set to select the FAST Baud Rate Generator.

Baud Rate Source select bit in Mode 0 for UART

Cleared to select F mode). Set to select the internal Baud Rate Generator for UARTs in mode 0.

/12 as the Baud Rate Generator (F

OSC

CLK PERIPH

/6 in X2

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Reset Value = XXX0 0000b Not bit addressable

AT89C5131A-L

Interrupt System

IE1

High priority interrupt

Interrupt Polling Sequence, Decreasing From

High-to-Low Priority

Low Priority

Interrupt

Global DisableIndividual Enable

EXF2

TF2

TF0

INT0

INT1

TF1

IPH, IPL

IE0

PCA IT

KBD IT

SPI IT

UEPINT

USBINT

TWI IT

IT0

TCON.0

IT1

TCON.2

Overview

Figure 39. Interrupt Control System

The AT89C5131A-L has a total of 11 interrupt vectors: two external interrupts (INT0 and INT1), three timer interrupts (timers 0, 1 and 2), the serial port interrupt, SPI interrupt, Keyboard interrupt, USB interrupt and the PCA global interrupt. These interrupts are shown in Figure 39.

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AT89C5131A-L

Each of the interrupt sources can be individually enabled or disabled by setting or clearing a bit in the Interrupt Enable register (Table 61). This register also contains a global disable bit, which must be cleared to disable all interrupts at once.

Each interrupt source can also be individually programmed to one out of four priority levels by setting or clearing a bit in the Interrupt Priority register (Table 62.) and in the Interrupt Priority High register (Table 63). Table 60. shows the bit values and priority levels associated with each combination.

Registers

The PCA interrupt vector is located at address 0033H, the SPI interrupt vector is located at address 004BH and Keyboard interrupt vector is located at address 003BH. All other vectors addresses are the same as standard C52 devices.

Table 60. Priority Level Bit Values

IPH.x IPL.x Interrupt Level Priority

0 0 0 (Lowest)

0 1 1

1 0 2

1 1 3 (Highest)

A low-priority interrupt can be interrupted by a high priority interrupt, but not by another low-priority interrupt. A high-priority interrupt can’t be interrupted by any other interrupt source.

If two interrupt requests of different priority levels are received simultaneously, the request of higher priority level is serviced. If interrupt requests of the same priority level are received simultaneously, an internal polling sequence determines which request is serviced. Thus within each priority level there is a second priority structure determined by the polling sequence.

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AT89C5131A-L

Table 61. IEN0 Register

IEN0 - Interrupt Enable Register (A8h)

7 6 5 4 3 2 1 0

EA EC ET2 ES ET1 EX1 ET0 EX0

Bit

Number

7 EA

6 EC

5 ET2

4 ES

3 ET1

2 EX1

1 ET0

Bit

Mnemonic Description

Enable All interrupt bit

Cleared to disable all interrupts. Set to enable all interrupts.

PCA interrupt enable bit

Cleared to disable.

Set to enable.

Timer 2 overflow interrupt Enable bit

Cleared to disable Timer 2 overflow interrupt. Set to enable Timer 2 overflow interrupt.

Serial port Enable bit

Cleared to disable serial port interrupt. Set to enable serial port interrupt.

Timer 1 overflow interrupt Enable bit

Cleared to disable Timer 1 overflow interrupt. Set to enable Timer 1 overflow interrupt.

External interrupt 1 Enable bit

Cleared to disable external interrupt 1. Set to enable external interrupt 1.

Timer 0 overflow interrupt Enable bit

Cleared to disable timer 0 overflow interrupt. Set to enable timer 0 overflow interrupt.

0 EX0

External interrupt 0 Enable bit

Cleared to disable external interrupt 0. Set to enable external interrupt 0.

Reset Value = 0000 0000b Bit addressable

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AT89C5131A-L

Table 62. IPL0 Register

IPL0 - Interrupt Priority Register (B8h)

7 6 5 4 3 2 1 0

- PPCL PT2L PSL PT1L PX1L PT0L PX0L

Bit

Number

7 -

6 PPCL

5 PT2L

4 PSL

3 PT1L

2 PX1L

1 PT0L

0 PX0L

Bit

Mnemonic Description

Reserved

The value read from this bit is indeterminate. Do not set this bit.

PCA interrupt Priority bit

Refer to PPCH for priority level.

Timer 2 overflow interrupt Priority bit

Refer to PT2H for priority level.

Serial port Priority bit

Refer to PSH for priority level.

Timer 1 overflow interrupt Priority bit

Refer to PT1H for priority level.

External interrupt 1 Priority bit

Refer to PX1H for priority level.

Timer 0 overflow interrupt Priority bit

Refer to PT0H for priority level.

External interrupt 0 Priority bit

Refer to PX0H for priority level.

Reset Value = X000 0000b Bit addressable

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AT89C5131A-L

Table 63. IPH0 Register

IPH0 - Interrupt Priority High Register (B7h)

7 6 5 4 3 2 1 0

- PPCH PT2H PSH PT1H PX1H PT0H PX0H

Bit

Number

7 -

6 PPCH

5 PT2H

4 PSH

3 PT1H

Bit

Mnemonic Description

Reserved

The value read from this bit is indeterminate. Do not set this bit.

PCA interrupt Priority high bit.

PPCHPPCLPriority Level 0 0Lowest 0 1 1 0 1 1Highest

Timer 2 overflow interrupt Priority High bit

PT2HPT2LPriority Level 0 0Lowest 0 1 1 0 1 1Highest

Serial port Priority High bit

PSHPSLPriority Level 0 0Lowest 0 1 1 0 1 1Highest

Timer 1 overflow interrupt Priority High bit

PT1HPT1LPriority Level 0 0Lowest 0 1 1 0 1 1Highest

External interrupt 1 Priority High bit

PX1HPX1LPriority Level

2 PX1H

1 PT0H

0 PX0H

0 0Lowest 0 1 1 0 1 1Highest

Timer 0 overflow interrupt Priority High bit

PT0HPT0LPriority Level 0 0Lowest 0 1 1 0 1 1Highest

External interrupt 0 Priority High bit

PX0HPX0LPriority Level 0 0Lowest 0 1 1 0 1 1Highest

Reset Value = X000 0000b Not bit addressable

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AT89C5131A-L

Table 64. IEN1 Register

IEN1 - Interrupt Enable Register (B1h)

7 6 5 4 3 2 1 0

- EUSB - - - ESPI ETWI EKB

Bit

Number

7 - Reserved

6 EUSB

5 - Reserved

4 - Reserved

3 - Reserved

2 ESPI

1 ETWI

0 EKB

Bit

Mnemonic Description

USB Interrupt Enable bit

Cleared to disable USB interrupt. Set to enable USB interrupt.

SPI interrupt Enable bit

Cleared to disable SPI interrupt. Set to enable SPI interrupt.

TWI interrupt Enable bit

Cleared to disable TWI interrupt. Set to enable TWI interrupt.

Keyboard interrupt Enable bit

Cleared to disable keyboard interrupt. Set to enable keyboard interrupt.

Reset Value = X0XX X000b Not bit addressable

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AT89C5131A-L

Table 65. IPL1 Register

IPL1 - Interrupt Priority Register (B2h)

7 6 5 4 3 2 1 0

- PUSBL - - - PSPIL PTWIL PKBDL

Bit

Number

7 -

6 PUSBL

5 -

4 -

3 -

2 PSPIL

1 PTWIL

0 PKBL

Bit

Mnemonic Description

Reserved

The value read from this bit is indeterminate. Do not set this bit.

USB Interrupt Priority bit

Refer to PUSBH for priority level.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

SPI Interrupt Priority bit

Refer to PSPIH for priority level.

TWI Interrupt Priority bit

Refer to PTWIH for priority level.

Keyboard Interrupt Priority bit

Refer to PKBH for priority level.

Reset Value = X0XX X000b Not bit addressable

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AT89C5131A-L

Table 66. IPH1 Register

IPH1 - Interrupt Priority High Register (B3h)

7 6 5 4 3 2 1 0

- PUSBH - - - PSPIH PTWIH PKBH

Bit

Number

7 -

6 PUSBH

5 -

4 -

3 -

2 PSPIH

1 PTWIH

Bit

Mnemonic Description

Reserved

The value read from this bit is indeterminate. Do not set this bit.

USB Interrupt Priority High bit

PUSBHPUSBLPriority Level 0 0Lowest 0 1 1 0 1 1Highest

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

SPI Interrupt Priority High bit

PSPIHPSPILPriority Level 0 0Lowest 0 1 1 0 1 1Highest

TWI Interrupt Priority High bit

PTWIHPTWILPriority Level 0 0Lowest 0 1 1 0 1 1Highest

4338F–USB–08/07

Keyboard Interrupt Priority High bit

PKBHPKBLPriority Level

0 PKBH

0 0Lowest 0 1 1 0 1 1Highest

Reset Value = X0XX X000b Not bit addressable

AT89C5131A-L

Interrupt Sources and Vector Addresses

Table 67. Vector Table

Number

0 0 Reset 0000h

1 1 INT0 IE0 0003h

2 2 Timer 0 TF0 000Bh

3 3 INT1 IE1 0013h

4 4 Timer 1 IF1 001Bh

5 6 UART RI+TI 0023h

6 7 Timer 2 TF2+EXF2 002Bh

7 5 PCA CF + CCFn (n = 0-4) 0033h

8 8 Keyboard KBDIT 003Bh

9 9 TWI TWIIT 0043h

10 10 SPI SPIIT 004Bh

11 11 0053h

12 12 005Bh

13 13 0063h

Polling

Priority

Interrupt

Source

Interrupt

Request

Vector

Address

14 14 USB UEPINT + USBINT 006Bh

15 15 0073h

4338F–USB–08/07

Keyboard Interface

P1.0

Keyboard Interface Interrupt Request

KBD

IE1.0

Input Circuitry

P1.1 Input Circuitry

P1.2 Input Circuitry

P1.3 Input Circuitry

P1.4 Input Circuitry

P1.5 Input Circuitry

P1.6 Input Circuitry

P1.7 Input Circuitry

KBDIT

P1:x

KBE.x

KBF.x

KBLS.x

Vcc

Internal Pull-up

AT89C5131A-L

Introduction

The AT89C5131A-L implements a keyboard interface allowing the connection of a 8 x n matrix keyboard. It is based on 8 inputs with programmable interrupt capability on both high or low level. These inputs are available as an alternate function of P1 and allow to exit from idle and power down modes.

Description

The keyboard interface communicates with the C51 core through 3 special function registers: KBLS, the Keyboard Level Selection register (Table 70), KBE, The Keyboard interrupt Enable register (Table 69), and KBF, the Keyboard Flag register (Table 68).

Interrupt The keyboard inputs are considered as 8 independent interrupt sources sharing the

same interrupt vector. An interrupt enable bit (KBD in IE1) allows global enable or disable of the keyboard interrupt (see Figure 40). As detailed in Figure 41 each keyboard input has the capability to detect a programmable level according to KBLS.x bit value. Level detection is then reported in interrupt flags KBF.x that can be masked by software using KBE.x bits.

This structure allow keyboard arrangement from 1 by n to 8 by n matrix and allow usage of P1 inputs for other purpose.

Figure 40. Keyboard Interface Block Diagram

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Figure 41. Keyboard Input Circuitry

AT89C5131A-L

Power Reduction Mode P1 inputs allow exit from idle and power down modes as detailed in section “Power-

down Mode”.

Registers

Table 68. KBF Register

KBF - Keyboard Flag Register (9Eh)

7 6 5 4 3 2 1 0

KBF7 KBF6 KBF5 KBF4 KBF3 KBF2 KBF1 KBF0

Bit

Number

7 KBF7

6 KBF6

5 KBF5

4 KBF4

Bit

Mnemonic Description

Keyboard line 7 flag

Set by hardware when the Port line 7 detects a programmed level. It generates a Keyboard interrupt request if the KBKBIE.7 bit in KBIE register is set. Cleared by hardware when reading KBF SFR by software.

Keyboard line 6 flag

Set by hardware when the Port line 6 detects a programmed level. It generates a Keyboard interrupt request if the KBIE.6 bit in KBIE register is set. Cleared by hardware when reading KBF SFR by software.

Keyboard line 5 flag

Set by hardware when the Port line 5 detects a programmed level. It generates a Keyboard interrupt request if the KBIE.5 bit in KBIE register is set. Cleared by hardware when reading KBF SFR by software.

Keyboard line 4 flag

Set by hardware when the Port line 4 detects a programmed level. It generates a Keyboard interrupt request if the KBIE.4 bit in KBIE register is set. Cleared by hardware when reading KBF SFR by software.

Keyboard line 3 flag

3 KBF3

2 KBF2

1 KBF1

0 KBF0

Set by hardware when the Port line 3 detects a programmed level. It generates a Keyboard interrupt request if the KBIE.3 bit in KBIE register is set. Cleared by hardware when reading KBF SFR by software.

Keyboard line 2 flag

Set by hardware when the Port line 2 detects a programmed level. It generates a Keyboard interrupt request if the KBIE.2 bit in KBIE register is set. Must be cleared by software.

Keyboard line 1 flag

Set by hardware when the Port line 1 detects a programmed level. It generates a Keyboard interrupt request if the KBIE.1 bit in KBIE register is set. Cleared by hardware when reading KBF SFR by software.

Keyboard line 0 flag

Set by hardware when the Port line 0 detects a programmed level. It generates a Keyboard interrupt request if the KBIE.0 bit in KBIE register is set. Cleared by hardware when reading KBF SFR by software.

Reset Value = 0000 0000b

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AT89C5131A-L

Table 69. KBE Register

KBE - Keyboard Input Enable Register (9Dh)

7 6 5 4 3 2 1 0

KBE7 KBE6 KBE5 KBE4 KBE3 KBE2 KBE1 KBE0

Bit

Number

7 KBE7

6 KBE6

5 KBE5

4 KBE4

3 KBE3

2 KBE2

1 KBE1

Bit

Mnemonic Description

Keyboard line 7 Enable bit

Cleared to enable standard I/O pin. Set to enable KBF.7 bit in KBF register to generate an interrupt request.

Keyboard line 6 Enable bit

Cleared to enable standard I/O pin. Set to enable KBF.6 bit in KBF register to generate an interrupt request.

Keyboard line 5 Enable bit

Cleared to enable standard I/O pin. Set to enable KBF.5 bit in KBF register to generate an interrupt request.

Keyboard line 4 Enable bit

Cleared to enable standard I/O pin. Set to enable KBF.4 bit in KBF register to generate an interrupt request.

Keyboard line 3 Enable bit

Cleared to enable standard I/O pin. Set to enable KBF.3 bit in KBF register to generate an interrupt request.

Keyboard line 2 Enable bit

Cleared to enable standard I/O pin. Set to enable KBF.2 bit in KBF register to generate an interrupt request.

Keyboard line 1 Enable bit

Cleared to enable standard I/O pin. Set to enable KBF.1 bit in KBF register to generate an interrupt request.

0 KBE0

Keyboard line 0 Enable bit

Cleared to enable standard I/O pin. Set to enable KBF.0 bit in KBF register to generate an interrupt request.

Reset Value = 0000 0000b

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AT89C5131A-L

Table 70. KBLS Register

KBLS-Keyboard Level Selector Register (9Ch)

7 6 5 4 3 2 1 0

KBLS7 KBLS6 KBLS5 KBLS4 KBLS3 KBLS2 KBLS1 KBLS0

Bit

Number

7 KBLS7

6 KBLS6

5 KBLS5

4 KBLS4

3 KBLS3

2 KBLS2

1 KBLS1

Bit

Mnemonic Description

Keyboard line 7 Level Selection bit

Cleared to enable a low level detection on Port line 7. Set to enable a high level detection on Port line 7.

Keyboard line 6 Level Selection bit

Cleared to enable a low level detection on Port line 6. Set to enable a high level detection on Port line 6.

Keyboard line 5 Level Selection bit

Cleared to enable a low level detection on Port line 5. Set to enable a high level detection on Port line 5.

Keyboard line 4 Level Selection bit

Cleared to enable a low level detection on Port line 4. Set to enable a high level detection on Port line 4.

Keyboard line 3 Level Selection bit

Cleared to enable a low level detection on Port line 3. Set to enable a high level detection on Port line 3.

Keyboard line 2 Level Selection bit

Cleared to enable a low level detection on Port line 2. Set to enable a high level detection on Port line 2.

Keyboard line 1 Level Selection bit

Cleared to enable a low level detection on Port line 1. Set to enable a high level detection on Port line 1.

0 KBLS0

Keyboard line 0 Level Selection bit

Cleared to enable a low level detection on Port line 0. Set to enable a high level detection on Port line 0.

Reset Value = 0000 0000b

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AT89C5131A-L

Programmable LED

AT89C5131A-L have up to 4 programmable LED current sources, configured by the register LEDCON.

Table 71. LEDCON Register

LEDCON (S:F1h) LED Control Register

7 6 5 4 3 2 1 0

LED3 LED2 LED1 LED0

Bit Number

7:6 LED3

5:4 LED2

3:2 LED1

Bit Mnemonic Description

PortLED3Configuration

0 0Standard C51 Port 0 1 2 mA current source when P3.7 is low 1 0 4 mA current source when P3.7 is low 1 1 10 mA current source when P3.7 is low

Port/LED2Configuration

0 0 Standard C51 Port 0 1 2 mA current source when P3.6 is low 1 0 4 mA current source when P3.6 is low 1 1 10 mA current source when P3.6 is low

Port/LED1Configuration

0 0 Standard C51 Port 0 1 2 mA current source when P3.5 is low 1 0 4 mA current source when P3.5 is low 1 1 10 mA current source when P3.5 is low

1:0 LED0

Reset Value = 00h

Port/LED0Configuration

0 0 Standard C51 Port 0 1 2 mA current source when P3.3 is low 1 0 4 mA current source when P3.3 is low 1 1 10 mA current source when P3.3 is low

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AT89C5131A-L

Serial Peripheral

Slave 1

MISO

MOSI

SCK

MISO MOSI SCK SS

PORT

0 1 2 3

Slave 3

MISO

MOSI

SCK

Slave 4

MISO

MOSI

SCK

Slave 2

MISO

MOSI

SCK

VDD

Master

Interface (SPI)

The Serial Peripheral Interface module (SPI) allows full-duplex, synchronous, serial communication between the MCU and peripheral devices, including other MCUs.

Features

Signal Description

Features of the SPI module include the following:

• Full-duplex, three-wire synchronous transfers

• Master or Slave operation

• Eight programmable Master clock rates

• Serial clock with programmable polarity and phase

• Master mode fault error flag with MCU interrupt capability

• Write collision flag protection

Figure 42 shows a typical SPI bus configuration using one Master controller and many Slave peripherals. The bus is made of three wires connecting all the devices:

Figure 42. SPI Master/Slaves Interconnection

Master Output Slave Input (MOSI)

Master Input Slave Output (MISO)

SPI Serial Clock (SCK) This signal is used to synchronize the data movement both in and out the devices

Slave Select (SS) Each Slave peripheral is selected by one Slave Select pin (SS). This signal must stay

The Master device selects the individual Slave devices by using four pins of a parallel port to control the four SS pins of the Slave devices.

This 1-bit signal is directly connected between the Master Device and a Slave Device. The MOSI line is used to transfer data in series from the Master to the Slave. Therefore, it is an output signal from the Master, and an input signal to a Slave. A byte (8-bit word) is transmitted most significant bit (MSB) first, least significant bit (LSB) last.

This 1-bit signal is directly connected between the Slave Device and a Master Device. The MISO line is used to transfer data in series from the Slave to the Master. Therefore, it is an output signal from the Slave, and an input signal to the Master. A byte (8-bit word) is transmitted most significant bit (MSB) first, least significant bit (LSB) last.

through their MOSI and MISO lines. It is driven by the Master for eight clock cycles which allows to exchange one byte on the serial lines.

low for any message for a Slave. It is obvious that only one Master (SS high level) can drive the network. The Master may select each Slave device by software through port

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AT89C5131A-L

pins (Figure 42). To prevent bus conflicts on the MISO line, only one slave should be selected at a time by the Master for a transmission.

In a Master configuration, the SS line can be used in conjunction with the MODF flag in the SPI Status register (SPSTA) to prevent multiple masters from driving MOSI and SCK (see Section “Error Conditions”, page 95).

A high level on the SS pin puts the MISO line of a Slave SPI in a high-impedance state.

The SS pin could be used as a general-purpose if the following conditions are met:

• The device is configured as a Master and the SSDIS control bit in SPCON is set. This kind of configuration can be found when only one Master is driving the network and there is no way that the SS pin could be pulled low. Therefore, the MODF flag in the SPSTA will never be set

• The Device is configured as a Slave with CPHA and SSDIS control bits set kind of configuration can happen when the system comprises one Master and one Slave only. Therefore, the device should always be selected and there is no reason that the Master uses the SS pin to select the communicating Slave device.

Notes: 1. Clearing SSDIS control bit does not clear MODF.

2. Special care should be taken not to set SSDIS control bit when CPHA =’0’ because in this mode, the SS is used to start the transmission.

(1)

(2)

This

Baud Rate In Master mode, the baud rate can be selected from a baud rate generator which is con-

trolled by three bits in the SPCON register: SPR2, SPR1 and SPR0. The Master clock is chosen from one of seven clock rates resulting from the division of the internal clock by 2, 4, 8, 16, 32, 64 or 128.

Table 72 gives the different clock rates selected by SPR2:SPR1:SPR0:

Table 72. SPI Master Baud Rate Selection

SPR2 SPR1 SPR0 Clock Rate Baud Rate Divisor (BD)

0 0 0 Don’t Use No BRG

0 0 1 F

0 1 0 F

0 1 1 F

1 0 0 F

1 0 1 F

1 1 0 F

1 1 1 Don’t Use No BRG

CLK PERIPH

/4 4

/8 8

/16 16

/32 32

/64 64

/128 128

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AT89C5131A-L

Functional Description

Shift Register

234567

Internal Bus

Pin Control Logic

MISO

MOSI

SCK

Clock Logic

Clock Divider

Clock Select

/64

/128

SPI Interrupt Request

8-bit bus

1-bit signal

FCLK PERIPH

/32

/16

Receive Data Register

SPDAT

SPI Control

SPSTA

CPHA

SPR0

SPR1

CPOLMSTRSSDISSPEN

SPR2

SPCON

WCOL MODFSPIF

- - - -

SSERR

Figure 43 shows a detailed structure of the SPI module.

Figure 43. SPI Module Block Diagram

Operating Modes The Serial Peripheral Interface can be configured as one of the two modes: Master

mode or Slave mode. The configuration and initialization of the SPI module is made through one register:

• The Serial Peripheral CONtrol register (SPCON)

Once the SPI is configured, the data exchange is made using:

• SPCON

• The Serial Peripheral STAtus register (SPSTA)

• The Serial Peripheral DATa register (SPDAT)

During an SPI transmission, data is simultaneously transmitted (shifted out serially) and received (shifted in serially). A serial clock line (SCK) synchronizes shifting and sampling on the two serial data lines (MOSI and MISO). A Slave Select line (SS) allows individual selection of a Slave SPI device; Slave devices that are not selected do not interfere with SPI bus activities.

When the Master device transmits data to the Slave device via the MOSI line, the Slave device responds by sending data to the Master device via the MISO line. This implies full-duplex transmission with both data out and data in synchronized with the same clock (Figure 44).

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Figure 44. Full-duplex Master/Slave Interconnection

8-bit Shift Register

SPI

Clock Generator

Master MCU

8-bit Shift Register

MISOMISO

MOSI

SCK SCK

VSS

VDD

SSSS

Slave MCU

AT89C5131A-L

Master Mode The SPI operates in Master mode when the Master bit, MSTR

is set. Only one Master SPI device can initiate transmissions. Software begins the transmission from a Master SPI module by writing to the Serial Peripheral Data Register (SPDAT). If the shift register is empty, the byte is immediately transferred to the shift register. The byte begins shifting out on MOSI pin under the control of the serial clock, SCK. Simultaneously, another byte shifts in from the Slave on the Master’s MISO pin. The transmission ends when the Serial Peripheral transfer data flag, SPIF, in SPSTA becomes set. At the same time that SPIF becomes set, the received byte from the Slave is transferred to the receive data register in SPDAT. Software clears SPIF by reading the Serial Peripheral Status register (SPSTA) with the SPIF bit set, and then reading the SPDAT.

Slave Mode The SPI operates in Slave mode when the Master bit, MSTR

(2)

cleared. Before a data transmission occurs, the Slave Select pin, SS, of the Slave device must be set to’0’. SS must remain low until the transmission is complete.

In a Slave SPI module, data enters the shift register under the control of the SCK from the Master SPI module. After a byte enters the shift register, it is immediately transferred to the receive data register in SPDAT, and the SPIF bit is set. To prevent an overflow condition, Slave software must then read the SPDAT before another byte enters the shift register

(3)

. A Slave SPI must complete the write to the SPDAT (shift register) at least one bus cycle before the Master SPI starts a transmission. If the write to the data register is late, the SPI transmits the data already in the shift register from the previous transmission.

(1)

, in the SPCON register

, in the SPCON register is

Transmission Formats Software can select any of four combinations of serial clock (SCK) phase and polarity

using two bits in the SPCON: the Clock POLarity (CPOL

(4)

) and the Clock PHAse (CPHA4). CPOL defines the default SCK line level in idle state. It has no significant effect on the transmission format. CPHA defines the edges on which the input data are sampled and the edges on which the output data are shifted (Figure 45 and Figure 46). The clock phase and polarity should be identical for the Master SPI device and the communicating Slave device.

1. The SPI module should be configured as a Master before it is enabled (SPEN set). Also

the Master SPI should be configured before the Slave SPI.

2. The SPI module should be configured as a Slave before it is enabled (SPEN set).

3. The maximum frequency of the SCK for an SPI configured as a Slave is the bus clock

speed.

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4. Before writing to the CPOL and CPHA bits, the SPI should be disabled (SPEN =’0’).

AT89C5131A-L

Figure 45. Data Transmission Format (CPHA = 0)

MSB bit6 bit5 bit4 bit3 bit2 bit1 LSB

bit6 bit5 bit4 bit3 bit2 bit1MSB LSB

1 32 4 5 6 7 8

Capture point

SS (to Slave)

MISO (from Slave)

MOSI (from Master)

SCK (CPOL = 1)

SCK (CPOL = 0)

SPEN (internal)

SCK cycle number

MSB bit6 bit5 bit4 bit3 bit2 bit1 LSB

bit6 bit5 bit4 bit3 bit2 bit1

MSB LSB

1 32 4 5 6 7 8

Capture point

SS (to Slave)

MISO (from Slave)

MOSI (from Master)

SCK (CPOL = 1)

SCK (CPOL = 0)

SPEN (internal)

SCK cycle number

Byte 1 Byte 2

Byte 3

MISO/MOSI

Master SS

Slave SS

(CPHA = 1)

Slave SS

(CPHA = 0)

Figure 46. Data Transmission Format (CPHA = 1)

Figure 47. CPHA/SS Timing

As shown in Figure 46, the first SCK edge is the MSB capture strobe. Therefore the Slave must begin driving its data before the first SCK edge, and a falling edge on the SS pin is used to start the transmission. The SS pin must be toggled high and then low between each byte transmitted (Figure 43).

Figure 47 shows an SPI transmission in which CPHA is’1’. In this case, the Master begins driving its MOSI pin on the first SCK edge. Therefore the Slave uses the first SCK edge as a start transmission signal. The SS pin can remain low between transmissions (Figure 42). This format may be preferable in systems having only one Master and only one Slave driving the MISO data line.

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AT89C5131A-L

Error Conditions The following flags in the SPSTA signal SPI error conditions:

Mode Fault (MODF) Mode Fault error in Master mode SPI indicates that the level on the Slave Select (SS)

pin is inconsistent with the actual mode of the device. MODF is set to warn that there may have a multi-master conflict for system control. In this case, the SPI system is affected in the following ways:

• An SPI receiver/error CPU interrupt request is generated,

• The SPEN bit in SPCON is cleared. This disable the SPI,

• The MSTR bit in SPCON is cleared

When SS DISable (SSDIS) bit in the SPCON register is cleared, the MODF flag is set when the SS signal becomes “0”.

However, as stated before, for a system with one Master, if the SS pin of the Master device is pulled low, there is no way that another Master attempt to drive the network. In this case, to prevent the MODF flag from being set, software can set the SSDIS bit in the SPCON register and therefore making the SS pin as a general-purpose I/O pin.

Clearing the MODF bit is accomplished by a read of SPSTA register with MODF bit set, followed by a write to the SPCON register. SPEN Control bit may be restored to its original set state after the MODF bit has been cleared.

Write Collision (WCOL) A Write Collision (WCOL) flag in the SPSTA is set when a write to the SPDAT register is

done during a transmit sequence.

WCOL does not cause an interruption, and the transfer continues uninterrupted.

Clearing the WCOL bit is done through a software sequence of an access to SPSTA and an access to SPDAT.

Overrun Condition An overrun condition occurs when the Master device tries to send several data bytes

and the Slave devise has not cleared the SPIF bit issuing from the previous data byte transmitted. In this case, the receiver buffer contains the byte sent after the SPIF bit was last cleared. A read of the SPDAT returns this byte. All others bytes are lost.

This condition is not detected by the SPI peripheral.

Interrupts Two SPI status flags can generate a CPU interrupt requests:

Table 73. SPI Interrupts

Flag Request

SPIF (SP Data Transfer) SPI Transmitter Interrupt request

MODF (Mode Fault) SPI Receiver/Error Interrupt Request (if SSDIS = “0”)

Serial Peripheral data transfer flag, SPIF: This bit is set by hardware when a transfer has been completed. SPIF bit generates transmitter CPU interrupt requests.

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Mode Fault flag, MODF: This bit becomes set to indicate that the level on the SS is inconsistent with the mode of the SPI. MODF with SSDIS reset, generates receiver/error CPU interrupt requests.

Figure 48 gives a logical view of the above statements.

AT89C5131A-L

Figure 48. SPI Interrupt Requests Generation

SSDIS

MODF

CPU Interrupt Request

SPI Receiver/Error

CPU Interrupt Request

SPI Transmitter

SPI

CPU Interrupt Request

SPIF

Registers There are three registers in the module that provide control, status and data storage

functions. These registers are describes in the following paragraphs.

Serial Peripheral Control Register (SPCON)

• The Serial Peripheral Control Register does the following:

– Selects one of the Master clock rates

– Configure the SPI module as Master or Slave

– Selects serial clock polarity and phase

– Enables the SPI module

– Frees the SS pin for a general-purpose

Table 74 describes this register and explains the use of each bit.

Table 74. SPCON Register

7 6 5 4 3 2 1 0

SPR2 SPEN SSDIS MSTR CPOL CPHA SPR1 SPR0

Bit

Number Bit Mnemonic Description

7 SPR2

6 SPEN

5 SSDIS

Serial Peripheral Rate 2

Bit with SPR1 and SPR0 define the clock rate.

Serial Peripheral Enable

Cleared to disable the SPI interface.

Set to enable the SPI interface.

SS Disable

Cleared to enable SS in both Master and Slave modes.

Set to disable SS in both Master and Slave modes. In Slave mode, this bit has no effect if CPHA = “0”.

5 MSTR

4 CPOL

3 CPHA

Serial Peripheral Master

Cleared to configure the SPI as a Slave.

Set to configure the SPI as a Master.

Clock Polarity

Cleared to have the SCK set to “0” in idle state.

Set to have the SCK set to “1” in idle state.

Clock Phase

Cleared to have the data sampled when the SCK leaves the idle state (see CPOL).

Set to have the data sampled when the SCK returns to idle state (see CPOL).

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Bit

Number Bit Mnemonic Description

SPR2 SPR1 SPR0 Serial Peripheral Rate

2 SPR1

1 SPR0

000Reserved

00 1F

CLK PERIPH/

010 F

CLK PERIPH/

011F

CLK PERIPH/

100F

CLK PERIPH/

10 1F

CLK PERIPH/

110F

CLK PERIPH/

1 11Reserved

Reset Value = 0001 0100b

Not bit addressable

AT89C5131A-L

128

Serial Peripheral Status Register (SPSTA)

The Serial Peripheral Status Register contains flags to signal the following conditions:

• Data transfer complete

• Write collision

• Inconsistent logic level on SS pin (mode fault error)

Table 75 describes the SPSTA register and explains the use of every bit in the register.

Table 75. SPSTA Register

SPSTA - Serial Peripheral Status and Control register (0C4H)

Table 1.

7 6 5 4 3 2 1 0

SPIF WCOL SSERR MODF - - - -

Bit

Number

7 SPIF

6 WCOL

Bit

Mnemonic Description

Serial Peripheral data transfer flag

Cleared by hardware to indicate data transfer is in progress or has been approved by a clearing sequence.

Set by hardware to indicate that the data transfer has been completed.

Write Collision flag

Cleared by hardware to indicate that no collision has occurred or has been approved by a clearing sequence.

Set by hardware to indicate that a collision has been detected.

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5 SSERR

4 MODF

3 -

Synchronous Serial Slave Error flag

Set by hardware when SS is de-

asserted before the end of a received data.

Cleared by disabling the SPI (clearing SPEN bit in SPCON).

Mode Fault

Cleared by hardware to indicate that the SS pin is at appropriate logic level, or has been approved by a clearing sequence.

Set by hardware to indicate that the SS pin is at inappropriate logic level.

Reserved

The value read from this bit is indeterminate. Do not set this bit

AT89C5131A-L

Bit

Number

Bit

Mnemonic Description

Serial Peripheral Data Register (SPDAT)

2 -

1 -

0 -

Reserved

The value read from this bit is indeterminate. Do not set this bit

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Reset Value = 00X0 XXXXb Not Bit addressable

The Serial Peripheral Data Register (Table 76) is a read/write buffer for the receive data register. A write to SPDAT places data directly into the shift register. No transmit buffer is available in this model.

A Read of the SPDAT returns the value located in the receive buffer and not the content of the shift register.

Table 76. SPDAT Register

SPDAT - Serial Peripheral Data Register (0C5H)

Table 2.

7 6 5 4 3 2 1 0

R7 R6 R5 R4 R3 R2 R1 R0

Reset Value = Indeterminate

R7:R0: Receive data bits

SPCON, SPSTA and SPDAT registers may be read and written at any time while there is no on-going exchange. However, special care should be taken when writing to them while a transmission is on-going:

• Do not change SPR2, SPR1 and SPR0

• Do not change CPHA and CPOL

• Do not change MSTR

• Clearing SPEN would immediately disable the peripheral

• Writing to the SPDAT will cause an overflow

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AT89C5131A-L

SCL

SDA

device2device1 deviceNdevice3

...

Two Wire Interface (

TWI

)

This section describes the 2-wire interface. The 2-wire bus is a bi-directional 2-wire serial communication standard. It is designed primarily for simple but efficient integrated circuit (IC) control. The system is comprised of two lines, SCL (Serial Clock) and SDA (Serial Data) that carry information between the ICs connected to them. The serial data transfer is limited to 100 Kbit/s in standard mode. Various communication configuration can be designed using this bus. Figure 49 shows a typical 2-wire bus configuration. All the devices connected to the bus can be master and slave.

Figure 49. 2-wire Bus Configuration

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AT89C5131A-L

Figure 50. Block Diagram

Address Register

Comparator

Timing & Control logic

Arbitration & Sink Logic

Serial clock generator

Shift Register

Control Register

Status Register

Status Decoder

Input Filter

Output Stage

Input Filter

Output Stage

ACK

Status Bits

Internal Bus

Timer 1 overflow

CLK PERIPH

Interrupt

SDA

SCL

SSADR

SSCON

SSDAT

SSCS

100

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ATMEL AT89C5131A-L User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Features

Description

Block Diagram

Pinout Description

Pinout

Signals

Typical Application

Recommended External components

PCB Recommandations

Clock Controller

Introduction

Oscillator

Registers

SFR Mapping

Dual Data Pointer Register

Program/Code Memory

External Code Memory Access

Flash Memory Architecture

Overview of FM0 Operations

Registers

Flash EEPROM Memory

General Description

Features

Flash Programming and Erasure

Flash Registers and Memory Map

Flash Memory Status

Memory Organization

EEPROM Data Memory

Description

Write Data in the Column Latches

Programming

Read Data

Registers

In-System Programming (ISP)

Flash Programming and Erasure

Boot Process

XROW Bytes

Hardware Conditions

On-chip Expanded RAM (ERAM)

Timer 2

Auto-reload Mode

Programmable Clock Output

Programmable Counter Array (PCA)

PCA Capture Mode

16-bit Software Timer/Compare Mode

High Speed Output Mode

Pulse Width Modulator Mode

PCA Watchdog Timer

Serial I/O Port

Framing Error Detection

Automatic Address Recognition

Baud Rate Selection for UART for Mode 1 and 3

UART Registers

Interrupt System

Overview

Registers

Interrupt Sources and Vector Addresses

Keyboard Interface

Introduction

Description

Registers

Programmable LED

Features

Signal Description

Functional Description