Philips P89C51RA2BA-01, P89C51RA2BBD-01, P89C51RB2BA-01, P89C51RB2BBD-01, P89C51RC2BN-01 User Manual

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INTEGRATED CIRCUITS

P89C51RA2xx/RB2xx/RC2xx/RD2xx

80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

Preliminary data

Supersedes data of 2002 May 20

2002 Jul 18

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Philips Semiconductors Preliminary data

80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

DESCRIPTION

The P89C51RA2/RB2/RC2/RD2xx contains a non-volatile 8KB/16KB/32KB/64KB Flash program memory that is both parallel programmable and serial In-System and In-Application Programmable. In-System Programming (ISP) allows the user to download new code while the microcontroller sits in the application. In-Application Programming (IAP) means that the microcontroller fetches new program code and reprograms itself while in the system. This allows for remote programming over a modem link. A default serial loader (boot loader) program in ROM allows serial In-System programming of the Flash memory via the UART without the need for a loader in the Flash code. For In-Application Programming, the user program erases and reprograms the Flash memory by use of standard routines contained in ROM.

The device supports 6-clock/12-clock mode selection by programming a Flash bit using parallel programming or In-System Programming. In addition, an SFR bit (X2) in the clock control register (CKCON) also selects between 6-clock/12-clock mode.

Additionally, when in 6-clock mode, peripherals may use either 6 clocks per machine cycle or 12 clocks per machine cycle. This choice is available individually for each peripheral and is selected by bits in the CKCON register.

This device is a Single-Chip 8-Bit Microcontroller manufactured in an advanced CMOS process and is a derivative of the 80C51 microcontroller family . The instruction set is 100% compatible with the 80C51 instruction set.

The device also has four 8-bit I/O ports, three 16-bit timer/event counters, a multi-source, four-priority-level, nested interrupt structure, an enhanced UART and on-chip oscillator and timing circuits.

The added features of the P89C51RA2/RB2/RC2/RD2xx make it a powerful microcontroller for applications that require pulse width modulation, high-speed I/O and up/down counting capabilities such as motor control.

FEA TURES

•80C51 Central Processing Unit

•On-chip Flash Program Memory with In-System Programming

•Boot ROM contains low level Flash programming routines for

•Can be programmed by the end-user application (IAP)

•Parallel programming with 87C51 compatible hardware interface

•Supports 6-clock/12-clock mode via parallel programmer (default

•6-clock/12-clock mode Flash bit erasable and programmable via

•6-clock/12-clock mode programmable “on-the-fly” by SFR bit

•Peripherals (PCA, timers, UART) may use either 6-clock or

•Speed up to 20 MHz with 6-clock cycles per machine cycle

•Fully static operation

•RAM expandable externally to 64 kbytes

•Four interrupt priority levels

•Seven interrupt sources

•Four 8-bit I/O ports

•Full-duplex enhanced UART

•Power control modes

•Programmable clock-out pin

•Second DPTR register

•Asynchronous port reset

•Low EMI (inhibit ALE)

•Programmable Counter Array (PCA)

P89C51RA2/RB2/RC2/RD2xx

(ISP) and In-Application Programming (IAP) capability

downloading via the UART

to programmer

clock mode after ChipErase is 12-clock)

ISP

12-clock mode while the CPU is in 6-clock mode

(40 MHz equivalent performance); up to 33 MHz with 12 clocks per machine cycle

– Framing error detection – Automatic address recognition

– Clock can be stopped and resumed – Idle mode – Power down mode

– PWM – Capture/compare

2002 Jul 18

Philips Semiconductors Preliminary data

PART ORDER

VOLTAGE

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

SELECTION TABLE

Serial

Interfaces

UART

CAN

SPI

ADC bits/ch.

I/O Pins

Interrupts

(Ext.)/Levels

Program

Security

Default Clock

Rate1Optional

Max. Freq. at 6-clk / 12-clk

Clock Rate1Reset active

(MHz)

low/high?

Freq. Range at 3V (MHz)

Freq. Range at 5V (MHz)

Type Memory Timers

RAM

ROM

OTP

Flash

P89C51RD2xx 1K – – 64K 4 √ √ √ √ – – – – 32 7(2)/4 √ 12-clk 6-clk H 20/33 – 0-20/33 P89C51RC2xx 512B – – 32K 4 √ √ √ √ – – – – 32 7(2)/4 √ 12-clk 6-clk H 20/33 – 0-20/33 P89C51RB2xx 512B – – 16K 4 √ √ √ √ – – – – 32 7(2)/4 √ 12-clk 6-clk H 20/33 – 0-20/33 P89C51RA2xx 512B – – 8K 4 √ √ √ √ – – – – 32 7(2)/4 √ 12-clk 6-clk H 20/33 – 0-20/33

# of Timers

PWM

PCA

NOTE:

1. P89C51Rx2Hxx devices have a 6-clk default clock rate (12-clk optional). Please also see Device Comparison Table.

DEVICE COMPARISON TABLE

Item 1st generation of Rx2 devices 2nd generation of Rx2 devices

(this data sheet)

Type description P89C51Rx2Hxx(x) P89C51Rx2xx(x) No more letter ‘H’ Programming algo-

rithm

Clock mode (I) 6-clk default, OTP configuration bit

Clock mode (II) N/A 6-clock/12-clock mode programmable

Peripheral clock modes

Flash block structure Two 8-Kbyte blocks

When using a parallel programmer, be sure to select P89C51Rx2Hxx(x) devices

When using a parallel programmer, be sure to select P89C51Rx2xx(x) devices (no more letter ‘H’)

12-clk default, Flash configuration bit to program to 12-clk mode using parallel programmer (cannot be programmed back to 6-clk)

to program to 6-clk mode using paral-

lel programmer or ISP (can be repro-

grammed)

“on the fly” by SFR bit X2 (CKCON.0) N/A Peripherals can be run in 12-clk mode

while CPU runs in 6-clk mode

2–16 4-Kbyte blocks More flexibility

Different programming algorithm due to process change

More flexibility for the end user, more compatibility to older P89C51Rx+ parts

Clock mode can be changed by software

More flexibility , lower power consumption

1–3 16-Kbyte blocks

Difference

ORDERING INFORMATION

NUMBER

MEMORY

FLASH RAM

TEMPERATURE

RANGE (°C)

AND PACKAGE

RANGE

1. P89C51RA2BA/01 8 KB 512 B 0 to +70, PLCC 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT187-2

2. P89C51RA2BBD/01 8 KB 512 B 0 to +70, LQFP 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT389-1

3. P89C51RB2BA/01 16 KB 512 B 0 to +70, PLCC 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT187-2

4. P89C51RB2BBD/01 16 KB 512 B 0 to +70, LQFP 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT389-1

5. P89C51RC2BN/01 32 KB 512 B 0 to +70, PDIP 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT129-1

6. P89C51RC2BA/01 32 KB 512 B 0 to +70, PLCC 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT187-2

7. P89C51RC2FA/01 32 KB 512 B –40 to +85, PLCC 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT187-2

8. P89C51RC2BBD/01 32 KB 512 B 0 to +70, LQFP 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT389-1

9. P89C51RC2FBD/01 32 KB 512 B –40 to +85, LQFP 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT389-1

10. P89C51RD2BN/01 64 KB 1024 B 0 to +70, PDIP 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT129-1

11. P89C51RD2BA/01 64 KB 1024 B 0 to +70, PLCC 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT187-2

12. P89C51RD2BBD/01 64 KB 1024 B 0 to +70, LQFP 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT389-1

13. P89C51RD2FA/01 64 KB 1024 B –40 to +85, PLCC 4.5–5.5 V 0 to 20 MHz 0 to 33 MHz SOT187-2

NOTE:

1. The Part Marking will not include the “/01”.

2002 Jul 18

FREQUENCY (MHz)

6-CLOCK

MODE

12-CLOCK

MODE

DWG #

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

BLOCK DIAGRAM 1

ACCELERATED 80C51 CPU

(12-CLK MODE, 6-CLK MODE)

8K / 16K / 32K /

64 KBYTE

CODE FLASH

FULL-DUPLEX

ENHANCED UART

512 / 1024 BYTE

DATA RAM

TIMER 0 TIMER 1

PORT 3

CONFIGURABLE I/Os

TIMER 2

RESONATOR

PORT 2

CONFIGURABLE I/Os

PORT 1

CONFIGURABLE I/Os

PORT 0

CONFIGURABLE I/Os

OSCILLATORCRYSTAL OR

PROGRAMMABLE COUNTER ARRAY

(PCA)

WATCHDOG TIMER

su01606

2002 Jul 18

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

BLOCK DIAGRAM – CPU ORIENTED

P0.0–P0.7 P2.0–P2.7

PSEN

EAV

ALE

RST

PORT 0

DRIVERS

RAM ADDR REGISTER

TIMING

AND

CONTROL

INSTRUCTION

RAM

ACC

TMP2

PSW

PORT 1

LATCH

PORT 0

LATCH

ALU

TMP1

PORT 2

DRIVERS

PORT 2

LATCH

SFRs

TIMERS

P.C.A.

STACK

POINTER

PORT 3

LATCH

FLASH

PROGRAM

ADDRESS

BUFFER

INCRE-

MENTER

8 16

PROGRAM COUNTER

DPTR’S

MULTIPLE

2002 Jul 18

OSCILLATOR

XTAL1 XTAL2

PORT 1

DRIVERS

P1.0–P1.7

PORT 3

DRIVERS

P3.0–P3.7

SU01065

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

LOGIC SYMBOL

XTAL1

XTAL2

RST

EA/V

PSEN

ALE/PROG RxD TxD

INT0 INT1

PORT 3

SECONDARY FUNCTIONS

PINNING Plastic Dual In-Line Package

T2/P1.0

T2EX/P1.1

CEX0/P1.3 CEX1/P1.4 CEX2/P1.5 CEX3/P1.6 CEX4/P1.7

INT0 INT1

ECI/P1.2

RST RxD/P3.0 TxD/P3.1

/P3.2

/P3.3 T0/P3.4 T1/P3.5

/P3.6

/P3.7

XTAL2 XTAL1

2 3 4 5 6 7 8

9 10 11 12 13 14 15 16 17 18 19 20

DUAL

IN-LINE

PACKAGE

PORT 0

PORT 1PORT 2

P0.0/AD0

39 38

P0.1/AD1

P0.2/AD2

P0.3/AD3

P0.4/AD4

P0.5/AD5

P0.6/AD6

P0.7/AD7

EA/V

ALE/PROG

PSEN

P2.7/A15

P2.6/A14

P2.5/A13

P2.4/A12

P2.3/A11

P2.2/A10

P2.1/A9

P2.0/A8

ADDRESS AND

DATA BUS

T2 T2EX

ADDRESS BUS

SU00021

SU01302

Plastic Leaded Chip Carrier

6140

LCC

18 28

Pin Function

1 NIC* 2 P1.0/T2 3 P1.1/T2EX 4 P1.2/ECI 5 P1.3/CEX0 6 P1.4/CEX1 7 P1.5/CEX2 8 P1.6/CEX3

9 P1.7/CEX4 10 RST 11 P3.0/RxD 12 NIC* 13 P3.1/TxD 14 P3.2/INT0 15 P3.3/INT1

* NO INTERNAL CONNECTION

Pin Function

16 P3.4/T0 17 P3.5/T1 18 P3.6/WR 19 P3.7/RD 20 XTAL2 21 XTAL1 22 V

23 NIC* 24 P2.0/A8 25 P2.1/A9 26 P2.2/A10 27 P2.3/A11 28 P2.4/A12 29 P2.5/A13 30 P2.6/A14

Plastic Quad Flat Pack

44 34

LQFP

12 22

Pin Function

1 P1.5/CEX2 2 P1.6/CEX3 3 P1.7/CEX4 4 RST 5 P3.0/RxD 6 NIC* 7 P3.1/TxD 8 P3.2/INT0

9 P3.3/INT1 10 P3.4/T0 11 P3.5/T1 12 P3.6/WR 13 P3.7/RD 14 XTAL2 15 XTAL1

* NO INTERNAL CONNECTION

Pin Function

16 V

17 NIC* 18 P2.0/A8 19 P2.1/A9 20 P2.2/A10 21 P2.3/A11 22 P2.4/A12 23 P2.5/A13 24 P2.6/A14 25 P2.7/A15 26 PSEN 27 ALE/PROG 28 NIC* 29 EA

30 P0.7/AD7

Pin Function

31 P2.7/A15 32 PSEN 33 ALE/PROG 34 NIC* 35 EA/V 36 P0.7/AD7 37 P0.6/AD6 38 P0.5/AD5 39 P0.4/AD4 40 P0.3/AD3 41 P0.2/AD2 42 P0.1/AD1 43 P0.0/AD0 44 V

SU00023

Pin Function

31 P0.6/AD6 32 P0.5/AD5 33 P0.4/AD4 34 P0.3/AD3 35 P0.2/AD2 36 P0.1/AD1 37 P0.0/AD0 38 V

39 NIC* 40 P1.0/T2 41 P1.1/T2EX 42 P1.2/ECI 43 P1.3/CEX0

44 P1.4/CEX1

SU01400

2002 Jul 18

Philips Semiconductors Preliminary data

MNEMONIC

TYPE

NAME AND FUNCTION

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

PIN DESCRIPTIONS

PIN NUMBER

PDIP PLCC LQFP

P0.0–0.7 39–32 43–36 37–30 I/O Port 0: Port 0 is an open-drain, bidirectional I/O port. Port 0 pins that have 1s

P1.0–P1.7 1–8 2–9 40–44,

P2.0–P2.7 21–28 24–31 18–25 I/O Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. Port 2 pins that

P3.0–P3.7 10–17 11,

RST 9 10 4 I Reset: A high on this pin for two machine cycles while the oscillator is running,

ALE 30 33 27 O Address Latch Enable: Output pulse for latching the low byte of the address

20 22 16 I Ground: 0 V reference. 40 44 38 I Power Supply: This is the power supply voltage for normal, idle, and power-down

operation.

written to them float and can be used as high-impedance inputs. Port 0 is also the multiplexed low-order address and data bus during accesses to external program

and data memory. In this application, it uses strong internal pull-ups when emitting 1s.

I/O Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups on all pins.

1–3

Port 1 pins that have 1s written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs, port 1 pins that are externally pulled low will source current because of the internal pull-ups. (See DC Electrical Characteristics:

Alternate functions for P89C51RA2/RB2/RC2/RD2xx Port 1 include:

1 2 40 I/O T2 (P1.0): Timer/Counter 2 external count input/Clockout (see Programmable

Clock-Out) 2 3 41 I T2EX (P1.1): Timer/Counter 2 Reload/Capture/Direction Control 3 4 42 I ECI (P1.2): External Clock Input to the PCA 4 5 43 I/O CEX0 (P1.3): Capture/Compare External I/O for PCA module 0 5 6 44 I/O CEX1 (P1.4): Capture/Compare External I/O for PCA module 1 6 7 1 I/O CEX2 (P1.5): Capture/Compare External I/O for PCA module 2 7 8 2 I/O CEX3 (P1.6): Capture/Compare External I/O for PCA module 3 8 9 3 I/O CEX4 (P1.7): Capture/Compare External I/O for PCA module 4

have 1s written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs, port 2 pins that are externally being pulled low will source current because of the internal pull-ups. (See DC Electrical Characteristics: I emits the high-order address byte during fetches from external program memory

). Port 2

and during accesses to external data memory that use 16-bit addresses (MOVX @DPTR). In this application, it uses strong internal pull-ups when emitting 1s. During accesses to ext ernal data memory that use 8 -bit addres ses (MOV @Ri), port 2 emits the contents of the P2 special function register.

5, 7–13 I/O Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins that

13–19

have 1s written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs, port 3 pins that are externally being pulled low will source current because of the pull-ups. (See DC Electrical Characteristics: I the special features of the P89C51RA2/RB2/RC2/RD2xx, as listed below:

). Port 3 also serves

10 11 5 I RxD (P3.0): Serial input port 11 13 7 O TxD (P3.1): Serial output port 12 14 8 I INT0 (P3.2): External interrupt 13 15 9 I INT1 (P3.3): External interrupt 14 16 10 I T0 (P3.4): Timer 0 external input 15 17 11 I T1 (P3.5): Timer 1 external input 16 18 12 O WR (P3.6): External data memory write strobe 17 19 13 O RD (P3.7): External data memory read strobe

resets the device. An internal resistor to V an external capacitor to V

permits a power-on reset using only

during an access to external memory. In normal operation, ALE is emitted twice every machine cycle, and can be used for external timing or clocking. Note that one ALE pulse is skipped during each access to external data memory. ALE can be disabled by setting SFR auxiliary.0. With this bit set, ALE will be active only during a MOVX instruction.

2002 Jul 18

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

MNEMONIC NAME AND FUNCTIONTYPE

PSEN 29 32 26 O Program Store Enable: The read strobe to external program memory. When

EA/V

XTAL1 19 21 15 I Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock

XTAL2 18 20 14 O Crystal 2: Output from the inverting oscillator amplifier.

NOTE:

To avoid “latch-up” effect at power-on, the voltage on any pin (other than V

PIN NUMBER

LQFPPLCCPDIP

executing code from the external program memory, PSEN machine cycle, except that two PSEN to external data memory. PSEN program memory.

31 35 29 I External Access Enable/Programming Supply V oltage: EA must be externally

held low to enable the device to fetch code from external program memory locations. If EA The value on the EA changes have no effect. This pin also receives the programming supply voltage

) during Flash programming.

generator circuits.

is held high, the device executes from internal program memory.

pin is latched when RST is released and any subsequent

) must not be higher than VCC + 0.5 V or less than VSS – 0.5 V.

activations are skipped during each access

is not activated during fetches from internal

is activated twice each

2002 Jul 18

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

Table 1. Special Function Registers

SYMBOL DESCRIPTION

ACC* Accumulator E0H E7 E6 E5 E4 E3 E2 E1 E0 00H AUXR# Auxiliary 8EH – – – – – – AUXR1# Auxiliary 1 A2H – – B* B register F0H F7 F6 F5 F4 F3 F2 F1 F0 00H CCAP0H# Module 0 Capture High FAH xxxxxxxxB

CCAP1H# Module 1 Capture High FBH xxxxxxxxB CCAP2H# Module 2 Capture High FCH xxxxxxxxB CCAP3H# Module 3 Capture High FDH xxxxxxxxB CCAP4H# Module 4 Capture High FEH xxxxxxxxB CCAP0L# Module 0 Capture Low EAH xxxxxxxxB CCAP1L# Module 1 Capture Low EBH xxxxxxxxB CCAP2L# Module 2 Capture Low ECH xxxxxxxxB CCAP3L# Module 3 Capture Low EDH xxxxxxxxB CCAP4L# Module 4 Capture Low EEH xxxxxxxxB

CCAPM0# Module 0 Mode DAH – ECOM CAPP CAPN MAT TOG PWM ECCF x0000000B CCAPM1# Module 1 Mode DBH – ECOM CAPP CAPN MAT TOG PWM ECCF x0000000B CCAPM2# Module 2 Mode DCH – ECOM CAPP CAPN MAT TOG PWM ECCF x0000000B CCAPM3# Module 3 Mode DDH – ECOM CAPP CAPN MAT TOG PWM ECCF x0000000B CCAPM4# Module 4 Mode DEH – ECOM CAPP CAPN MAT TOG PWM ECCF x0000000B

CCON*# PCA Counter Control D8H CF CR – CCF4 CCF3 CCF2 CCF1 CCF0 00x00000B CH# PCA Counter High F9H 00H

CKCON# Clock control 8FH – WDX2 PCAX2 SIX2 T2X2 T1X2 T0X2 X2 x0000000B CL# PCA Counter Low E9H 00H

CMOD# PCA Counter Mode D9H CIDL WDTE – – – CPS1 CPS0 ECF 00xxx000B DPTR: Data Pointer (2 bytes)

DPH Data Pointer High 83H 00H DPL Data Pointer Low 82H 00H

IE* Interrupt Enable 0 A8H EA EC ET2 ES ET1 EX1 ET0 EX0 00H

IP* Interrupt Priority B8H – PPC PT2 PS PT1 PX1 PT0 PX0 x0000000B IPH# Interrupt Priority High B7H – PPCH PT2H PSH PT1H PX1H PT0H PX0H x0000000B

DIRECT

ADDRESS

BIT ADDRESS, SYMBOL, OR ALTERNATIVE PORT FUNCTION

MSB LSB

EXTRAM

ENBOOT

DF DE DD DC DB DA D9 D8

AF AE AD AC AB AA A9 A8

BF BE BD BC BB BA B9 B8

– GF2 0 – DPS xxxxxxx0B

AO xxxxxx00B

RESET VALUE

87 86 85 84 83 82 81 80

P0* Port 0 80H AD7 AD6 AD5 AD4 AD3 AD2 AD1 AD0 FFH

97 96 95 94 93 92 91 90

P1* Port 1 90H CEX4 CEX3 CEX2 CEX1 CEX0 ECI T2EX T2 FFH

A7 A6 A5 A4 A3 A2 A1 A0

P2* Port 2 A0H AD15 AD14 AD13 AD12 AD11 AD10 AD9 AD8 FFH

B7 B6 B5 B4 B3 B2 B1 B0

P3* Port 3 B0H RD WR T1 T0 INT1 INT0 TxD RxD FFH

PCON#1Power Control 87H SMOD1 SMOD0 – POF GF1 GF0 PD IDL 00xxx000B

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

1. Reset value depends on reset source.

2002 Jul 18

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

Table 1. Special Function Registers (Continued)

SYMBOL DESCRIPTION

PSW* Program Status Word D0H CY AC F0 RS1 RS0 OV F1 P 00000000B

RCAP2H# Timer 2 Capture High CBH 00H RCAP2L# Timer 2 Capture Low CAH 00H

SADDR# Slave Address A9H 00H SADEN# Slave Address Mask B9H 00H

SBUF Serial Data Buffer 99H xxxxxxxxB

SCON* Serial Control 98H SP Stack Pointer 81H 07H

TCON* Timer Control 88H TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 00H

DIRECT

ADDRESS

BIT ADDRESS, SYMBOL, OR ALTERNATIVE PORT FUNCTION

MSB LSB

D7 D6 D5 D4 D3 D2 D1 D0

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

SM0/FE

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

SM1 SM2 REN TB8 RB8 TI RI 00H

RESET VALUE

CF CE CD CC CB CA C9 C8 T2CON* Timer 2 Control C8H TF2 EXF2 RCLK TCLK EXEN2 TR2 C/T2 CP/RL2 00H T2MOD# Timer 2 Mode Control C9H – – – – – – T2OE DCEN xxxxxx00B TH0 Timer High 0 8CH 00H

TH1 Timer High 1 8DH 00H TH2# T imer High 2 CDH 00H TL0 Timer Low 0 8AH 00H TL1 Timer Low 1 8BH 00H TL2# Timer Low 2 CCH 00H

TMOD Timer Mode 89H GATE C/T M1 M0 GATE C/T M1 M0 00H WDTRST W atchdog Timer Reset A6H

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

OSCILLA T OR CHARACTERISTICS

XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier. The pins can be configured for use as an on-chip oscillator.

To drive the device from an external clock source, XTAL1 should be driven while XTAL2 is left unconnected. Minimum and maximum high and low times specified in the data sheet must be observed.

This device is configured at the factory to operate using 12 clock periods per machine cycle, referred to in this datasheet as “12-clock mode”. It may be optionally configured on commercially available Flash programming equipment or via ISP or via software to operate at 6 clocks per machine cycle, referred to in this datasheet as “6-clock mode”. (This yields performance equivalent to twice that of standard 80C51 family devices). Also see next page.

2002 Jul 18

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

CLOCK CONTROL REGISTER (CKCON)

This device provides control of the 6-clock/12-clock mode by means of both an SFR bit (X2) and a Flash bit (FX2, located in the Security Block). The Flash clock control bit, FX2, when programmed (6-clock mode) supercedes the X2 bit (CKCON.0).

CKCON Address = 8Fh Reset Value = x0000000B

Not Bit Addressable

76543210

BIT SYMBOL FUNCTION

CKCON.7 – Reserved. CKCON.6 WDX2 Watchdog clock; 0 = 6 clocks for each WDT clock, 1 = 12 clocks for each WDT clock CKCON.5 PCAX2 PCA clock; 0 = 6 clocks for each PCA clock, 1 = 12 clocks for each PCA clock CKCON.4 SIX2 UART clock; 0 = 6 clocks for each UART clock, 1 = 12 clocks for each UART clock CKCON.3 T2X2 Timer2 clock; 0 = 6 clocks for each Timer2 clock, 1 = 12 clocks for each Timer2 clock CKCON.2 T1X2 Timer1 clock; 0 = 6 clocks for each Timer1 clock, 1 = 12 clocks for each Timer1 clock CKCON.1 T0X2 Timer0 clock; 0 = 6 clocks for each Timer0 clock, 1 = 12 clocks for each Timer0 clock CKCON.0 X2 CPU clock; 1 = 6 clocks for each machine cycle, 0 = 12 clocks for each machine cycle

The CKCON register also provides individual control of the clock rates for the peripherals devices. When running in 6-clock mode each peripheral may be individually clocked from either fosc/6 or fosc/12. When in 12-clock mode, all peripheral devices will use fosc/12. The CKCON register is shown below.

T0X2T1X2T2X2SIX2PCAX2WDX2–

SU01607

Bits 1 through 6 only apply if 6 clocks per machine cycle is chosen (i.e.– Bit 0 = 1). If Bit 0 = 0 (12 clocks per machine cycle) then all peripherals will have 12 clocks per machine cycle as their clock source.

FX2 clock mode bit

erased 0 x 12-clock (default) 12-clock (default) erased 1 0 6-clock 6-clock

erased 1 1 6-clock 12-clock programmed x 0 6-clock 6-clock programmed x 1 6-clock 12-clock

X2 Peripheral clock

mode bit

(e.g., T0X2)

Also please note that the clock divider applies to the serial port for modes 0 & 2 (fixed baud rate modes). This is because modes 1 & 3 (variable baud rate modes) use either Timer 1 or Timer 2.

Below is the truth table for the peripheral input clock sources.

CPU MODE Peripheral Clock Rate

RESET

A reset is accomplished by holding the RST pin high for at least two machine cycles (12 oscillator periods in 6-clock mode, or 24 oscillator periods in 12-clock mode), while the oscillator is running. To ensure a good power-on reset, the RST pin mu st be h i gh l o n g enough to allow the oscillator time to start up (normally a few milliseconds) plus two machine cycles. At power-on, the voltage on V come up at the same time for a proper start-up. Ports 1, 2, and 3 will asynchronously be driven to their reset condition when a voltage above V

The value on the EA no further effect.

(min.) is applied to RST.

IH1

pin is latched when RST is deasserted and has

and RST must

2002 Jul 18

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

LOW POWER MODES Stop Clock Mode

The static design enables the clock speed to be reduced down to 0 MHz (stopped). When the oscillator is stopped, the RAM and Special Function Registers retain their values. This mode allows step-by-step utilization and permits reduced system power consumption by lowering the clock frequency down to any value. For lowest power consumption the Power Down mode is suggested.

Idle Mode

In the idle mode (see Table 2), the CPU puts itself to sleep while all of the on-chip peripherals stay active. The instruction to invoke the idle mode is the last instruction executed in the normal operating mode before the idle mode is activated. The CPU contents, the on-chip RAM, and all of the special function registers remain intact during this mode. The idle mode can be terminated either by any enabled interrupt (at which time the process is picked up at the interrupt service routine and continued), or by a hardware reset which starts the processor in the same manner as a power-on reset.

Power-Down Mode

To save even more power, a Power Down mode (see Table 2) can be invoked by software. In this mode, the oscillator is stopped and the instruction that invoked Power Down is the last instruction executed. The on-chip RAM and Special Function Registers retain their values down to 2 V and care must be taken to return V minimum specified operating voltages before the Power Down Mode is terminated.

Either a hardware reset or external interrupt can be used to exit from Power Down. Reset redefines all the SFRs but does not change the on-chip RAM. An external interrupt allows both the SFRs and the on-chip RAM to retain their values.

To properly terminate Power Down, the reset or external interrupt should not be executed before V operating level and must be held active long enough for the oscillator to restart and stabilize (normally less than 10 ms).

With an external interrupt, INT0 and INT1 must be enabled and

configured as level-sensitive. Holding the pin low restarts the oscillator

but bringing the pin back high completes the exit. Once the interrupt is serviced, the next instruction to be executed after RETI will be the one following the instruction that put the device into Power Down.

is restored to its normal

to the

POWER-ON FLAG

The Power-On Flag (POF) is set by on-chip circuitry when the V level on the P89C51RA2/RB2/RC2/RD2xx rises from 0 to 5 V . The POF bit can be set or cleared by software allowing a user to determine if the reset is the result of a power-on or a warm start after powerdown. The V to remain unaffected by the V

level must remain above 3 V for the POF

level.

Design Consideration

When the idle mode is terminated by a hardware reset, the device normally resumes program execution, from where it left off, up to two machine cycles before the internal reset algorithm takes control. On-chip hardware inhibits access to internal RAM in this event, but access to the port pins is not inhibited. To eliminate the possibility of an unexpected write when Idle is terminated by reset, the instruction following the one that invokes Idle should not be one that writes to a port pin or to external memory.

ONCE Mode

The ONCE (“On-Circuit Emulation”) Mode facilitates testing and debugging of systems without the device having to be removed from the circuit. The ONCE Mode is invoked by:

1. Pull ALE low while the device is in reset and PSEN is high;

2. Hold ALE low as RST is deactivated. While the device is in ONCE Mode, the Port 0 pins go into a float

state, and the other port pins and ALE and PSEN high. The oscillator circuit remains active. While the device is in this mode, an emulator or test CPU can be used to drive the circuit. Normal operation is restored when a normal reset is applied.

are weakly pulled

Programmable Clock-Out

A 50% duty cycle clock can be programmed to come out on P1.0. This pin, besides being a regular I/O pin, has two alternate functions. It can be programmed:

1. to input the external clock for Timer/Counter 2, or

2. to output a 50% duty cycle clock ranging from 61 Hz to 4 MHz at a 16 MHz operating frequency in 12-clock mode (122 Hz to 8 MHz in 6-clock mode).

To configure the Timer/Counter 2 as a clock generator, bit C/T T2CON) must be cleared and bit T20E in T2MOD must be set. Bit TR2 (T2CON.2) also must be set to start the timer.

The Clock-Out frequency depends on the oscillator frequency and the reload value of Timer 2 capture registers (RCAP2H, RCAP2L) as shown in this equation:

Oscillator Frequency

n (65536 * RCAP2H, RCAP2L)

n = 2 in 6-clock mode

Where (RCAP2H,RCAP2L) = the content of RCAP2H and RCAP2L taken as a 16-bit unsigned integer.

In the Clock-Out mode Timer 2 roll-overs will not generate an interrupt. This is similar to when it is used as a baud-rate generator. It is possible to use Timer 2 as a baud-rate generator and a clock generator simultaneously. Note, however, that the baud-rate and the Clock-Out frequency will be the same.

4 in 12-clock mode

2 (in

Table 2. External Pin Status During Idle and Power-Down Mode

MODE PROGRAM MEMOR Y ALE PSEN PORT 0 PORT 1 PORT 2 PORT 3

Idle Internal 1 1 Data Data Data Data Idle External 1 1 Float Data Address Data Power-down Internal 0 0 Data Data Data Data Power-down External 0 0 Float Data Data Data

2002 Jul 18

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

TIMER 0 AND TIMER 1 OPERATION Timer 0 and Timer 1

The “Timer” or “Counter” function is selected by control bits C/T in the Special Function Register TMOD. These two Timer/Counters have four operating modes, which are selected by bit-pairs (M1, M0) in TMOD. Modes 0, 1, and 2 are the same for both Timers/Counters. Mode 3 is different. The four operating modes are described in the following text.

Mode 0

Putting either Timer into Mode 0 makes it look like an 8048 T imer, which is an 8-bit Counter with a divide-by-32 prescaler. Figure 2 shows the Mode 0 operation.

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

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

Mode 0 operation is the same for Timer 0 as for Timer 1. There are two different GA TE bits, one for Timer 1 (TMOD.7) and one for Timer 0 (TMOD.3).

= 1. (Setting GATE = 1 allows the

, to facilitate pulse width

Mode 1

Mode 1 is the same as Mode 0, except that the Timer register is being run with all 16 bits.

Mode 2

Mode 2 configures the Timer register as an 8-bit Counter (TLn) with automatic reload, as shown in Figure 4. Overflow from TLn not only sets TFn, but also reloads TLn with the contents of THn, which is preset by software. The reload leaves THn unchanged.

Mode 2 operation is the same for Timer 0 as for Timer 1.

Mode 3

Timer 1 in Mode 3 simply holds its count. The effect is the same as setting TR1 = 0.

Timer 0 in Mode 3 establishes TL0 and TH0 as two separate counters. The logic for Mode 3 on Timer 0 is shown in Figure 5. TL0 uses the Timer 0 control bits: C/T pin INT0 cycles) and takes over the use of TR1 and TF1 from Timer 1. Thus, TH0 now controls the “Timer 1” interrupt.

Mode 3 is provided for applications requiring an extra 8-bit timer on the counter. With Timer 0 in Mode 3, an 80C51 can look like it has three Timer/Counters. When Timer 0 is in Mode 3, Timer 1 can be turned on and off by switching it out of and into its own Mode 3, or can still be used by the serial port as a baud rate generator, or in fact, in any application not requiring an interrupt.

. TH0 is locked into a timer function (counting machine

, GATE, TR0, and TF0 as well as

TMOD Address = 89H Reset Value = 00H

Not Bit Addressable

76543 2 1 0

GATE C/T M1

TIMER 1 TIMER 0

BIT SYMBOL FUNCTION

TMOD.3/ GATE Gating control when set. Timer/Counter “n” is enabled only while “INTn TMOD.7 “TRn” control pin is set. when cleared Timer “n” is enabled whenever “TRn” control bit is set.

TMOD.2/ C/T TMOD.6 Set for Counter operation (input from “Tn” input pin).

M1 M0 OPERATING

0 0 8048 Timer: “TLn” serves as 5-bit prescaler. 0 1 16-bit Timer/Counter: “THn” and “TLn” are cascaded; there is no prescaler. 1 0 8-bit auto-reload Timer/Counter: “THn” holds a value which is to be reloaded

1 1 (Timer 0) TL0 is an 8-bit Timer/Counter controlled by the standard Timer 0 control bits.

1 1 (Timer 1) Timer/Counter 1 stopped.

Timer or Counter Selector cleared for Timer operation (input from internal system clock.)

into “TLn” each time it overflows.

TH0 is an 8-bit timer only controlled by Timer 1 control bits.

M0 GATE C/T

M1 M0

” pin is high and

SU01580

2002 Jul 18

Figure 1. Timer/Counter 0/1 Mode Control (TMOD) Register

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

OSC

Timer n Gate bit

INTn Pin

*d = 6 in 6-clock mode; d = 12 in 12-clock mode.

Tn Pin

÷ d*

TRn

C/T = 0

C/T = 1

Control

TLn

(5 Bits)

THn

(8 Bits)

TFn Interrupt

SU01618

Figure 2. Timer/Counter 0/1 Mode 0: 13-Bit Timer/Counter

TCON Address = 88H Reset Value = 00H

Bit Addressable

76543210

IE0IT1IE1TR0TF0TR1TF1

IT0

BIT SYMBOL FUNCTION

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

Cleared by hardware when processor vectors to interrupt routine, or clearing the bit in software. TCON.6 TR1 Timer 1 Run control bit. Set/cleared by software to turn Timer/Counter on/off. TCON.5 TF0 Timer 0 overflow flag. Set by hardware on Timer/Counter overflow.

Cleared by hardware when processor vectors to interrupt routine, or by clearing the bit in software. TCON.4 TR0 Timer 0 Run control bit. Set/cleared by software to turn Timer/Counter on/off. TCON.3 IE1 Interrupt 1 Edge flag. Set by hardware when external interrupt edge detected.

Cleared when interrupt processed. TCON.2 IT1 Interrupt 1 type control bit. Set/cleared by software to specify falling edge/low level triggered

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

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

triggered external interrupts.

SU01516

2002 Jul 18

Figure 3. Timer/Counter 0/1 Control (TCON) Register

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

OSC

Timer n Gate bit

INTn Pin

*d = 6 in 6-clock mode; d = 12 in 12-clock mode.

OSC

Timer 0 Gate bit

÷ d*

Tn Pin

TRn

÷ d*

T0 Pin

TR0

C/T = 0

C/T

= 1

Control

TLn

(8 Bits)

THn

(8 Bits)

Reload

Figure 4. Timer/Counter 0/1 Mode 2: 8-Bit Auto-Reload

C/T = 0

C/T

= 1

Control

TL0

(8 Bits)

TFn

TF0

Interrupt

SU01619

Interrupt

INT0 Pin

OSC

*d = 6 in 6-clock mode; d = 12 in 12-clock mode.

÷ d*

TH0

(8 Bits)

Control

TR1

Figure 5. Timer/Counter 0 Mode 3: Two 8-Bit Counters

TF1

Interrupt

SU01620

2002 Jul 18

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

TIMER 2 OPERATION Timer 2

Timer 2 is a 16-bit Timer/Counter which can operate as either an event timer or an event counter, as selected by C/T function register T2CON (see Figure 6). Timer 2 has three operating modes: Capture, Auto-reload (up or down counting), and Baud Rate Generator, which are selected by bits in the T2CON as shown in Table 3.

2 in the special

Capture Mode

In the capture mode there are two options which are selected by bit EXEN2 in T2CON. If EXEN2=0, then timer 2 is a 16-bit timer or counter (as selected by C/T sets bit TF2, the timer 2 overflow bit. This bit can be used to generate an interrupt (by enabling the Timer 2 interrupt bit in the IE register). If EXEN2= 1, Timer 2 operates as described above, but with the added feature that a 1- to -0 transition at external input T2EX causes the current value in the Timer 2 registers, TL2 and TH2, to be captured into registers RCAP2L and RCAP2H, respectively. In addition, the transition at T2EX causes bit EXF2 in T2CON to be set, and EXF2 like TF2 can generate an interrupt (which vectors to the same location as Timer 2 overflow interrupt. The Timer 2 interrupt service routine can interrogate TF2 and EXF2 to determine which event caused the interrupt). The capture mode is illustrated in Figure 7 (There is no reload value for TL2 and TH2 in this mode. Even when a capture event occurs from T2EX, the counter keeps on counting T2EX pin transitions or osc/6 pulses (osc/12 in 12-clock mode).).

2 in T2CON) which, upon overflowing

Auto-Reload Mode (Up or Down Counter)

In the 16-bit auto-reload mode, Timer 2 can be configured (as either a timer or counter [C/T or down. The counting direction is determined by bit DCEN (Down

2 in T2CON]) then programmed to count up

Counter Enable) which is located in the T2MOD register (see Figure 8). When reset is applied the DCEN=0 which means Timer 2 will default to counting up. If DCEN bit is set, Timer 2 can count up or down depending on the value of the T2EX pin.

Figure 9 shows Timer 2 which will count up automatically since DCEN=0. In this mode there are two options selected by bit EXEN2 in T2CON register. If EXEN2=0, then T imer 2 counts up to 0FFFFH and sets the TF2 (Overflow Flag) bit upon overflow. This causes the Timer 2 registers to be reloaded with the 16-bit value in RCAP2L and RCAP2H. The values in RCAP2L and RCAP2H are preset by software means.

If EXEN2=1, then a 16-bit reload can be triggered either by an overflow or by a 1-to-0 transition at input T2EX. This transition also sets the EXF2 bit. The Timer 2 interrupt, if enabled, can be generated when either TF2 or EXF2 are 1.

In Figure 10 DCEN=1 which enables Timer 2 to count up or down. This mode allows pin T2EX to control the direction of count. When a logic 1 is applied at pin T2EX Timer 2 will count up. Timer 2 will overflow at 0FFFFH and set the TF2 flag, which can then generate an interrupt, if the interrupt is enabled. This timer overflow also causes the 16-bit value in RCAP2L and RCAP2H to be reloaded into the timer registers TL2 and TH2.

When a logic 0 is applied at pin T2EX this causes Timer 2 to count down. The timer will underflow when TL2 and TH2 become equal to the value stored in RCAP2L and RCAP2H. Timer 2 underflow sets the TF2 flag and causes 0FFFFH to be reloaded into the timer registers TL2 and TH2.

The external flag EXF2 toggles when Timer 2 underflows or overflows. This EXF2 bit can be used as a 17th bit of resolution if needed. The EXF2 flag does not generate an interrupt in this mode of operation.

(MSB) (LSB)

TF2 EXF2 RCLK TCLK EXEN2 TR2 C/T

Symbol Position Name and Significance

TF2 T2CON.7 Timer 2 overflow flag set by a Timer 2 overflow and must be cleared by software. TF2 will not be set

EXF2 T2CON.6 Timer 2 external flag set when either a capture or reload is caused by a negative transition on T2EX and

RCLK T2CON.5 Receive clock flag. When set, causes the serial port to use Timer 2 overflow pulses for its receive clock

TCLK T2CON.4 Transmit clock flag. When set, causes the serial port to use Timer 2 overflow pulses for its transmit clock

EXEN2 T2CON.3 Timer 2 external enable flag. When set, allows a capture or reload to occur as a result of a negative

TR2 T2CON.2 Start/stop control for Timer 2. A logic 1 starts the timer. C/T

2 T2CON.1 Timer or counter select. (Timer 2)

CP/RL

2 T2CON.0 Capture/Reload flag. When set, captures will occur on negative transitions at T2EX if EXEN2 = 1. When

when either RCLK or TCLK = 1.

EXEN2 = 1. When Timer 2 interrupt is enabled, EXF2 = 1 will cause the CPU to vector to the Timer 2 interrupt routine. EXF2 must be cleared by software. EXF2 does not cause an interrupt in up/down counter mode (DCEN = 1).

in modes 1 and 3. RCLK = 0 causes Timer 1 overflow to be used for the receive clock.

in modes 1 and 3. TCLK = 0 causes Timer 1 overflows to be used for the transmit clock.

transition on T2EX if Timer 2 is not being used to clock the serial port. EXEN2 = 0 causes Timer 2 to ignore events at T2EX.

0 = Internal timer (OSC/6 in 6-clock mode or OSC/12 in 12-clock mode) 1 = External event counter (falling edge triggered).

cleared, auto-reloads will occur either with Timer 2 overflows or negative transitions at T2EX when EXEN2 = 1. When either RCLK = 1 or TCLK = 1, this bit is ignored and the timer is forced to auto-reload on Timer 2 overflow .

Figure 6. Timer/Counter 2 (T2CON) Control Register

2 CP/RL2

SU01251

2002 Jul 18

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

Table 3. Timer 2 Operating Modes

RCLK + TCLK CP/RL2 TR2 MODE

0 0 1 16-bit Auto-reload 0 1 1 16-bit Capture 1 X 1 Baud rate generator X X 0 (off)

OSC

T2 Pin

T2EX Pin

÷ n*

Transition

Detector

C/T2 = 0

C/T

2 = 1

EXEN2

Control

TR2

Control

Capture

TL2

(8 BITS)

RCAP2L RCAP2H

TH2

(8 BITS)

TF2

EXF2

* n = 6 in 6-clock mode, or 12 in 12-clock mode.

Figure 7. Timer 2 in Capture Mode

T2MOD Address = 0C9H Reset Value = XXXX XX00B

Not Bit Addressable

— — — — — — T2OE DCEN

Timer 2

Interrupt

SU01252

Bit

76543210

Symbol Function

— Not implemented, reserved for future use.* T2OE Timer 2 Output Enable bit. DCEN Down Count Enable bit. When set, this allows Timer 2 to be configured as an up/down counter.

* User software should not write 1s to reserved bits. These bits may be used in future 8051 family products to invoke new features.

In that case, the reset or inactive value of the new bit will be 0, and its active value will be 1. The value read from a reserved bit is indeterminate.

Figure 8. Timer 2 Mode (T2MOD) Control Register

2002 Jul 18

SU00729

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

OSC

T2 PIN

T2EX PIN

÷ n*

TRANSITION

DETECTOR

C/T2 = 0

2 = 1

C/T

CONTROL

EXEN2

* n = 6 in 6-clock mode, or 12 in 12-clock mode.

Figure 9. Timer 2 in Auto-Reload Mode (DCEN = 0)

TL2

(8 BITS)

CONTROL

TR2

RELOAD

RCAP2L RCAP2H

(DOWN COUNTING RELOAD VALUE)

FFH FFH

TH2

(8 BITS)

TF2

EXF2

TOGGLE

TIMER 2

INTERRUPT

SU01253

T2 PIN

÷ n*

C/T2 = 0

C/T

2 = 1

CONTROL

TR2

OSC

* n = 6 in 6-clock mode, or 12 in 12-clock mode.

Figure 10. Timer 2 Auto Reload Mode (DCEN = 1)

TL2 TH2

OVERFLOW

RCAP2L RCAP2H

(UP COUNTING RELOAD VALUE) T2EX PIN

COUNT DIRECTION 1 = UP 0 = DOWN

TF2

EXF2

INTERRUPT

SU01254

2002 Jul 18

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

Timer 1

Overflow

n = 1 in 6-clock mode n = 2 in 12-clock mode

OSC

÷ n

T2 Pin

Transition

Detector

C/T2 = 0

2 = 1

C/T

TR2

Control

TL2

(8-bits)

RCAP2L RCAP2H

TH2

(8-bits)

Reload

÷ 2

“0” “1”

“0”“1”

÷ 16

SMOD

RCLK

RX Clock

TCLK

TX Clock

T2EX Pin

Control

EXEN2

Note availability of additional external interrupt.

EXF2

Figure 11. T imer 2 in Baud Rate Generator Mode

Table 4. Timer 2 Generated Commonly Used

Baud Rates

Baud Rate Timer 2

12-clock

mode

6-clock

mode

Osc Freq

RCAP2H RCAP2L

375 k 750 k 12 MHz FF FF

9.6 k 19.2 k 12 MHz FF D9

4.8 k 9.6 k 12 MHz FF B2

2.4 k 4.8 k 12 MHz FF 64

1.2 k 2.4 k 12 MHz FE C8 300 600 12 MHz FB 1E 110 220 12 MHz F2 AF 300 600 6 MHz FD 8F 110 220 6 MHz F9 57

Baud Rate Generator Mode

Bits TCLK and/or RCLK in T2CON (Table 4) allow the serial port transmit and receive baud rates to be derived from either Timer 1 or Timer 2. When TCLK= 0, Timer 1 is used as the serial port transmit baud rate generator . When TCLK= 1, Timer 2 is used as the serial port transmit baud rate generator. RCLK has the same effect for the serial port receive baud rate. With these two bits, the serial port can have different receive and transmit baud rates – one generated by Timer 1, the other by Timer 2.

Figure 11 shows the Timer 2 in baud rate generation mode. The baud rate generation mode is like the auto-reload mode,in that a rollover in TH2 causes the Timer 2 registers to be reloaded with the 16-bit value in registers RCAP2H and RCAP2L, which are preset by software.

Timer 2

Interrupt

SU01629

The baud rates in modes 1 and 3 are determined by Timer 2’s overflow rate given below:

Modes 1 and 3 Baud Rates +

Timer 2 Overflow Rate

The timer can be configured for either “timer” or “counter” operation. In many applications, it is configured for “timer” operation (C/T Timer operation is different for Timer 2 when it is being used as a baud rate generator.

Usually, as a timer it would increment every machine cycle (i.e.,

/6 the oscillator frequency in 6-clock mode, 1/12 the oscillator frequency in 12-clock mode). As a baud rate generator, it increments at the oscillator frequency in 6-clock mode (

OSC

12-clock mode). Thus the baud rate formula is as follows:

Modes 1 and 3 Baud Rates =

Oscillator Frequency

[n* [65536 * (RCAP2H, RCAP2L)]]

* n = 16 in 6-clock mode

32 in 12-clock mode

Where: (RCAP2H, RCAP2L)= The content of RCAP2H and RCAP2L taken as a 16-bit unsigned integer.

The Timer 2 as a baud rate generator mode shown in Figure 11, is valid only if RCLK and/or TCLK = 1 in T2CON register. Note that a rollover in TH2 does not set TF2, and will not generate an interrupt. Thus, the Timer 2 interrupt does not have to be disabled when Timer 2 is in the baud rate generator mode. Also if the EXEN2 (T2 external enable flag) is set, a 1-to-0 transition in T2EX (Timer/counter 2 trigger input) will set EXF2 (T2 external flag) but will not cause a reload from (RCAP2H, RCAP2L) to (TH2,TL2). Therefore when Timer 2 is in use as a baud rate generator, T2EX can be used as an additional external interrupt, if needed.

2=0).

/2 in

2002 Jul 18

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

When Timer 2 is in the baud rate generator mode, one should not try to read or write TH2 and TL2. As a baud rate generator, T imer 2 is incremented every state time (osc/2) or asynchronously from pin T2; under these conditions, a read or write of TH2 or TL2 may not be accurate. The RCAP2 registers may be read, but should not be written to, because a write might overlap a reload and cause write and/or reload errors. The timer should be turned off (clear TR2) before accessing the Timer 2 or RCAP2 registers.

Table 4 shows commonly used baud rates and how they can be obtained from Timer 2.

Summary of Baud Rate Equations

Timer 2 is in baud rate generating mode. If Timer 2 is being clocked through pin T2 (P1.0) the baud rate is:

Baud Rate +

Timer 2 Overflow Rate

If Timer 2 is being clocked internally, the baud rate is:

Baud Rate +

Where f

OSC

To obtain the reload value for RCAP2H and RCAP2L, the above equation can be rewritten as:

RCAP2H,RCAP2L + 65536 *

[n* [65536 * (RCAP2H, RCAP2L)]]

* n = 16 in 6-clock mode

= Oscillator Frequency

OSC

32 in 12-clock mode

n* Baud Rate

Timer/Counter 2 Set-up

Except for the baud rate generator mode, the values given for T2CON

do not include the setting of the TR2 bit. Therefore, bit TR2 must be set, separately, to turn the timer on. see Table 5 for set-up of Timer 2 as a timer. Also see Table 6 for set-up of Timer 2 as a counter.

Table 5. Timer 2 as a Timer

T2CON

MODE

16-bit Auto-Reload 00H 08H 16-bit Capture 01H 09H Baud rate generator receive and transmit same baud rate 34H 36H Receive only 24H 26H Transmit only 14H 16H

INTERNAL CONTROL

(Note 1)

EXTERNAL CONTROL

OSC

(Note 2)

Table 6. Timer 2 as a Counter

TMOD

MODE

16-bit 02H 0AH Auto-Reload 03H 0BH

NOTES:

1. Capture/reload occurs only on timer/counter overflow.

2. Capture/reload occurs on timer/counter overflow and a 1-to-0 transition on T2EX (P1.1) pin except when Timer 2 is used in the baud rate generator mode.

INTERNAL CONTROL

(Note 1)

EXTERNAL CONTROL

(Note 2)

2002 Jul 18

Philips Semiconductors Preliminary data

P89C51RA2/RB2/RC2/RD2xx80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

FULL-DUPLEX ENHANCED UART Standard UART operation

The serial port is full duplex, meaning it can transmit and receive simultaneously. It is also receive-buffered, meaning it can commence reception of a second byte before a previously received byte has been read from the register. (However, if the first byte still hasn’t been read by the time reception of the second byte is complete, one of the bytes will be lost.) The serial port receive and transmit registers are both accessed at Special Function Register SBUF. Writing to SBUF loads the transmit register, and reading SBUF accesses a physically separate receive register.

The serial port can operate in 4 modes: Mode 0: Serial data enters and exits through RxD. TxD outputs

the shift clock. 8 bits are transmitted/received (LSB first). The baud rate is fixed at 1/12 the oscillator frequency in 12-clock mode or 1/6 the oscillator frequency in 6-clock mode.

Mode 1: 10 bits are transmitted (through TxD) or received

(through RxD): a start bit (0), 8 data bits (LSB first), and a stop bit (1). On receive, the stop bit goes into RB8 in Special Function Register SCON. The baud rate is variable.

Mode 2: 1 1 bits are transmitted (through TxD) or received

(through RxD): start bit (0), 8 data bits (LSB first), a programmable 9th data bit, and a stop bit (1). On Transmit, the 9th data bit (TB8 in SCON) can be assigned the value of 0 or 1. Or, for example, the parity bit (P, in the PSW) could be moved into TB8. On receive, the 9th data bit goes into RB8 in Special Function Register SCON, while the stop bit is ignored. The baud rate is programmable to either 1/32 or 1/64 the oscillator frequency in 12-clock mode or 1/16 or 1/32 the oscillator frequency in 6-clock mode.

Mode 3: 1 1 bits are transmitted (through TxD) or received

(through RxD): a start bit (0), 8 data bits (LSB first), a programmable 9th data bit, and a stop bit (1). In fact, Mode 3 is the same as Mode 2 in all respects except baud rate. The baud rate in Mode 3 is variable.

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

Multiprocessor Communications

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

When the master processor wants to transmit a block of data to one of several slaves, it first sends out an address byte which identifies the target slave. An address byte differs from a data byte in that the 9th bit is 1 in an address byte and 0 in a data byte. With SM2 = 1, no slave will be interrupted by a data byte. An address byte, however, will interrupt all slaves, so that each slave can examine the received byte and see if it is being addressed. The addressed slave will clear its SM2 bit and prepare to receive the data bytes that will be coming.

The slaves that weren’t being addressed leave their SM2s set and go on about their business, ignoring the coming data bytes.

SM2 has no effect in Mode 0, and in Mode 1 can be used to check the validity of the stop bit. In a Mode 1 reception, if SM2 = 1, the receive interrupt will not be activated unless a valid stop bit is received.

Serial Port Control Register

The serial port control and status register is the Special Function Register SCON, shown in Figure 12. This register contains not only the mode selection bits, but also the 9th data bit for transmit and receive (TB8 and RB8), and the serial port interrupt bits (TI and RI).

Baud Rates

The baud rate in Mode 0 is fixed: Mode 0 Baud Rate = Oscillator Frequency / 12 (12-clock mode) or / 6 (6-clock mode). The baud rate in Mode 2 depends on the value of bit SMOD in Special Function Register PCON. If SMOD = 0 (which is the value on reset), and the port pins in 12-clock mode, the baud rate is 1/64 the oscillator frequency . If SMOD = 1, the baud rate is 1/32 the oscillator frequency. In 6-clock mode, the baud rate is 1/32 or 1/16 the oscillator frequency, respectively.

Mode 2 Baud Rate =

SMOD

 (Oscillator Frequency)

Where:

n = 64 in 12-clock mode, 32 in 6-clock mode

The baud rates in Modes 1 and 3 are determined by the Timer 1 or Timer 2 overflow rate.

Using Timer 1 to Generate Baud Rates

When Timer 1 is used as the baud rate generator (T2CON.RCLK = 0, T2CON.TCLK = 0), the baud rates in Modes 1 and 3 are determined by the Timer 1 overflow rate and the value of SMOD as follows:

Mode 1, 3 Baud Rate =

SMOD

 (Timer 1 Overflow Rate)

Where:

n = 32 in 12-clock mode, 16 in 6-clock mode

The Timer 1 interrupt should be disabled in this application. The Timer itself can be configured for either “timer” or “counter” operation, and in any of its 3 running modes. In the most typical applications, it is configured for “timer” operation, in the auto-reload mode (high nibble of TMOD = 0010B). In that case the baud rate is given by the formula:

Mode 1, 3 Baud Rate =

SMOD

Where:

n = 32 in 12-clock mode, 16 in 6-clock mode

One can achieve very low baud rates with Timer 1 by leaving the Timer 1 interrupt enabled, and configuring the Timer to run as a 16-bit timer (high nibble of TMOD = 0001B), and using the Timer 1 interrupt to do a 16-bit software reload. Figure 13 lists various commonly used baud rates and how they can be obtained from Timer 1.

Oscillator Frequency



12  [256–(TH1)]

2002 Jul 18

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Philips P89C51RA2BA-01, P89C51RA2BBD-01, P89C51RB2BA-01, P89C51RB2BBD-01, P89C51RC2BN-01 User Manual

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