6

Rev. B - 30-Mar-01

Preliminary

T89C51RB2/RC2

Table 3. Pin Description for 40/44 pin packages

Mnemonic

Pin Number

Type

Name and Function

DIL

LCC

VQFP44

1.4

20

22

16

I

Ground: 0V reference

40

44

38

I

Power Supply: This is the power supply voltage for normal, idle and

power-down operation

P0.0-P0.7

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 written to them float and can be used as high impedance inputs.

current consumption. Port 0 is also the multiplexed low-order address

and data bus during access to external program and data memory. In this

application, it uses strong internal pull-up when emitting 1s. Port 0 also

inputs the code bytes during FLASH programming. External pull-ups are

required during program verification during which P0 outputs the code

bytes.

P1.0-P1.7

1-8

2-9

40-44

1-3

I/O

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

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. Port 1 also receives the low-order address byte during memory

programming and verification.

Alternate functions for T89C51RB2/RC2 Port 1 include:

12

40

I/O

P1.0 : Input / Output

I/O

T2 (P1.0): Timer/Counter 2 external count input/Clockout

23

41

I/O

P1.1 : Input / Output

I

T2EX : Timer/Counter 2 Reload/Capture/Direction Control

I

SS : SPI Slave Select

34

42

I/O

P1.2 : Input / Output

I

ECI : External Clock for the PCA

45

43

I/O

P1.3: Input / Output

I/O

CEX0 : Capture/Compare External I/O for PCA module 0

56

44

I/O

P1.4 : Input / Output

I/O

CEX1 : Capture/Compare External I/O for PCA module 1

67

1

I/O

P1.5 : Input / Output

I/O

CEX2 : Capture/Compare External I/O for PCA module 2

I/O

MISO : SPI Master Input Slave Output line

When SPI is is in master mode , MISO receives data from the slave

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

controller.

78

2

I/O

P1.6 : Input / Output

I/O

CEX3 : Capture/Compare External I/O for PCA module 3

I/O

SCK : SPI Serial Clock

SCK outputs clock to the slave peripheral

89

3

I/O

P1.7 : Input / Output:

I/O

CEX4 : Capture/Compare External I/O for PCA module 4

I/O

MOSI : SPI Master Output Slave Input line

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

When SPI is in slave mode , MOSI receives data from the master

controller.

XTAL1

19

21

15

I

Crystal 1: Input to the inverting oscillator amplifier and input to the

internal clock generator circuits.

XTAL2

18

20

14

O

Crystal 2: Output from the inverting oscillator amplifier