6

T89C51IC2

Rev. C – 3-Dec-01

Table 1. Pin Description for 40/44 pin packages

Mnemonic

Pin Number

Type

Name and Function

PLCC44

VQFP44 1.4

22

16

I

Ground: 0V reference

44

38

I

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

operation

P0.0-P0.7

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

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 EPROM programming. External pull-ups are required

during program verification during which P0 outputs the code bytes.

P1.0-P1.7

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 T89C51IC2 Port 1 include:

240

I/O

P1.0: Input / Output

I/O

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

I

XTALB1 (P1.0): Sub Clock input to the inverting oscillator amplifier

341

I/O

P1.1: Input / Output

I

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

I

SS: SPI Slave Select

442

I/O

P1.2: Input / Output

I

ECI: External Clock for the PCA

543

I/O

P1.3: Input / Output

I/O

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

644

I/O

P1.4: Input / Output

I/O

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

71

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

is in slave mode, MISO outputs data to the master controller.

82

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

93

I/O

P1.7: Input / Output: