T89C51RB2-3CSIM datasheet(6/117 Pages) ATMEL

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T89C51RB2/RC2

4105D–8051–10/06

Table 3. Pin Description for 40 - 44 Pin Packages

Mnemonic

Pin Number

Type

Name and Function

DIL

LCC

VQFP44 1.4

VSS

Ground: 0V reference

VCC

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. Port 0 must be

polarized to VCC or VSS in order to prevent any parasitic 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:

I/O

P1.0: Input / Output

I/O

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

I/O

P1.1: Input / Output

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

SS: SPI Slave Select

I/O

P1.2: Input / Output

ECI: External Clock for the PCA

I/O

P1.3: Input / Output

I/O

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

I/O

P1.4: Input / Output

I/O

CEX1: Capture/Compare External I/O for PCA module 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 in master mode, MISO receives data from the slave peripheral. When

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

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

I/O

P1.7: Input / Output:

T89C51RB2-3CSIM Datasheet(PDF) 6 Page - ATMEL Corporation

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