Datasheet

ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller VQFP 44 (10x10) 8-Bit 40 MHz I/O number 32

AT89C51RB2/RC2

4180E–8051–10/06

Table 12. Pin Description for 40 - 44 Pin Packages

Mnemonic

Pin Number

Type Name and FunctionDIL 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, bi-directional 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 V

or V

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 bi-directional 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 AT89C51RB2/RC2 Port 1 include:

1 2 40 I/O P1.0: Input/Output

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

2 3 41 I/O P1.1: Input/Output

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

I SS

: SPI Slave Select

3 4 42 I/O P1.2: Input/Output

I ECI: External Clock for the PCA

4 5 43 I/O P1.3: Input/Output

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

5 6 44 I/O P1.4: Input/Output

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

6 7 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.

7 8 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

8 9 3 I/O P1.7: Input/Output: