AT89C51IC2-SLSCM datasheet(11/146 Pages) ATMEL

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AT89C51IC2

4301A–8051–01/04

Table 13. Pin Description for 40/44 Pin Packages

Mnemonic

Pin Number

Type

Name and Function

PLCC44

VQFP44 1.4

VSS

Ground: 0V reference

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

them float and can be used as high impedance inputs. Port 0 must be polarized to V

or VSS in order to prevent any parasitic current consumption. Port 0 is also the multi-

plexed 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 dur-

ing 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 AT89C51IC2 Port 1 include:

240

I/O

P1.0: Input/Output

I/O

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

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

341

I/O

P1.1: Input/Output

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

SS: SPI Slave Select

442

I/O

P1.2: Input/Output

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

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

AT89C51IC2-SLSCM Datasheet(PDF) 11 Page - ATMEL Corporation

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