AT/T89C51CC02
Pin Description
Pin Name
Type
Description
VSS
VCC
VAREF
VAVCC
VAGND
P1.0:7
GND
Circuit ground
Supply Voltage
Reference Voltage for ADC (input)
Supply Voltage for ADC
Reference Ground for ADC (internaly connected with the VSS)
I/O
Port 1:
Is an 8-bit bi-directional I/O port with internal pull-ups. Port 1 pins can be used for digital input/output or as
analog inputs for the Analog Digital Converter (ADC). Port 1 pins that have 1’s written to them are pulled
high by the internal pull-up transistors and can be used as inputs in this state. As inputs, Port 1 pins that
are being pulled low externally will be the source of current (I
IL
, See section ’Electrical Characteristic’)
because of the internal pull-ups. Port 1 pins are assigned to be used as analog inputs via the ADCCF
register (in this case the internal pull-ups are disconnected).
As a secondary digital function, port 1 contains the Timer 2 external trigger and clock input; the PCA
external clock input and the PCA module I/O.
P1.0/AN0/T2
Analog input channel 0,
External clock input for Timer/counter2.
P1.1/AN1/T2EX
Analog input channel 1,
Trigger input for Timer/counter2.
P1.2/AN2/ECI
Analog input channel 2,
PCA external clock input.
P1.3/AN3/CEX0
Analog input channel 3,
PCA module 0 Entry of input/PWM output.
P1.4/AN4/CEX1
Analog input channel 4,
PCA module 1 Entry of input/PWM output.
P1.5/AN5
Analog input channel 5,
P1.6/AN6
Analog input channel 6,
P1.7/AN7
Analog input channel 7,
It can drive CMOS inputs without external pull-ups.
Port 2:
Is an 2-bit bi-directional I/O port with internal pull-ups. Port 2 pins that have 1’s written to them are pulled
high by the internal pull-ups and can be used as inputs in this state. As inputs, Port 2 pins that are being
pulled low externally will be a source of current (IIL, on the datasheet) because of the internal pull-ups.
In the T89C51CC02 Port 2 can sink or source 5mA. It can drive CMOS inputs without external pull-ups.
P2.0:1
I/O
5
4126L–CAN–01/08
ATMEL [ ATMEL CORPORATION ]
