Pin Description
Mnemonic
VSS
Type
Name and Function
I
I
Ground: 0V reference
Power Supply: 3.0V or 5.5V
VCC
P1.0 - P1.7
Port 1: Port 1 is an 8-bit programmable I/O port with internal pull-up
I/O
Alternate functions for Port 1 include:
I/O
I/O
MISO (P1.0): Master IN, Slave OUT of the SPI controller
MOSI (P1.1): Master OUT, Slave IN of the SPI controller
DIG2 (P1.2): Programmable as Output with Push-pull
ECI: External Clock for PCA
I/O
I/O
I/O
I/O
I/O
CEX0 (P1.3): Capture/Compare External I/O for PCA module 0
CEX1 (P1.4): Capture/Compare External I/O for PCA module 1
CEX2 (P1.5): Capture/Compare External I/O for PCA module 2
CEX3 (P1.6): Capture/Compare External I/O for PCA module 3
SS (P1.7): Slave select input of the SPI controller
I/O
CEX4: Capture/Compare External I/O for PCA module 3
XTAL1
I
Input to the inverting oscillator amplifier
Output from the inverting oscillator amplifier
RST: Negative Reset input
XTAL2
O
RST/VPP
A low on this pin for two machine cycles while the oscillator is running,
resets the device.
I
This pin will include a pull-down to reset the circuit if no external reset
level is applied.
VPP: High voltage input for OTP programming
P3.0 - P3.7
I/O
I/O
I/O
Port 3: Port 3 is a 8-bit programmable I/O port with internal pull-up.
P3.0: Programmable as Output with Push-pull.
P3.1: Programmable as Output with Push-pull.
DIG0 (P3.2): Programmable as Output with Push-pull.
INT0: External Interrupt 0
I/O
I/O
I/O
I/O
P3.3: Programmable as Output with Push-pull.
INT1: External Interrupt 1
DIG1 (P3.4): Programmable as Output with Push-pull.
T0: Timer 0 external Input
P3.5: Programmable as Output with Push-pull.
T1: Timer 1 external Input
I/O
I/O
I/O
SPICK (P3.6): Clock I/O of the SPI controller
P3.7: Programmable as Output with Push-pull.
P4.0-P4.2
Port 4: Port 4 is an 3-bit I/O port with internal pull-up
4
AT8xC5103
4134C–8051–09/04