Alternate Functions of Port A

The Port A pins with alternate functions are shown in the table below:

Table 1. Port A Pins Alternate Functions
Port Pin	Alternate Functions
PA7	ADC7 (ADC input channel 7) PCINT7 (Pin Change Interrupt 7)
PA6	ADC6 (ADC input channel 6) PCINT6 (Pin Change Interrupt 6)
PA5	ADC5 (ADC input channel 5) PCINT5 (Pin Change Interrupt 5)
PA4	ADC4 (ADC input channel 4) PCINT4 (Pin Change Interrupt 4)
PA3	ADC3 (ADC input channel 3) PCINT3 (Pin Change Interrupt 3)
PA2	ADC2 (ADC input channel 2) PCINT2 (Pin Change Interrupt 2)
PA1	ADC1 (ADC input channel 1) PCINT1 (Pin Change Interrupt 1)
PA0	ADC0 (ADC input channel 0) PCINT0 (Pin Change Interrupt 0)

The alternate pin configuration is as follows:

ADC[7:0]/PCINT[7:0] – Port A, Bit [7:0]
- ADC[7:0]: Analog to Digital Converter Channels [7:0].
- PCINT[7:0]: Pin Change Interrupt source [7:0]. The PA[7:0] pins can serve as external interrupt sources.

Table 2. Overriding Signals for Alternate Functions in PA7...PA4
Signal Name	PA7/ADC7/ PCINT7	PA6/ADC6/ PCINT6	PA5/ADC5/ PCINT5	PA4/ADC4/ PCINT4
PUOE	0	0	0	0
PUOV	0	0	0	0
DDOE	0	0	0	0
DDOV	0	0	0	0
PVOE	0	0	0	0
PVOV	0	0	0	0
DIEOE	PCINT7 • PCIE0 + ADC7D	PCINT6 • PCIE0 + ADC6D	PCINT5 • PCIE0 + ADC5D	PCINT4 • PCIE0 + ADC4D
DIEOV	PCINT7 • PCIE0	PCINT6 • PCIE0	PCINT5 • PCIE0	PCINT4 • PCIE0
DI	PCINT7 INPUT	PCINT6 INPUT	PCINT5 INPUT	PCINT4 INPUT
AIO	ADC7 INPUT	ADC6 INPUT	ADC5 INPUT	ADC4 INPUT

Table 3. Overriding Signals for Alternate Functions in PA3...PA0
Signal Name	PA3/ADC3/ PCINT3	PA2/ADC2/ PCINT2	PA1/ADC1/ PCINT1	PA0/ADC0/ PCINT0
PUOE	0	0	0	0
PUOV	0	0	0	0
DDOE	0	0	0	0
DDOV	0	0	0	0
PVOE	0	0	0	0
PVOV	0	0	0	0
DIEOE	PCINT3 • PCIE0 + ADC3D	PCINT2 • PCIE0 + ADC2D	PCINT1 • PCIE0 + ADC1D	PCINT0 • PCIE0 + ADC0D
DIEOV	PCINT3 • PCIE0	PCINT2 • PCIE0	PCINT1 • PCIE0	PCINT0 • PCIE0
DI	PCINT3 INPUT	PCINT2 INPUT	PCINT1 INPUT	PCINT0 INPUT
AIO	ADC3 INPUT	ADC2 INPUT	ADC1 INPUT	ADC0 INPUT