Alternate Functions of Port B

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

Table 1. Port B Pins Alternate Functions
Port Pin	Alternate Functions
PB[0]	ADC4: ADC Input Channel 4 PCINT8: Pin Change Interrupt source 8
PB[1]	ADC5: ADC Input Channel 5 OC0A: Timer/Counter0 Compare Match A Output (default location) PCINT9: Pin Change Interrupt source 9 INT0: External Interrupt 0 Source CLKO: System Clock Output
PB[2]	ADC6: ADC Input Channel 6 ICP0: Timer/Counter0 Input Capture Input (default location) TxD0: USART Output PCINT10: Pin Change Interrupt source 10
PB[3]	ACO: AC Output ADC7: ADC Input Channel 7 T0: Timer/Counter0 Clock Source (alternative location) RxD0: USART Input PCINT11: Pin Change Interrupt source 11

The alternate pin configuration is as follows:

PB[0] – ADC4/PCINT8
- ADC4: Analog to Digital Converter, Channel 4.
- PCINT8: Pin Change Interrupt source 8. The PB[0] pin can serve as an external interrupt source for pin change interrupt 1.
PB[1] – ADC5/OC0A/PCINT9/INT0/CLKO
- ADC5: Analog to Digital Converter, Channel 5
- OC0A: Output Compare Match output. The PB[1] pin can serve as an external output for the Timer/Counter0 Compare Match A. The PB[1] pin has to be configured as an output (DDB0 set (one)) to serve this function. The OC0A pin is also the output pin for the PWM mode timer function.
- PCINT9: Pin Change Interrupt source 9. The PB[1] pin can serve as an external interrupt source for pin change interrupt 1.
- INT0: External Interrupt Request 0.
- CLKO: System Clock Output. The system clock can be output on pin PB[1]. The system clock will be output if CKOUT bit is programmed, regardless of the PORTB2 and DDB2 settings.
PB[2] – ADC6/ICP0/TxD0/PCINT10
- ADC6: Analog to Digital Converter, Channel 6.
- ICP0: Input Capture Pin. The PB[2] pin can act as an Input Capture pin for Timer/Counter0.
- PCINT10: Pin Change Interrupt source 10. The PB[2] pin can serve as an external interrupt source for pin change interrupt 1.
- TxD0: USART Output
PB[3] – ACO/ADC7/T0/RXD0/PCINT3/RXD0
- ACO: AC Output
- ADC7: Analog to Digital Converter, Channel 7.
- T0: Timer/Counter0 counter source.
- PCINT11: Pin Change Interrupt source 11. The PB[3] pin can serve as an external interrupt source for pin change interrupt 1.
- RXD0: USART input

The following tables relate the alternate functions of Port B to the overriding signals shown in the figure of Alternate Port Functions.

Table 2. Overriding Signals for Alternate Functions in PB[3:2]
Signal  Name	PB3/ADC7/ACO/RxD0/T0/PCINT11	PB2/ADC6/TxD0/ICP0/PCINT10
PUOE	ACOE	TxEN0
PUOV	0	0
DDOE	RxEN0 + (RxEN0 • ACOE)	TxEN0
DDOV	ACOE	TxEN0
PVOE	ACOE	TxEN0
PVOV	ACO • ACOE	TxEN0• TXD0_OUT
PTOE	0	0
DIEOE	(PCINT11 • PCIE1) + ADC7D	(PCINT10 • PCIE1) + ADC6D
DIEOV	PCINT11• PCIE1	PCINT10 • PCIE1
DI	RxD0/T0/PCINT11 Input	ICP0/PCINT10 input
AIO	ADC7/ AC Output	ADC6

Table 3. Overriding Signals for Alternate Functions in PB[1:0]
Signal  Name	PB1/ADC5/INT0/XCK0/CLKO/OC0A/PCINT9	PB0/ADC4/PCINT8
PUOE	CKOUT⁽¹⁾	0
PUOV	0	0
DDOE	CKOUT⁽¹⁾+ (OC0A Enable • REMAP) + XCK0_MASTER	0
DDOV	CLKO + (CKOUT • OC0A Enable • REMAP • OC0A) + (CKOUT • (OC0A Enable + REMAP) • XCK0_MASTER • XCK0_OUT)	0
PVOE	CKOUT⁽¹⁾	0
PVOV	(system clock)	0
PTOE	0	0
DIEOE	(PCINT9 • PCIE1) + ADC5D + INT0	(PCINT8 • PCIE1) + ADC4D
DIEOV	(PCINT9 • PCIE1) + INT0	(PCINT8 • PCIE1)
DI	INT0/PCINT1 Input	PCINT8 Input
AIO	ADC5	ADC4

Note:

1.CKOUT is 1 when the configuration bit is “0” (Programmed).

8-bit AVR Microcontroller

Alternate Functions of Port B