Datasheet
Table 18-6. Port C Pins Alternate Functions
Port Pin Alternate Function
PC6 RESET (Reset pin)
PCINT14 (Pin Change Interrupt 14)
PC5 ADC5 (ADC Input Channel 5)
SCL (2-wire Serial Bus Clock Line)
PCINT13 (Pin Change Interrupt 13)
PC4 ADC4 (ADC Input Channel 4)
SDA (2-wire Serial Bus Data Input/Output Line)
PCINT12 (Pin Change Interrupt 12)
PC3 ADC3 (ADC Input Channel 3)
PCINT11 (Pin Change Interrupt 11)
PC2 ADC2 (ADC Input Channel 2)
PCINT10 (Pin Change Interrupt 10)
PC1 ADC1 (ADC Input Channel 1)
PCINT9 (Pin Change Interrupt 9)
PC0 ADC0 (ADC Input Channel 0)
PCINT8 (Pin Change Interrupt 8)
The alternate pin configuration is as follows:
• RESET/PCINT14 – Port C, Bit 6
– RESET: Reset pin. When the RSTDISBL Fuse is programmed, this pin functions as a normal
I/O pin, and the part will have to rely on Power-on Reset and Brown-out Reset as its reset
sources. When the RSTDISBL Fuse is unprogrammed, the reset circuitry is connected to the
pin, and the pin can not be used as an I/O pin.
– PCINT14: Pin Change Interrupt source 14. The PC6 pin can serve as an external interrupt
source.
If PC6 is used as a reset pin, DDC6, PORTC6 and PINC6 will all read 0.
• SCL/ADC5/PCINT13 – Port C, Bit 5
– SCL: 2-wire Serial Interface Clock. When the TWEN bit in TWCR is set (one) to enable the 2-
wire Serial Interface, pin PC5 is disconnected from the port and becomes the Serial Clock I/O
pin for the 2-wire Serial Interface. In this mode, there is a spike filter on the pin to suppress
spikes shorter than 50 ns on the input signal, and the pin is driven by an open drain driver
with slew-rate limitation.
– PCINT13: Pin Change Interrupt source 13. The PC5 pin can serve as an external interrupt
source.
– PC5 can also be used as ADC input Channel 5. The ADC input channel 5 uses digital power.
• SDA/ADC4/PCINT12 – Port C, Bit 4
– SDA: 2-wire Serial Interface Data. When the TWEN bit in TWCR is set (one) to enable the 2-
wire Serial Interface, pin PC4 is disconnected from the port and becomes the Serial Data I/O
pin for the 2-wire Serial Interface. In this mode, there is a spike filter on the pin to suppress
spikes shorter than 50 ns on the input signal, and the pin is driven by an open drain driver
with slew-rate limitation.
ATmega48PA/88PA/168PA
I/O-Ports
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40002011A-page 119