8-bit AVR Microcontrollers

Alternate Functions of Port C

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

Table 1. Port C Pins Alternate Functions
Port Pin Alternate Function
PC6

RESET (Reset pin)

PCINT14 (Pin Change Interrupt 14)

PC5

ADC5 (ADC Input Channel 5)

SCL0 (two-wire Serial Bus Clock Line)

PCINT13 (Pin Change Interrupt 13)

PC4

ADC4 (ADC Input Channel 4)

SDA0 (two-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

SCK1 (SPI1 Master Clock output)
ADC1 (ADC Input Channel 1)

PCINT9 (Pin Change Interrupt 9)

PC0

MISO1
ADC0 (ADC Input Channel 0)

PCINT8 (Pin Change Interrupt 8)

The alternate pin configuration is as follows:

If PC6 is used as a reset pin, DDC6, PORTC6 and PINC6 will all read 0.

The tables below relate the alternate functions of Port C to the overriding signals shown in Figure 1.

Table 2. Overriding Signals for Alternate Functions in PC6...PC4(1)
Signal
Name PC6/RESET/PCINT14 PC5/SCL0/ADC5/PCINT13 PC4/SDA0/ADC4/PCINT12
PUOE RSTDISBL TWEN0 TWEN0
PUOV 1 PORTC5 • PUD PORTC4 • PUD
DDOE RSTDISBL TWEN0 TWEN0
DDOV 0 SCL_OUT0 SDA_OUT0
PVOE 0 TWEN0 TWEN0
PVOV 0 0 0
DIEOE RSTDISBL + PCINT14 • PCIE1 PCINT13 • PCIE1 + ADC5D PCINT12 • PCIE1 + ADC4D
DIEOV RSTDISBL PCINT13 • PCIE1 PCINT12 • PCIE1
DI PCINT14 INPUT PCINT13 INPUT PCINT12 INPUT
AIO RESET INPUT ADC5 INPUT / SCL0 INPUT ADC4 INPUT / SDA INPUT0
Note: 1. When enabled, the two-wire Serial Interface enables slew-rate controls on the output pins PC4 and PC5. This is not shown in the figure. In addition, spike filters are connected between the AIO outputs shown in the port figure and the digital logic of the TWI module.
Table 3. Overriding Signals for Alternate Functions in PC3...PC0
Signal
Name PC3/ADC3/
PCINT11 PC2/ADC2/
PCINT10 PC1/ADC1/SCK1/
PCINT9 PC0/ADC0/MISO1/
PCINT8
PUOE 0 0 SPE1 • MSTR SPE1 • MSTR
PUOV 0 0 PORTC1 • PUD PORTC0 • PUD
DDOE 0 0 SPE1 • MSTR SPE1 • MSTR
DDOV 0 0 0 0
PVOE 0 0 SPE1 • MSTR SPE1 • MSTR
PVOV 0 0 SCK1 OUTPUT SPI1 SLAVE INPUT
DIEOE PCINT11 • PCIE1 +
ADC3D PCINT10 • PCIE1 +
ADC2D PCINT9 • PCIE1 +
ADC1D PCINT8 • PCIE1 +
ADC0D
DIEOV PCINT11 • PCIE1 PCINT10 • PCIE1 PCINT9 • PCIE1 PCINT8 • PCIE1
DI PCINT11 INPUT PCINT10 INPUT

PCINT9 INPUT
SCK1 INPUT

PCINT8 INPUT
SPI1 MASTER INPUT

AIO ADC3 INPUT ADC2 INPUT ADC1 INPUT ADC0 INPUT