ATmega8(L)
Alternate Functions of
Port C
The Port C pins with alternate functions are shown in
Table 25.
Port C Pins Alternate Functions
Port Pin
PC6
PC5
PC4
PC3
PC2
PC1
PC0
Alternate Function
RESET (Reset pin)
ADC5 (ADC Input Channel 5)
SCL (Two-wire Serial Bus Clock Line)
ADC4 (ADC Input Channel 4)
SDA (Two-wire Serial Bus Data Input/Output Line)
ADC3 (ADC Input Channel 3)
ADC2 (ADC Input Channel 2)
ADC1 (ADC Input Channel 1)
ADC0 (ADC Input Channel 0)
The alternate pin configuration is as follows:
• RESET – 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.
If PC6 is used as a reset pin, DDC6, PORTC6 and PINC6 will all read 0.
• SCL/ADC5 – Port C, Bit 5
SCL, Two-wire Serial Interface Clock: When the TWEN bit in TWCR is set (one) to enable the
Two-wire Serial Interface, pin PC5 is disconnected from the port and becomes the Serial Clock
I/O pin for the Two-wire Serial Interface. In this mode, there is a spike filter on the pin to sup-
press spikes shorter than 50 ns on the input signal, and the pin is driven by an open drain driver
with slew-rate limitation.
PC5 can also be used as ADC input Channel 5. Note that ADC input channel 5 uses digital
power.
• SDA/ADC4 – Port C, Bit 4
SDA, Two-wire Serial Interface Data: When the TWEN bit in TWCR is set (one) to enable the
Two-wire Serial Interface, pin PC4 is disconnected from the port and becomes the Serial Data
I/O pin for the Two-wire Serial Interface. In this mode, there is a spike filter on the pin to sup-
press spikes shorter than 50 ns on the input signal, and the pin is driven by an open drain driver
with slew-rate limitation.
PC4 can also be used as ADC input Channel 4. Note that ADC input channel 4 uses digital
power.
• ADC3 – Port C, Bit 3
PC3 can also be used as ADC input Channel 3. Note that ADC input channel 3 uses analog
power.
• ADC2 – Port C, Bit 2
PC2 can also be used as ADC input Channel 2. Note that ADC input channel 2 uses analog
power.
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2486AA–AVR–02/2013
ATMEL [ ATMEL CORPORATION ]
