ATMEGA8_14 Datasheet, PDF (61/331 Pages) ATMEL Corporation – High-performance, Low-power Atmel

ATmega8(L)
Alternate Functions of The Port C pins with alternate functions are shown in Table 25.
Port C
Table 25. Port C Pins Alternate Functions
Port Pin
Alternate Function
PC6
RESET (Reset pin)
PC5
ADC5 (ADC Input Channel 5)
SCL (Two-wire Serial Bus Clock Line)
PC4
ADC4 (ADC Input Channel 4)
SDA (Two-wire Serial Bus Data Input/Output Line)
PC3
ADC3 (ADC Input Channel 3)
PC2
ADC2 (ADC Input Channel 2)
PC1
ADC1 (ADC Input Channel 1)
PC0
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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