63
ATmega8535(L)
2502K–AVR–10/06
TOSC2, Timer Oscillator pin 2: When the AS2 bit in ASSR is set (one) to enable asyn-
chronous clocking of Timer/Counter2, pin PC7 is disconnected from the port, and
becomes the inverting output of the Oscillator amplifier. In this mode, a crystal Oscillator
is connected to this pin, and the pin can not be used as an I/O pin.
• TOSC1 – Port C, Bit 6
TOSC1, Timer Oscillator pin 1: When the AS2 bit in ASSR is set (one) to enable asyn-
chronous clocking of Timer/Counter2, pin PC6 is disconnected from the port, and
becomes the input of the inverting Oscillator amplifier. In this mode, a crystal Oscillator
is connected to this pin, and the pin can not be used as an I/O pin.
• SDA – Port C, Bit 1
SDA, Two-wire Serial Interface Data: When the TWEN bit in TWCR is set (one) to
enable the Two-wire Serial Interface, pin PC1 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 suppress spikes shorter than 50 ns on the input signal, and the
pin is driven by an open drain driver with slew-rate limitation. When this pin is used by
the Two-wire Serial Interface, the pull-up can still be controlled by the PORTC1 bit.
• SCL – Port C, Bit 0
SCL, Two-wire Serial Interface Clock: When the TWEN bit in TWCR is set (one) to
enable the Two-wire Serial Interface, pin PC0 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 suppress spikes shorter than 50 ns on the input signal, and the
pin is driven by an open drain driver with slew-rate limitation. When this pin is used by
the Two-wire Serial Interface, the pull-up can still be controlled by the PORTC0 bit.
Table 30 and Table 31 relate the alternate functions of Port C to the overriding signals
shown in Figure 26 on page 57.
Table 30. Overriding Signals for Alternate Functions in PC7..PC6
Signal Name PC7/TOSC2 PC6/TOSC1
PUOE AS2 AS2
PUOV 0 0
DDOE AS2 AS2
DDOV 0 0
PVOE 0 0
PVOV 0 0
DIEOE AS2 AS2
DIEOV 0 0
DI – –
AIO T/C2 OSC OUTPUT T/C2 OSC INPUT
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