Rainbow Electronics ATtiny12 - Manual (Page 43)

43
ATtiny11/12
1006C–09/01
Alternate Functions of Port B All port B pins are connected to a pin change detector that can trigger the pin change
interrupt. See “Pin Change Interrupt” on page 27 for details. In addition, Port B has the
following alternate functions:
• RESET - Port B, Bit 5
When the RSTDISBL fuse is unprogrammed, this pin serves as external reset. When
the RSTDISBL fuse is programmed, this pin is a general input pin. In ATtiny12, it is also
an open-drain output pin.
• XTAL2 - Port B, Bit 4
XTAL2, oscillator output. When this pin is not used for clock purposes, it is a general I/O
pin. Refer to section “Pin Descriptions” on page 5 for details.
• XTAL1 - Port B, Bit 3
XTAL1, oscillator or clock input. When this pin is not used for clock purposes, it is a gen-
eral I/O pin. Refer to section “Pin Descriptions” on page 5 for details.
• T0/SCK - Port B, Bit 2
This pin can serve as the external counter clock input. See the timer/counter description
for further details. If external timer/counter clocking is selected, activity on this pin will
clock the counter even if it is configured as an output. In ATtiny12 and serial program-
ming mode, this pin serves as the serial clock input, SCK.
• INT0/AIN1/MISO - Port B, Bit 1
This pin can serve as the external interrupt0 input. See the interrupt description for
details on how to enable this interrupt. Note that activity on this pin will trigger the inter-
rupt even if the pin is configured as an output. This pin also serves as the negative input
of the on-chip Analog Comparator. In ATtiny12 and serial programming mode, this pin
serves as the serial data input, MISO.
• AIN0/MOSI - Port B, Bit 0
This pin also serves as the positive input of the on-chip Analog Comparator. In ATtiny12
and serial programming mode, this pin serves as the serial data output, MOSI.
During Power-down Mode, the schmitt triggers of the digital inputs are disconnected on
the Analog Comparator input pins. This allows an analog voltage close to V
CC
/2 to be
present during power-down without causing excessive power consumption.