55
7598H–AVR–07/09
ATtiny25/45/85
• Port B, Bit 4- XTAL2/CLKO/ADC2/OC1B/PCINT4
XTAL2: Chip Clock Oscillator pin 2. Used as clock pin for all chip clock sources except internal
calibrateble RC Oscillator and external clock. When used as a clock pin, the pin can not be used
as an I/O pin. When using internal calibratable RC Oscillator or External clock as a Chip clock
sources, PB4 serves as an ordinary I/O pin.
CLKO: The devided system clock can be output on the pin PB4. The divided system clock will be
output if the CKOUT Fuse is programmed, regardless of the PORTB4 and DDB4 settings. It will
also be output during reset.
ADC2: Analog to Digital Converter, Channel 2
.
OC1B: Output Compare Match output: The PB4 pin can serve as an external output for the
Timer/Counter1 Compare Match B when configured as an output (DDB4 set). The OC1B pin is
also the output pin for the PWM mode timer function.
PCINT4: Pin Change Interrupt source 4.
• Port B, Bit 3 - XTAL1/ADC3/OC1B/PCINT3
XTAL1: Chip Clock Oscillator pin 1. Used for all chip clock sources except internal calibrateble
RC oscillator. When used as a clock pin, the pin can not be used as an I/O pin.
ADC3: Analog to Digital Converter, Channel 3
.
OC1B: Inverted Output Compare Match output: The PB3 pin can serve as an external output for
the Timer/Counter1 Compare Match B when configured as an output (DDB3 set). The OC1B pin
is also the inverted output pin for the PWM mode timer function.
PCINT3: Pin Change Interrupt source 3.
• Port B, Bit 2 - SCK/ADC1/T0/USCK/SCL/INT0/PCINT2
SCK: Master Clock output, Slave Clock input pin for SPI channel. When the SPI is enabled as a
Slave, this pin is configured as an input regardless of the setting of DDB2. When the SPI is
enabled as a Master, the data direction of this pin is controlled by DDPB2. When the pin is
forced by the SPI to be an input, the pull-up can still be controlled by the PORTB2 bit.
ADC1: Analog to Digital Converter, Channel 1
.
T0: Timer/Counter0 counter source.
USCK: Three-wire mode Universal Serial Interface Clock.
SCL: Two-wire mode Serial Clock for USI Two-wire mode.
INT0: External Interrupt source 0.
PCINT2: Pin Change Interrupt source 2.
• Port B, Bit 1 - MISO/AIN1/OC0B/OC1A/DO/PCINT1
MISO: Master Data input, Slave Data output pin for SPI channel. When the SPI is enabled as a
Master, this pin is configured as an input regardless of the setting of DDB1. When the SPI is
enabled as a Slave, the data direction of this pin is controlled by DDB1. When the pin is forced
by the SPI to be an input, the pull-up can still be controlled by the PORTB1 bit.
AIN1: Analog Comparator Negative Input. Configure the port pin as input with the internal pull-up
switched off to avoid the digital port function from interfering with the function of the Analog
Comparator.