Datasheet

63
2586N–AVR–04/11
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/CLKI/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.
• CLKI: Clock Input from an external clock source, see “External Clock” on page 26.
• 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.
• OC0B: Output Compare Match output. The PB1 pin can serve as an external output for the
Timer/Counter0 Compare Match B. The PB1 pin has to be configured as an output (DDB1