ATTINY87_14 Datasheet, PDF (74/261 Pages) ATMEL Corporation – 8-bit AVR Microcontroller with 8K/16K Bytes In-System

The alternate pin configuration is as follows:
• PCINT7/ADC7/AIN1/XREF/AREF – Port A, Bit7
PCINT7: pin change interrupt, source 7.
ADC7: analog to digital converter, channel 7.
AIN1: analog comparator positive input. This pin is directly connected to the positive input of the analog comparator.
XREF: internal voltage reference output. The internal voltage reference 2.56V or 1.1V is output when XREFEN is set and if
either 2.56V or 1.1V is used as reference for ADC conversion. When XREF output is enabled, the pin port pull-up and digital
output driver are turned off.
AREF: external voltage reference input for ADC. The pin port pull-up and digital output driver are disabled when the pin is
used as an external voltage reference input for ADC or as when the pin is only used to connect a bypass capacitor for the
voltage reference of the ADC.
• PCINT6/ADC6/AIN0/SS – Port A, Bit6
PCINT6: pin change interrupt, source 6.
ADC6: analog to digital converter, channel 6.
AIN0: analog comparator negative input. This pin is directly connected to the negative input of the analog comparator.
SS: SPI slave select input. When the SPI is enabled as a slave, this pin is configured as an input regardless of the setting of
DDA6. As a slave, the SPI is activated when this pin is driven low. When the SPI is enabled as a master, the data direction
of this pin is controlled by DDA6. When the pin is forced to be an input, the pull-up can still be controlled by the PORTA6 bit.
• PCINT5/ADC5/T1/USCK/SCL/SCK – Port A, Bit5
PCINT5: pin change interrupt, source 5.
ADC5: analog to digital converter, channel 5.
T1: timer/counter1 clock input.
USCK: three-wire mode USI clock input.
SCL: two-wire mode USI clock input.
SCK: SPI master clock output, slave clock input pin. When the SPI is enabled as a slave, this pin is configured as an input
regardless of the setting of DDA5. When the SPI is enabled as a master, the data direction of this pin is controlled by DDA5.
When the pin is forced to be an input, the pull-up can still be controlled by the PORTA5 bit.
• PCINT4/ADC4/ICP1/DI/SDA/MOSI – Port A, Bit 4
PCINT4: pin change interrupt, source 4.
ADC4: analog to digital converter, channel 4.
ICP1: timer/counter1 input capture trigger. The PA3 pin can act as an input capture pin for timer/counter1.
DI: three-wire mode USI data input. USI three-wire mode does not override normal port functions, so pin must be configure
as an input for DI function.
SDA: two-wire mode serial interface (USI) data input / output.
MOSI: SPI master output / slave input. When the SPI is enabled as a slave, this pin is configured as an input regardless of
the setting of DDA3. When the SPI is enabled as a master, the data direction of this pin is controlled by DDA3. When the pin
is forced by the SPI to be an input, the pull-up can still be controlled by the PORTA3 bit.
• PCINT3/ADC3/ISRC/INT1 – Port A, Bit 3
PCINT3: pin change interrupt, source 3.
ADC3: analog to digital converter, channel 3.
ISCR: current source output pin. While current is sourced by the current source module, the user can use the analog to
digital converter channel 4 (ADC4) to measure the pin voltage.
INT1: external interrupt, source 1. The PA4 pin can serve as an external interrupt source.
74 ATtiny87/ATtiny167 [DATASHEET]
7728H–AVR–03/14