GPIO #2 - this is connected to PB2 on the ATtiny85.This pin is also connected to the onboard LED (like pin 13 on a regular Arduino).

This pin can be used as a PWM output, and is also used for SPI data output.

GPIO #1 - this is connected to PB1 on the ATtiny85.

This pin can be used as a PWM output, and is also used for I2C data, and SPI data input.

GPIO #0 - this is connected to PB0 on the ATtiny85.

The first 3 pins are completely 'free' pins, they are not used by the USB connection so you never have to worry about the USB interface interfering with them when programming

On a 5V Trinket, the GPIO are 5V output level, and can be used with 3V inputs but may damage electronic devices that are 3V input only! On a 3V Trinket, the GPIO are 3.3V output level, and should not be used with 5V inputs. Don't connect a motor or other high-power component directly to the pins! Instead, use a transistor to power the DC motor on/off Next we will cover the 5 GPIO (General Purpose Input Ouput) pins! For reference you may want to also check out the datasheet-reference above for the core ATtiny85 pinĪll the GPIO pins can be used as digital inputs, digital outputs, for LEDs, buttons and switches etc.

Underclock adafruit trinket 5v