this pin is used for USB programming, but it can also be used as a PWM analog output and an analog input known as Analog A2 GPIO #4 - this is connected to PB4 on the Attiny85.This pin has a 1.5K pullup to 3.3V built into the Trinket, for USB comm so it may be difficult to use for analog or digital input. This pin is used for USB programming, but its also an analog input known as Analog A3 GPIO #3 - this is connected to PB3 on the Attiny85.

We didn't want to keep these pins off the board but we strongly recommend not using them unless you're sure you need them since you might have to disconnect any connections to reprogram the Trinket! The best use of these pins is as outputs to things like LEDs. That means that when the Trinket is connected to a computer and in bootloader mode or in the middle of uploading a new program, they are used for sending data to/from the computer! It's possible to share these pins if you are careful. The next 2 pins are also used for USB programming. This pin can be used as an analog input (known as Analog A1), and is also used for I2C clock and SPI clock. 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.

Adafruit trinket 5v 8mhz specs