Datasheet

GPIO #1 - this is connected to PB1 on the ATtiny85. This pin can be used as a PWM output,

and is also used for SPI data output. This pin is also connected to the onboard LED (like pin

13 on a regular Arduino).

GPIO #2 - this is connected to PB2 on the ATtiny85. This pin can be used as an analog input

(known as Analog A1), and is also used for I2C clock and SPI clock.

The next 2 pins are also used for USB programming. 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 best use of these pins is as outputs to things like LEDs , or inputs to things like buttons and

just make sure not to press the buttons while connected to USB. 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!

GPIO #3 - this is connected to PB3 on the Attiny85. This pin is used for USB programming,

but its also an analog input known as Analog A3

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.

GPIO #4 - this is connected to PB4 on the Attiny85. 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

Reset and Regulator Output

The final two pins are at the bottom of the board.

First is the Rst reset pin. This is connected directly to the ATtiny85's reset pin and also the reset

button which is right next to it. The reset pin is used to enter the bootloader and to reset the board

in case you want to restart it. It's also possible to use this pin to re-program in the bootloader or

completely remove the bootloader if you have an AVR programmer such as an AVR Dragon, MKii or

USBtinyISP. If you want to re-program the board when its in an enclosure or box or otherwise hard

to reach, wire a simple button from the RST pin to ground and press it to enter the bootloader for 10

seconds. The #1 LED will pulse to let you know. The reset button cannot be used as a GPIO, but we

think its a lot more useful as a proper reset button!

Lastly we have the regulator output pin. There is an onboard mini power regulator that will take up

to 16V DC from the BAT+ or USB connection and regulate it down to a steady 3.3V or 5.0V DC so

Note the numbering of analog pins: Pin 2 is Analog 1, Pin 3 is Analog 3, Pin 4 is Analog 2. For

the Uno, the terms A1, A2, and A3 are mapped for you. For ATtiny85's, they are not. So for

the pinMode calls, use the Pin number (stenciled on Trinket), for analogRead, use the analog

number.

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Industries

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