Digital 9 - this pin can also be used as a PWM output pin using analogWrite() It's also good for driving servos because its a high-speed PWM output.

Digital 8 - Nothing particularly special about this GPIO pin.Digital 6 - this pin can also be used as a PWM output pin using analogWrite().Digital 5 - this pin can also be used as a PWM output pin using analogWrite().Digital 4 - Nothing particularly special about this GPIO pin.Digital 3 - this pin can also be used as a PWM output pin using analogWrite().TX - also known as Digital #1, this is the hardware serial output pin.RX - also known as Digital #0, this is the hardware serial input pin.You can find more info for Trinket pinout in official Adafruit site here. Mounting holes, you can easily attach it to breadboard or plug it in your own circuit board!.

Works with 99% of existing Arduino sketches (anything that doesn't use more than 28K, and doesn't require pins #2 and #7).Reset button for entering the bootloader or restarting the program.On-board green power LED and red LED at pin #13.

Power with either USB or external output (such as a battery) - it'll automatically switch over.

Up to 16V input, reverse-polarity protection, thermal and current-limit protection.

On-board 5.0V power regulator with 150mA output capability and ultra-low dropout.

Micro-USB jack for power and code uploading.

Adafruit trinket 5v keyboard