Handheld Vibrating Timer Prototype using Trinket

There are times while exercising when it would be useful to have a simple one-button hand-held 30-second timer that vibrates. At least that's what my wife tells me. This seemed like a good excuse to play with Adafruit's mini microcontroller called "Trinket". These are an $8 tiny board built around the Atmel ATtiny85.

The idea of the device is simple. You press the button, and it vibrates quickly to notify you that it is armed. Then after 30 seconds it vibrates again to say the time is up. I might modify it later so that two quick pushes sets a 60 second timer, but I'm starting simple.