Conveniently check your heart rate when you've finished a set, then start the countdown timer for your rest period. The timer is adjustable in 30 second increments and vibrates when your time is up.
Larger text so you don't have to squint and modified vibration pattern so you can't miss it. I'm intending this to be the final version, so if you want some modifications send me a message and I might be able to accommodate a custom build for you.