How to make a timer with minutes and seconds

Raspberry Pi and Arduino programmable timer

Fosmon [ETL Listed] 2 Pack 24 Hour Digital Timer Outlet, Light Timer with on/off Button, Timer Switch for Lamps, Single Plug In Outlet Timer, Timers for Electrical Outlets Indoor 125V/15A

myTouchSmart Programmable Outdoor Plug-in Digital Timer, 2-Outlets, 26898, 0 Amps

Kitchen Timers for Cooking, Chef Cooking Timer Clock with Loud Alarm,100% Mechanical Desk Timer - No Batteries Required - Magnetic Backing, Exquisite Stainless Steel Body - Countdown Reminder Magnetic

Etekcity Food Kitchen Scale with Bowl, Digital Weight Scale for Food Ounces and Grams, Cooking and Baking, Timer, and Temperature Sensor, 2.06 QT, Stainless Steel

Kitchen Timer (Battery Included), Magnetic Digital Timers Loud Alarm Kitchen Timers for Cooking 2 Pack White, Upgrade Silent Classroom Timer for Kids, Back Stand for Visual Timer