Stopwatch and Lap Timer with Arduino © CC BY-NC-ND

1- Introduction

Stopwatches are very useful in several applications and made by yourself using an Arduino, it is really more interesting!

This project is really simple, easy to be assembled using few components and has an excellent accuracy and responsiveness including the following features:

• The stopwatch shows the time in minutes, seconds and tenth of seconds.
• The lap timer shows the time in seconds and hundreths of seconds.
• Internally the time count is in miliseconds by the clock of microcontroler.

2- Material List:

• Arduino Nano (Uno R3 as optional)
• LED Display with MAX7219 (8 Digits x 7 Segments)
• Tactile Button Switches
• Breadboard
• Jumper Wires

3- Operation

There are 3 tactile button to control the stopwatch:

• Left: Reset the Stopwatch
• Middle: Start/Stop the Stopwatch
• Right: Lap Time

The first 4 digits at left show the stopwatch time and the 4 digits at right are for the lap timer.

Notes:

• Due to the number of digits available in the LED display, the maximum time count is 9 min 59.9 seconds.
• For same reason, the lap timer is limited to 99.99 seconds.
• Beyond these limits, the symbols "----" indicate the overflow of time.