Airsoft Rounds Counter

Browsing around on AVRfreaks' forum I stumbled upon this thread about an Airsoft Round Counter to display the number of remaining rounds when playing airsoft. This is obviously a cool idea and the thread inspired me to want to make one myself.

In the thread people discussed using everything from a simple switch attached to the trigger over photo interrupters and photo reflectors to accelerometers for detecting when a shot is fired. There is also a link to this page on the Design Decisions Wiki where a group of people have designed an "Airsoft Electronic Ammunition Counter" with detailed design considerations and requirement analysis and timing calculations. Excellent work and a great source of inspiration for this project.

My initial considerations for this project:

  1. Enclosure. Everything should be mounted to an airsoft gun and it shouldn't be the size of a shoe box!
  2. Component count. This ties in with number 1 above: if this is to be small enough to be portable I have to keep the component count down so the final PCB is of a manageable size. (Yeah yeah, "use SMD". Right, I'll do that in phase 2.)
  3. Ease of use. This will be used in skirmishes so it should be real easy to use. No re-flashing of the processor to change settings, easy to attach to a weapon and so on.

So far I have settled on the following basic components:

  1. ATTiny 2313-20PU. I could probably get by with a smaller ATTiny but since I already had a couple of these lying around I went with those...
  2. Four-digit 7 segment display
  3. Maxim 7219 CNG display driver.
  4. Wide-gap photo interrupter

Off to EAGLE for some schematic drawing and thence to the breadboard for figuring out how photo interrupters actually work...

Leave a Reply