I have the first prototype of the Airsoft Rounds Counter up and running on a breadboard.
Here is the schematic. A couple of notes:
- A 10 µF capacitor or so near the power supply certainly wouldn't hurt. Neither would a diode on the input side of the 7805.
- The "program and reset" switch doesn't do anything with the current code and can be omitted for this version.
- On the breadboard I also have a tact switch from the ATTiny's RESET pin to ground so I can reset the counter.
- I'm using a 9V battery for power.