I've been working on the exact same thing, ammo counter/chrono/voltmeter all in one, (https://github.com/etnom/ming-batt) and even in that same optic, haha. I just haven't found the time to work on the hardware. Mine includes a wireless barrel attachment and optic, but this is amazing!
It must've been a pain writing all the display functions and initialization, I use two libraries for a similar display, in case it may come in handy:
- https://github.com/a...afruit_SSD1306:OLED driver library
- https://github.com/a...it-GFX-Library:Graphics library
Nice! I am jealous of how well organized your code is (my 'training' if you call it that, is very informal... a googled expansion from one semester of C in college LOL). The optic setup is almost ideal isn't it? I found it after researching several 'Arduino chrono' projects. I honestly got a bit worried when it started to get a weak signal at >1.25" separation, but it's just a nerf gun. So upping forward current to near max continuous rating was an easy decision, LOL. Screw playing with discretes, analog amps, ...bah! Optek stuff rocks!
I'm curious to see how you went about the wireless part. I've got an assortment of spare 'robotic' radios I could play with (433,2.4,SPI,UART,ESP82xx, etc)... I thought it would be cool to develop a system that has various attachments (barrel sensors, red dot screens, etc) and guns (firing mechanisms, motors, etc) essentially 'talking to each other'. Unfortunately that would take more time that I alone have to put in to this stuff. Although if someone is already started, I don't mind donating some lines of code. This idea could be developed to include GPS, inter-troop data sharing... a modern comprehensive networked battle system for nerfers LOL! How cool would that be, to glance down at your phone and see your friendly positions, last known enemy positions, friendly ammo counts, etc? That would be a real advantage IMHO... and I bet there are nerfer clans who would demand to have it if it was available.
OTOH, a simple 'look ma no wires' application could be fun... for example a pair of 328's linked via NRF radios (or whatevers ya' got on hand), one reading the sensor and processing data, the other displaying data on a screen (and possibly responding to muzzle data for physical 'on gun' functions... ex. killing flywheels when the clip is empty). Nobody likes wires, and this idea could remain modular (just keep the gun specific code on the gun uC, and leave the muzzle code generic so it works with many gun/sight setups). My guess is something like that would be enough to meet all needs of the average nerfer.
So many ideas, so little time. I think my next step on this project will be to play with controlling my son's stryfe motors using AnalogWrite(). That's a more reasonable goal to reach in a couple free weekend hours (whenever that comes next).