So who knows stuff about the #commodore64 light pen?
Was there an amplification circuit for the light sensor input?
It clearly is responding when I point it up at my task light, but it's barely 30mV. Just no idea if that's what I should be seeing. Also no idea why the 'floor' goes negative...
One button is 5V high and properly drops to 0 when pressed as expected. the other button doesn't seem to work, but the CGA only supported one button anyway.
@gloriouscow Oh wow, you just brought back a memory. I built a light pen for the c64 when I was a kid from a book, it was one of my first electronics projects. It was little more than a photo transistor and a joystick connector. Not sure what the official one is like.. mine keyed off of the refresh rate of the CRT.
Going to see if I can find that book. It was green, with a ring binder
@gloriouscow This _might_ be a scan from it. It had to have been pretty simple like this.
gloriouscow
cmars 🅅