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Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
@user58511
I'm a purely software guy, I fart around w/hardware but this is the most complex thing I've ever done
I have built a pico controlled power strip - I opened up a USB wall-wart and stuck it in the powerstrip and ran 5v up to the Pico - then I ran 3v back down to the power strip to toggle the relays (using a shift register chip.) The intermediate box uses an old 5v LCD I had from my Arduino days. The relays are powered via 5v and triggered w/3v. The final box is just a connector for switches. I figured out how to stack diodes so that I can handle 7 switches from 4 wires.
problem #1 -- we call this thing the ouija-switch because turning other lights and/or tv's on/off in the room can make this thing turn outlets on/off, it's particularly bizzare to me because the LCD readout says that the relay has toggled. And of course it's getting driven by the Pico, so how can EMI (which it has to be) get up through the Pico out into the 3v world and make the software think I hit a switch?
answer #1 -- a guy at work with an EE background says that I'm getting power fluctuations causing harmonics which are screwing up the works, and that they can run rampant all over the place. He gave me 5-6 solutions using terms I had no idea (shunts, capacitors, inductors, etc.) until the 7th -- power the Pico from a battery, if all your problems go away then you can think about cleaning the power to the Pico. (and have I read notes from people on other projects involving relays say things like: use a decoupling capacitor and liberally sprinkle capacitors around your circuit. Liberally Sprinkle ?? I have no idea what-all he was talking about)
The Big Question -- if I throw a 9v battery into the middle box and connect that to the Pico then I will have 9v & 3v sharing the same ground, I used to have the 5v and 3v sharing the same ground. Is it alright to share the ground between 9v & 3v? Was the shared ground between 5v and 3v the source of my problems anyway? What should I do? I would rather not add a battery but rather fix whatever the original problem is that is causing the ouija-switch behaviors.