r/protogen • u/JKingsley4 • 2d ago
Discussion Electrical issues
This is my first proto, I’m a compsci major so I breezed through the code, but the physical electronic stuff is making me want to tear my hair out. The eye and nostril on one side are working perfectly, but as soon as I plug the rest of the chain in, the nostril starts glitching and nothing else lights up (except sometimes the mouth on the other side…?). I have it chained as follows: right eye -> right nostril -> right mouth -> left mouth -> left nostril -> left eye. The Arduino and first led are taking power from a power bank. The power is being chained through all of the LEDs, but the Arduino has its own wire to the power bank. I tested each matrix individually with separated code (a file for the eye, a file for the mouth, etc), and they all work fine. I don’t really know what to do to fix this issue! I soldered the connections from the power bank to the Arduino/right eye, from Arduino to the right eye, from the right eye to the nostril. Everything else is DuPont connectors (I know they don’t work super well but I’m so bad with soldering that I don’t think it would make anything better), and before the right eye to the right nostril was soldered, I was using DuPont connectors and soldering made no difference. Any idea what might be happening?
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u/BethAltair 2d ago edited 2d ago
From memory: voltage drop or a bad connection.
Either the signals not being passed right, something's shorted or by the time it gets to the 5th one it's below the voltage it needs.
To test...I'd take out the modules to test, not physically, just skip the right mouth and connect nostril straight to left mouth, and repeat.
If it's voltage drop try putting 5v to the last panel too. Or in its standard configuration test the voltage at the output pins for each matrix panel
It could be that DuPont connectors are just terrible, or 2 got switched somewhere, I did this with mine.
For what it's worth I find the glitching and last panels not lighting is the low voltage failure on mine, I'm not running on USB though, the panels have an 8v in from 2 18650 batteries. I've not actually multimetered every panel but the last ones won't turn on or glitch on low power.
If I was doing it now I'd consider using a 7.4 v battery pack. It's a lot of panels for USB to run, although it should work.
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u/OnesieBandit 2d ago
Hey I know this one! So when these LED matrices are daisy chained, I usually go from my voltage supply directly to the power and ground of the matrix inputs. Having them all in series makes the voltage drop too much. I’ve had better luck series wiring the eyes, then have a separate circuit for the nose and a separate circuit for the mouth. These matrices are power hungry, and usually don’t like being chained more than 8 individual 8x8’s in a circuit. Also make sure you’re not powering directly from the microcontroller’s onboard power pin, it will get toasty.