Sparkfun Pro Micro Homemade Issue

We have better things to do than ridicule people’s wiring.
Mocking others for their lack of a specific ability is the pursuit of those with smaller minds. :P

I’m not exactly a hardware expert but two things being ‘fully on’ seems a bit too coincidental to be unconnected.
From a software perspective it sounds like both devices are being sent an all-high/all bits on signal (as @tuxinator2009 suggested), but I don’t know enough about hardware to suggest what might cause that.

I think @Mr.Blinky’s suggestion of probing some things with a multimeter might be a step in the right direction.

I ran some tests since I have the same display and pro-micro and have ruled out the possibility of selecting the wrong board type. Testing each type in Mr.Blinky’s package just resulted in shifting of the screen but not an all white display. So it’s definitely something with the wiring, though all the wires look like they’re going to the right pins and there doesn’t seem to be any solder bridges (however, sometimes I’ve found everything looks fine until you look at it under a loupe scope only to find a tiny little strand of solder bridging a connection).

If you don’t have a loupe scope I recommend this one on Amazon, it’s cheap and works great for this type of work.

Otherwise the only other test is to use a multimeter and do a resistance test to see if any wires are showing a connection where there shouldn’t be (ie. connect probe to 2 different pins and see if there’s a connection between the two).

You should see my first attempt at soldering wires and chips to a protoboard. Only ordered 22 gauge solid core wire for breadboarding and it didn’t want to co-operate. Ended up burning out not one but two 4-digit 7-segment displays during probing testing the leds on the display because I accidentally bypassed the in-series resistors and sent straight 5v through them. I still have the mess on my shelf as a memento to my introduction to small-scale electronics.

I did some multimeter testing and did not find any pin bridges. However, there is definitely a deeper fundamental issue somewhere because on a hunch I disconnected VCC from the display and it stayed fully lit. Unless I am misunderstanding what VCC is for! I then disconnected all display pins to see if at least the sound would work absent the display but no luck there. When I get a chance I’m going to remove the micro from the pcb and try to “start over” with no connections.

I would like to extend a HUGE THANKS to everyone here for engaging with me! Very fun so far despite my failures :slight_smile:

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When you disconnect Vcc the display gets powered by any of the signals that are at high level through the built in protection diodes on those pins. This is normal behaviour (but bad practice)


Ah okay, thank you for the knowledge.

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