10/18/2023 Map Stopped Working?
Visit this post for the fix
Trying to setup my first map and running into some issues when I attempt to power the Pi Zero 2 with a 5v/10a/50w PSU.
When I power the Pi via micro usb, the LEDs behave as expected with no issues. As soon as I abandon the micro usb power and provide power via GPIO 2 (or 4 or both), the LEDs start to act crazy which has me thinking it's more than likely a grounding issue. Checkout the attached picture for the basic breadboard testing setup (the green/yellow wires running from off screen are the - and + from the PSU respectively):
Not pictured are the other 4 (5 in total for testing) WS2812b neopixel LEDs that are wired up. There really doesn't seem to be a rhyme or reason as to what LEDs come on when I turn the map on, turn on the test script, or manually go through and turn on specific LEDs through the airport config section.
Any thoughts/suggestions would be greatly appreciated!
Hi,
Looking at the picture you posted (thank you for that) it looks like the level shifting chip is miswired. It seems the signal from the RPi and the wire going to the Din to the LED's are in the wrong pins of the chip. So take a close look there and let me know. Here's a picture of how it should be wired. - Mark
Hi Mark-
Thanks for the quick reply! I should have provided a bit of additional context as it pertains to the level shifting chip....
I had a difficult time initially making the Din wiring work using 1A and 1Y, so I switched over to using the 2A and 2Y (pins 5 and 6 from the picture below) as I read that it was a second channel to step up voltage. As far as the additional ground on pin 4, I don't recall where I saw a diagram that included it - but after adding it, things worked as expected with Din on 2A/2Y (perhaps a faulty level shifting chip? A replacement is on the way from Amazon currently). I added the diagram for the 74LVC245 in case anyone searches for this in the future 🙂
I just tried to change the wiring as per your picture and now no LEDs will turn on:
Quick correction, the level shifter that I have in the picture is the 74AHCT125N
Ok, I'm not familiar with that chip (N) and its behavior. So I have to wonder if that's the issue. There is information out there using a Diode instead in case you wanted to try that. You can look here; https://www.iflymn.com/2020/02/livesectional/ for info on the Diode.
Also, some people have said that it works with the 5v to the LED's instead of 3.3v, but I've not tried that. Might be worth trying for diagnostic purposes. - Mark
I just tried bypassing the level shifter and the string of 5 LEDs works just fine/as expected while also powering the Pi with the 5v connected to pin 2. Seems like something funky with that level shifter for sure. I bought the one that was linked from the build guides under the Start Here section of this site...maybe they changed what was being sold? I'm not finding the "non N" version of that level shifter. Curious to see if the replacement one from Amazon arriving tomorrow will work any better....
I'll update as I learn more.
Good diagnosis on your part. I'll bet the new chip will work just fine. - Mark
As a quick update - the new level shifter definitely solved the problem (I ordered a few more to have in stock, haha). Not sure what happened with the original one, but all works as expected now!
Great news. It just shows you can never be sure. I always order at least 2 of everything for this reason. 🙂
Mark
