M4 Causing first Neopixel to get stuck on red Moderators: adafruit_support_bill, adafruit

[brinc0]

Hello,

I'm following the Rezz Goggles guide (https://learn.adafruit.com/rezz-inspire ... s/overview) and whenever I power on my Itsy Bitsy using the code provided, the first Neopixel in the triple ring is stuck on red. The rest of the pixels behave normally.

I've tried using a different pin (the guide says to use #5). I've also changed the code to only illuminate the first pixel with (0, 0, 0) values and the pixel still shows bright red.

I've verified the issue persists when testing with the other of the two triple-rings I have and have also tested using an Arduino Mega 2560. When using the Arduino, both Neopixel rings behave normally. So that leaves one last component (I think), the Itsy Bitsy. I'm not sure what else to test on the board itself so I'm just looking for any ideas on how to resolve the maxed out red value or verification that the board may be faulty.

I'm using a USB cable connected to my PC to power the board and Neopixel ring if that's relevant.

Thank you

[daddintech]

While not the exact same issue, I ran into a problem with my ItsyBitsy M4 Express tonight in which the first led of an 8-count Neopixel strip stuck on green. My board was powered through a USB connection as well. As soon as my first switch was made, the first led would light solid green at 100% while the remaining led’s operated as they should. A board reset would not turn the led off. I would have to eject the board and the cycle would start again. I tried multiple different pins for the data signal as well and the Neopixel strip was powered from the USB pin. I then swapped the Neopixel strip over to a Trinket M0 and it worked just fine. I had to complete my project with two Trinket M0’s because I could not figure out how to get the M4 to work correctly with the led strip.

Edited to Add: The boot loader is up to date and I was using the newest libraries.

[brinc0]

I also just finished updating my bootloader and installing the latest Circuitpython libraries. Still have the same issue. I ordered another M4 so I hope that one works as it should once it arrives. If it doesn't, I may have to explore the solution you mentioned of using a pair of Trinkets.

[daddintech]

I hope the replacement board works out for you! I have seen other similar posts online regarding a stuck pixel with different boards and most of the responses have been that it is either a bad board or bad neopixel. I have seen a few people comment on the possibility of the problem being a bad data signal or even a bad solder joint. I have also seen numerous posts regarding placing a resistor in the data signal wiring. Now, I did not try including a resistor. I do know my issue wasn't a bad solder joint though because I reworked all of my solder connections and the problem remained with my M4. While I don't know this for sure, I found a printed "4520" on the back of the PCB which I am assuming is a date code indicating the 45th week of 2020. Out of curiosity, do you have a four digit number silkscreened on the back of your PCB near the USB connector? If so, what is that number? It may not mean anything, but I was wondering if it could be a batch issue. Probably not, but just a thought. I am new enough to this aspect of the maker world that I do not know how to track down the precise cause of this issue with the M4.

The project I was working on was a footpedal switch for PTT functionality in PC FPS games. I also wanted a set of neopixels to illuminate under the lip of my desk above my keyboard drawer. Unfortunately, a single Trinket M0 Express did not have enough memory to import all of the libraries I was needing to use to achieve this functionality. I could get the footpedal switch to work or the neopixels independently, but not together. So, I used one Trinket for the foodpedal switch which sent a signal to a second Trinket that powers/controls the 8 count Neopixel strip. It all works great at this point, but I still would like to figure out why I couldn't get the Neopixels to fully work with the M4.

Again, I hope it all works out for you with the replacement and that is the solution to our problem. If not, I will keep digging, trying to figure this out.

[brinc0]

Ok -- I found a solution to my issue. TL;DR is the version of CircuitPython I was running was causing the first Neopixel to stay illuminated Red. When I got my Itsy Bitsy, I upgraded the CircuitPython version to the latest version, because why wouldn't I? At the time of writing this, that version is 7.x. However, the version of CP in the guide is 5.x. I haven't dug into the changelogs in Github yet to figure out why or how this seemingly "breaking" change was added. Once I downgraded to version 5.x, the code worked immediately and my issue was resolved.

The guide said nothing about version 5.x being a requirement and a friend of mine is running version 7.x on another set of Neopixels and they don't have my issue at all. So I'm not sure if it's a combination of the triple-ring with the latest version or what.

Of course, I discovered this after I purchased another board. Oh well, at least I have a board for another project.

[daddintech]

Thanks for the update! I will try downgrading to an older version on my board to see if that helps. Right now, the Itsy Bitsy M4 that I have is being used as an input device to set hotkeys with a keypress utilizing the F13-F24 function keys.