Troubleshooting Only First Light on Neopixel Works

[lmur...@vt.edu]

Hi All!

We're in the process of building some new FED3 units, and are running into an issue that we don't know how to solve. After we've gotten the entire unit together, we've found that sometimes only the first light of the Neopixel strip works. Does anyone know whether this is the result of a soldering issue on the Neopixel itself or somewhere else on the PCB? 

[Lex]

Hello!  Cool you're building them from scratch! What you describe is almost certainly a soldering issue with the LEDs.  All of the LEDs are controlled by a single digital data line so if you're getting one of them to light up it means that data is working, but LEDs 2, 3, etc are not seeing the data.  These LEDs are challenging to solder, if you can share photos I can perhaps give you more tips, but I would focus on LED #2 first, and just try to make sure all four solder points are good.  If this fixes it then move to #3, etc.

On Fri, Apr 15, 2022 at 7:40 AM lmur...@vt.edu <lmur...@vt.edu> wrote:

Hi All!

We're in the process of building some new FED3 units, and are running into an issue that we don't know how to solve. After we've gotten the entire unit together, we've found that sometimes only the first light of the Neopixel strip works. Does anyone know whether this is the result of a soldering issue on the Neopixel itself or somewhere else on the PCB? 

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[lmur...@vt.edu]

Sorry, re-posting because somehow my comment posted using a burner e-mail account rather than through my preferred (and original poster) account.

Oh, we're not building the neopixel board from scratch, we're using the pre-made strip of 8 that's suggested. We've tried checking the soldering, and they seem okay. We use the liquid solder rather than traditional soldering, as we found that the best way to ensure that the IR photobeams reach far enough out to the pellet well is to make sure the light is as flush as possible with the PCB itself. 

Is there some code we could create that we could use to test the lights before we've built the entire unit? Something that we could load to a feather m0 and test when just the arduino and lights are soldered on?

[Lex Kravitz]

Cool that works, I always found that part to be the most difficult to attach. We found that solder paste and a heat gun was the best approach, as described in step 5 of the instructions.

To test if you have it working you just need the Neopixel strip and the Adalogger headers on the PCB.  You can then plug in an Adalogger and flash the attached code (it's a very slightly modified version of the Adafruit "simple" example code for Neopixels).  You should see them light up one by one as below.  If you see them all light up during this step you're good to go!

One final idea - are you using the RGBW strips from Adafruit?  They make several similar versions of this part and if you purchased the RGB ones (without the white LED) you'd get strange behavior from them.  You can still use those in FED3 BTW but you would have to modify one setting in the code to specify that you're using a different Neopixel strip.  Anyway thought I'd check on this!

[lmur...@vt.edu]

Based on pictures and a part number located on the back (E466616) it appears to be the RGBW. Thanks for the code! We can dedicate an extra feather board so that we can just test them as we make them, rather than find out after everything is finished that the LED doesn't work.