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HARDWARE/WRITING ISSUES WITH GEMMA M0
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HARDWARE/WRITING ISSUES WITH GEMMA M0

by steamtruck on Tue Mar 09, 2021 5:01 pm

Greetings, we are using the GEMMA M0 with about 500 students, and my staff is reporting the following issues. We would greatly appreciate solutions we could provide to help the students troubleshoot these issues. We have multiple students experiencing all of these issues. They are all on Chromebooks.

1. When we are wiring up the hardware and putting the code on there some of the students are getting bright pink lights. We are aware that the bright pink lights are some type of hardware issue but we don't know how to fix it.
2. Students are putting code on the led and only one pixel is lighting up although their code has 120 pixels in it.
3. Students are plugging into the usb port and the gemma driver doesn't show up. We have tried resetting the board, unplugging it and cutting it off. Still isn't working. They are plugging everything in correctly.
4. Students are having trouble resetting the board. Sometimes it is taking up to 10 mins to get it to change from circuitpy to Gemmaboot. Online the only resolve we found was to keep pushing the button until it responds. This is too time consuming and isn't a guarantee.

Many thanks!

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by adafruit_support_carter on Tue Mar 09, 2021 5:53 pm

Hi. I think we need a bit more info. See below.

1. What is getting wired to what? Can provide more information on the hardware (other than the Gemma M0) being used.
2. Can you link or post the actual code being used? Also, what is the LED hardware being used?
3. By driver, do you mean drive? Like seeing GEMMABOOT or CIRCUITPY?
4. Wow. So this can happen by just double pressing the reset button and waiting? It can take 10 mins for GEMMABOOT to appear?

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by steamtruck on Tue Mar 09, 2021 7:17 pm

Hi Carter, thanks for your reply. My responses below.

1. The students are wiring programmable LED strips to their GEMMA M0. The connection wires on the LEDs have been pre-stripped for them, and they are attaching to the GEMMA M0 mechanically via the bolt kits.
2. The code we used as a baseline is here: https://learn.adafruit.com/neopixel-spa ... h-makecode
The LED hardware is here: https://www.superlightingled.com/ws2812 ... p-167.html
3. yes, they mean drive. They connect the GEMMA via usb and see nothing (GEMMABOOT or CIRCUITPY) appear as an external drive.
4. I will triple confirm how rapid the double click on the reset button needs to be to distinguish between single and double click, as I learned when I tested the lesson plan. But yes, this is what my staff is reporting.

Would appreciate any feedback you can provide. Thanks so much!!

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by adafruit_support_carter on Tue Mar 09, 2021 7:52 pm

Thanks for the additional information. It helps understand the setup better.

For 1 and 2 - Can you "share" one of your example MakeCode projects and then paste the publish link here.

For 3 - Since you are using MakeCode, you'll only see the GEMMABOOT folder. Is this "no drive showing" happening to all the boards? Or just some?

For 4 - Here also - this is happening with all the boards?

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by steamtruck on Tue Mar 09, 2021 8:35 pm

Waiting for confirmation from staff on the actual code they are developing w/students.

For 3 & 4, they tell me it's happening for 5-10 students per class (4 classes/day)

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by Shalice on Wed Mar 10, 2021 12:47 pm

The code the students are using is:

On Start Loop (code is within)

Set Strip to WS2812 stip on D0 with 120 pixels
Set Strip all pixels red
Set strip brighteness to 255

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by adafruit_support_carter on Wed Mar 10, 2021 1:45 pm

For the 3/4 issue - when this happens again, try and set aside that particular GEMMA *and* USB cable being used. And then we can try some additional steps with that hardware.

Does a teacher, or someone else, have access to a PC (something other than a chromebook) for help in troubleshooting the LED issue?

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by Shalice on Wed Mar 10, 2021 2:42 pm

All of our teachers and students are working virtually from their own homes. Students received materials packets with everything in them. So Im not sure about being able to set outside the gemma and usb. Each student only has 1. The lesson plan was built around all of students being on chrome books, and our staff is trouble shooting from chrome books.

We just had a teacher try to test issues 3/4 on a pc and the driver isn't showing up on her chromebook but shows up on her pc. Again all of students are working on chrome books tho.

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by adafruit_support_carter on Wed Mar 10, 2021 2:53 pm

We just had a teacher try to test issues 3/4 on a pc and the driver isn't showing up on her chromebook but shows up on her pc.

Can this teacher continue to troubleshoot? The idea would be to try and figure out how to get their chromebook to work, and maybe that would be the solution for the other students.

Has anyone been able to get the LED strips to work? As a way to verify the hardware combo, since there can be some variability amongst these addressable LED strips.

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by Shalice on Wed Mar 10, 2021 3:02 pm

yes the teacher is trying to troubleshoot. Many of students and all of teachers have been able to get their led strips to light up.

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by adafruit_support_carter on Wed Mar 10, 2021 3:08 pm

OK, so the hardware combo notionally works. Do you think you are able to adequately verify the students wiring connections? Also, power could be an issue. But you could deal with that by setting the pixel count lower. You don't have to drive *all* the pixels on the strip.

Let me ask others here about the chromebook issue.

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by kevinjwalters on Thu Mar 11, 2021 10:00 am

For the RGB LED strip are there 120 plugged into the Gemma M0? How are these powered? It's common to use a 60mA estimate for maximum power use per LED, 120*0.060 = 7.2 amps which is a lot of current and way beyond the typical 500mA that comes out of the 5V power line on a desktop/laptop computer's USB port. If the RGB LEDs are powered from USB then lighting up all 120 red elements is going to try and use about 2 amps and the power supply could be current limiting with adverse consequences.

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by steamtruck on Thu Mar 11, 2021 11:48 am

The strip is powered by a 3xAAA battery pack. In our tests on multiple LED strips from different manufacturers, we were able to light the entire strand without issue.

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by kevinjwalters on Thu Mar 11, 2021 2:01 pm

I just tried this on a Gemma M0 using https://makecode.com/_PaAe1WLTLRsV and it works for me with an unbranded 12 element WS2812 strip. I'm using the USB power available from the Gemma as Vout which means I only need a single ground wire. These are red underneath, I had to put a sticky note on them as they are too bright for camera otherwise.

gemma-m0-makecode-neopixels-twelve-red-1.JPG
Gemma M0 running Maker MakeCode to set 12 WS2812 RGB LEDs to red
gemma-m0-makecode-neopixels-twelve-red-1.JPG (235.73 KiB) Viewed 3144 times


An example picture of your wiring/setup might be useful.

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Re: HARDWARE/WRITING ISSUES WITH GEMMA M0

by adafruit_support_carter on Thu Mar 11, 2021 6:23 pm

Agree that 3xAAA battery is generally not enough for 120 NeoPixels. But power requirements is a whole discussion, good info here:
https://learn.adafruit.com/adafruit-neo ... -neopixels

2. Students are putting code on the led and only one pixel is lighting up although their code has 120 pixels in it.

Is it always only one pixel?

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Please be positive and constructive with your questions and comments.