PyCubed keeps blinking green, isn't recognized on computer

[alxklso]

Hello,

I have this PyCubed V5 I'm working with that used to function properly before (could run main.py), and now all of a sudden my computer won't recognize it and the LED just keeps blinking green when I plug it in. I also hear a really faint beeping coming from the micrcontroller when I hold it up to my ear. I did check that my usbc cable works properly. Any thoughts on what could be going wrong?

[maholli]

Hi @alxklso sorry for missing this - I hadn't changed my github email over after graduating 😄

Some questions to help us troubleshoot:

1. Did you build this board or is it one of the heritage ones I built?
2. Is the on-board flash MRAM or NOR? (if it's not MRAM then its NOR).
3. Is the RGB blinking green or is it the CHRG LED?
4. Are you able to access the REPL? If yes, and if it's actually the CHRG LED blinking green (as I suspect it is) read the "The green "CHRG" LED blinks when I plug my board into my computer" section of the PyCubed Troubleshooting Page
5. Are you able to reach the bootloader? See step 4 of the Updating PyCubed page

[polygnomial]

Hi @Alpacentauri1 — double checking, did you use the UF2 from here: https://circuitpython.org/board/pycubed_mram_v05/?

The firmware on the PyCubed GitHub firmware repository is not meant for MRAM

[Alpacentauri1]

Hi. @polygnomial - Yes, I used the UF2 from there: https://circuitpython.org/board/pycubed_mram_v05/. The newsest version was downloaded and used. But it is still PYCUBEDBOOT, not CircuitPy or PYCUBE after the file was done transferring even though I got the board reboot again but it was not mounted as CIRCUITPY or PYCUBED.

[maholli]

Loading the bootloader over SWD was successful, so all good there. What you describe (adding the UF2 file but still ending back up in PYCUBEDBOOT) means there is something wrong with either (A) the firmware build configuration for your particular MCU/MRAM combo or (B) possibly something electrically wrong with the MRAM.

@Alpacentauri1 just to double-check since I can't quite tell from the pic - what's the full part number for your ATSAMD51 installed on the board? Nevermind. I can make the part number out. All good there.

IMPORTANT: from your pic I can see that both the RF LDO and its alternate are populated. This should never be the case (see the BOM or note in the schematic). I don't believe it is causing your firmware issue, but you should still remove the one I've circled in red (leave the neighboring resistors and capacitors).

[polygnomial]

Electrical issues

• Do you have any blank PCBs? If you do, I'd try probing the QSPI to make sure the MRAM is actually connected to the SAMD51. Edit: these should be from the same run of PCBs. It's also possible this specific board has issues—do you have other assembled boards? Do they behave the same?

Firmware issues:

• Try using one of these older firmware binaries: firmware.zip. I don't have a V5 PyCubed on me right now, but I've used these binaries in the past on J19/MRAM boards.

[Alpacentauri1]

Dear @maholli , @polygnomial . Yes I did it succesfully. The problem was the version of CircuitPy. As you described, I selected one of firmaware version 8s such as https://adafruit-circuit-python.s3.amazonaws.com/index.html?prefix=bin/pycubed_mram_v05/en_US/. then I got success. But any version 9s was not good for J19/MRAM board. I dot not know why this problem happened.
I hope this episode can be an improvement for upgrading PYCUBED. Many thanks for your interests and advices on these tasks.
By the way, @polygnomial, I can send you a J19/MRAM board. I have several available boards.

[polygnomial]

Are there any features you need on CircuitPython 9? If not, I would suggest using version 8.

The autogenerated CircuitPython binaries are built with files that are stored on the Adafruit CircuitPython repository—they change the format every so often so it's possible that is where the issue lies. It's also possible that there is a deeper issue here in CircuitPython—the PyCubed boards are the only CircuitPython boards that use MRAM, and the new versions of CircuitPython are most likely not tested on all boards before release.