• LoopA

  • No midi after firmware upload

Hello!

I’ve reached the part where I flash the MCU, however I had IC1B put on backwards and toasted it. I installed a new one (right way this time) and flashed the hex file to the MCU again. When I start MIOS and select the Midi In/Out ports it shows MIOS32 only.
Is the MCU flashed properly or did I do more harm than good?

    I would hope that the damage would be limited to that chip, but maybe something else has gone wrong. Top candidates are:

    1. MIOS Studio wasn’t restarted. Re-enumeration of USB ports is required after resetting the Core.
    2. SEQ USB/OTG switch is in the OTG position and tries to connect as a host (should be slave -> “USB”). Or Waveshare OTG jumpers are still in.
    3. MacOS drivers need resetting:
      Start the Audio-MIDI-Setup of MacOS (e.g. search for “audio-midi” with Spotlight)
      Disconnect the core module from USB
      Delete the interface in the Audio-MIDI-Setup
      Connect the core module to USB again
    4. Waveshare settings are wrong:
      Boot Config: Flash
      Power: 5V In
    5. Boot0 resistors (R101/R102) are not installed.
    6. Cabling issue.
    7. Insufficient or noisy USB power.

      Are you still able to communicate over USB? If so, it might be worth trying to reflash the SEQ app again.

        I’ve tried the aforementioned things and I only get a flashing power light, nothing else. Jumper J15_S is set to 3v3 as well.
        Could The MCU be toast?

          Flashing power LED might mean that the MCU is stuck in the bootloader. You could try to reflash the bootloader here:
          http://ucapps.de/mios32/mios32_bootloader_v1_018.zip
          Make sure that you use the F4 variant.
          If that doesn’t work, then something else could be amiss. The options then are to try to use an ST-LINK/JTAG programmer as an alternative to USB, or maybe the MCU has gone indeed.

          @diyguy if your core responds to commands in MIOS studio, it might not be toast - if you’re building a LoopA, check that you’ve installed R101/R102 - if not, the core may be stuck in bootloader mode, as Andy said.

          If these are installed, as Andy also suggested, i’d recommend to get an original ST-LINK V2 and reflash directly via JTAG - you could follow this nice tutorial by @Phatline :

          Best regards,
          Peter

            So I see where I went wrong: I was following the video build guide and noticed that R102 was not installed; I should have checked the BOM (which you clearly mentioned in the same video Peter 😅)
            I’ll get that onto the board and get back to you here.

              That will probably do it (I amended my list with Peter’s suggestion of R101/R102)! The missing resistors mean the boot state is undefined, so it can default to “Boot Hold” where loading of the program is halted and it hangs in the bootloader. This is done if the firmware is somehow corrupted and you want to try again.

              Here’s hoping that adding the resistors will solve your issue!

              Best,
              Andy

                I installed R102, flashed the bootloader and firmware, refreshed the Mac Audio/Midi, plugged in the LoopA and it’s working!
                Can’t thank you enough for your quick responses and help with this.

                Lesson learned: CHECK THE BOM!

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