Bricked MCU Core?

dcbf84ceef5b5704

Hi All,
Ive been slowly working on an Seq v4+ for the last few weeks, following along hawkeye’s videos and it been going well so far. All the testing along the way has worked ( after a little reflowing here and there on the UI boards).

Today i have been assembling the case. At the stage where it is time to upload the firmware, i am getting no midi ports found in mios studio. I figure no problem, I’ve probably pulled an IDC cable loose along way. Backtrack disassbling and try again without the UI boards in the case and double checking to push in all idc cables. Now I see midi ports again.

For sone reason i thought “lets try installing the seq v4+ firmware now and then build up the case again testing along the way”.

So i follow those instructions, putting the RH harware config in the root (using MIOS studio) and upload the firmware. Upload says successful but nothing happening on the displays. Tried a power cycle, still nothing. Midi ports not showing up. Now i’ve strippped it back to just the Core MCU / PCB and USB PCB , and Res-SD PCB, but still whem connecting the USB to my laptop no midi ports showing up.

The green LED by the SD card lights up and the red power LED on the waveshare.

Im sort of at a loss what to do now- any suggestions?

Feeling somewhat disheartened- I thought I was about to ve finished, but now nothing is working!

17703227d9536da1

Bad cables are often the issue but they won’t affect what ports you see in MIOS Studio. Generally you shouldn’t upload a firmware file unless you can contact the core with success.
Things to check:
Do you have Core resistors R101 and R102 installed? The jumper on the other side of these can be used to hold at the bootloader, which normally allows you to reload firmware.
Have you got the USB OTG switch set to “USB”?
Are the jumpers on the waveshare set to Boot Config: Flash and Power: 5V In?
Have you tried to reset your MacOS MIDI ports (if using a Mac)?
Is your USB power supply powerful enough?

dcbf84ceef5b5704

Thanks for the reply!

Up until then I’ve been able to connect with the core without issue- installing midibox ng and related testing all went fine.

All resistors in place and switches/jumper set right.

The jumper you mentioned that halts at the bootloader- this was successful! The mios bootloader showed up in my USB devices, and USB midi ports appeared- thank you!

I’ve flashed the seq v4+ hex file now. Im not sure but I have a suspicion i choose STM32 instead of STM32F4 last time. Perhaps thats where I went awry.

And now the next issues presents itself. Based on the Le mec amd JA board the seqencer is running, but the left screen just shows “card…” and the right screen is garbled (not the same each time). My SD card is 32GB which i now see from the documentation may be a problem. Will try to get my hands on a smaller one tomorrow 🤞

17703227d9536da1

Garbled screen output could also be dodgy cables there, including a loose end of the cable shorting with itself or on the OLED PCB. Check that there is actually a jumper on J15_S shunted to 3v3 and that the surrounding resistors R33A/B/D/C are mounted, also that R33D is 560R.

dcbf84ceef5b5704

latigid on I have just finished assembly, double checking everything is working after each step, and now have a fully working MIDIbox SEQ v4+. Thank you again for your help!

dcbf84ceef5b5704

J15_S - there it is !! 😁

So I’d missed that entirely. After adding that jumper in place both displays are working corrctly. I think the issue with the SD card was a red herring- somehow even without that jumper it was managing to partially print “Searching for SD Card…” during the boot process, and then the displays were freezing- but actually there was no issue with the SD card, just the displays.

All seems to be working now so about to start re assembling in the case…

17703227d9536da1

Well done!
Serial number is here if you want!