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  • Bela Mini - No midi over USB A port unless micro USB port used?

right, so no software workaround possible. The deal involves a hardware hack:

  • with a wire cutter, carefully clip P1.07 ( usb1 VI) between the PocketBeagle and the BelaMini cape. The closer you are to the PB the better.
  • bend the leg out to ensure it does not short together again

For example:

alt text

Option 1:

  • use a jumper wire on the BelaMini headers to connect any of the VOUT pins (P1.24 or P2.13) to P1.07 (this is also displayed above, where the blue wire is jumpering P1.24 to P1.07)
  • once everything work fine, cut off the bent-out leg of P1.07

Option 2:
- use a piece of wire to make the same connection as in option 1, soldering at both ends. This is tricky in that you'd have to take the signal from the bottom of the PB (e.g.: from P1.24), and route the wire somehow to the bent out leg of P1.07.

    giuliomoro right, so no software workaround possible. The deal involves a hardware hack

    Got it! I think Option 1 will work for this project. The pots and footswitches are connected via solid core wire to the pin headers and I haven't had any issues with loose connections - so I imagine this jumper will be fine as well.

    Thanks again for all your help with this! I will do a test tonight with my set-up and confirm that it works on my side as well and then I will mark as solved.

    Any chance this fix will make it into the next Bela hardware revision (Is there an upcoming hardware revision?)

        kreiff Any chance this fix will make it into the next Bela hardware revision (Is there an upcoming hardware revision?)

        Yes, but this is not going to happen very soon, as we just got a large amount of boards delivered from the factory ( which is actually sad, given this discovery 🙁 ).

            giuliomoro we just got a large amount of boards delivered from the factory

            Oh, Bummer! Well, at least the fix is pretty easy. I'll definitely keep a lookout for the next revision, though.

              @giuliomoro - Had a chance to test this out tonight - it works! clipping the connection between Bela and the Pocket Beagle at P1.07 and then jumpering P1.24 to P1.07 gets the USB A to work without the micro USB being plugged in and I can power it from the VIN pin using my step down board.

              I am still experiencing the issue where having the USB A cable plugged in prevents the board from powering up via VIN. I know you mentioned being unable to reproduce this issue. For now - I will chalk it up to maybe some kind of residual damage from powering through VIN and micro USB at the same time.

              I'm going to order a fresh Bela & Pocket Beagle and see if I can reproduce - but I will save any results from that test for another thread!

              Thanks again for all of your help, Giulio!

                kreiff I am still experiencing the issue where having the USB A cable plugged in prevents the board from powering up via VIN. I know you mentioned being unable to reproduce this issue. For now - I will chalk it up to maybe some kind of residual damage from powering through VIN and micro USB at the same time.

                there should be no damage occurring from powering up from VIN and micro USB at the same time: the power management IC will switch between the two as needed. Especially with the USB power pin cut, I don't see where this problem would arise from. If you have an UART adapter (or you can make one with a PB), then it would be good to look at the output of UART0 (RX: P1.32, TX: P1.30) during boot.

                    kreiff d then jumpering P1.24 to P1.07 gets the USB A

                    forgot to mention: the current on P1.24 is limited to 500mA. If you are using some current-hungry USB device, you may want to connect to P1.07 to VIN (P1.01) instead. However, in that case the USB device will not be powered when you are powering the PocketBeagle via USB micro.

                        giuliomoro here should be no damage occurring from powering up from VIN and micro USB at the same time: the power management IC will switch between the two as needed.

                        Good to know!! This was something I worried about - so I'm actually really happy that this is a feature.

                        giuliomoro it would be good to look at the output of UART0 (RX: P1.32, TX: P1.30) during boot.

                        Should I just pull the log with dmesg -w while booting up with P1.24 and P1.07 jumpered? It doesn't even flash when a USB A cable is plugged in - so I can't really get any info about potential issues with the cable plugged in unless I plug it in after the Pocket Beage boots. Just want to make sure I'm looking at the right log at the right time.

                        giuliomoro the current on P1.24 is limited to 500mA.

                        Good to know! I don't think this should be an issue for me - all of the devices I'm working with have their own power supply. Even from a UX perspective I think 500mA coming from a guitar pedal acting as a USB host is pretty generous.

                                kreiff Should I just pull the log with dmesg -w while booting up with P1.24 and P1.07 jumpered? It doesn't even flash when a USB A cable is plugged in - so I can't really get any info about potential issues with the cable plugged in unless I plug it in after the Pocket Beage boots. Just want to make sure I'm looking at the right log at the right time.

                                No, you'd have the UART adapter plugged on your computer, and looking at the serial data over a screen (in my case I do: screen /dev/tty.SLAB_USBtoUART 115200), and see if anything shows up there.

                                Does the PWR LED turn on or nothing at all? If it doesn't, then probably the serial port would say nothing at all :/

                                    giuliomoro No, you'd have the UART adapter plugged on your computer, and looking at the serial data over a screen (in my case I do: screen /dev/tty.SLAB_USBtoUART 115200), and see if anything shows up there.

                                    Got it! That makes sense.

                                    giuliomoro Does the PWR LED turn on or nothing at all? If it doesn't, then probably the serial port would say nothing at all :/

                                    The PWR LED does not turn on. I get a very quiet popping sound if the headphone jack is plugged in when the barrel jack is input - but after that, nothing. No LEDS on the Pocket Beagle or Bela.

                                    I will try to see if the quiet popping sound triggers anything - but I agree, it's unlikely. Either way - I have put in an order for a new board to see if it is just my test board (that has been through a lot, honestly). But I will report back with any output from UART0.

                                        9 days later

                                        Hi @giuliomoro
                                        Got my fresh Bela yesterday and got it on my test bench today.

                                        It does seem like my old Bela has some issue that the fresh one does not. They both exhibit the issue I noted earlier where powering from VIN and grounding via a System ground (i.e. P1.16, P1.22, P2.15, P2.21) while a USB A cable is plugged in prevents the board from powering on / booting up.

                                        Strangely - If I use the Analog Ground (i.e. the ground pin socket adjacent to P2.17 on the ADC row) with VIN - my fresh Bela will power on / boot without issue with or without a USB A cable. My old one will not...So, this solves my problem for now.

                                        I will also note this is only an issue using the voltage step-down. If I use an apple USB charger with a cable stripped to bare wire on one end and just plug the 5V and Ground from that into any ground it will power on / boot. So, it is somehow related to the step-down...but I'm not entirely sure how. If you've got any thoughts there I would be interested in hearing what you think the causation might be - but regardless, I think this is officially solved for me.

                                        Thanks again for all of your help!!

                                        I have no idea. Given how this seems to be a PocketBeagle issue, a better place to ask would be this one