• Hardware

  • OAK-D W PoE - USB 2.0 M8 8 pin to 4 pin cable

Hey there,

To provide some context beforehand:

We are using oak-d w poe cameras for a current prototype we are doing. We are able to communicate with the camera using USB (we forced the firmware to be in USB boot), using the usb to m8 programming board, from our system. All works great so far.
Now, we developed a custom cable that should connect an m8 4 pin output (this is an usb 2.0 from our system) to the m8 8 pin input of the camera. Our cable is not working at the moment and it is unclear why.

So, the real questions are:

  • We know that the OAK-D W PoE works using usb2.0. This was verified and confirmed using the adapter board and our system. By that logic, we should only need the PIN 3,4,5 and 8 of the m8 connector, right?
  • Do pins 1, 2, 6 and 7 need to have any default values? Should they be connected to VIN or GND?
  • Maybe the pins 3,4,5 and 8 need anything else, besides straight connection ?

Best regards,

Hi @alexandrepires
This should be working, the pins are correct. Could you recheck the cable? Might be a hardware issue somewhere, or a bad contact perhaps(?)

Thanks,
Jaka

    Hello jakaskerl ,

    Thanks for the answer. If we just need pins 3,4,5 and 8, then, most definitely is a contact or broken cable issue. We will check it Monday and provide feedback here.

    Thank you and have a nice weekend,

    Alexandre Pires

      a month later

      Hello @jakaskerl ,

      The issue has been somewhat stale, since we ordered cables that are robust and applicable to industry settings, and we were waiting for some samples to arrive.

      We tried several ways and its not working. It only works with the usb to m8 board. I have the schematic here, perhaps it is possible to see what is actually wrong and what are we missing?

      I hope to hear any idea soon, as it would be really helpful to have this.

      Best regards,

      Hi @alexandrepires ,
      We apologize for the delay. So we have the M8 programming board on our github:
      luxonis/depthai-hardwaretree/master/NG6013_M8_programming_board

      So if your OAK POE device has latest bootloader (0.26), it should be able to boot via USB directly, and your cable only needs to supply power and connect USB2 lines. Also note that 5m long cable USB2 cable (what you are essentially doing) might not work due to EM interference, especially if USB2 lines aren't twisted + shielded.

        Hi erik ,

        Thanks for the support! Ok, we notice that our manufactured cables are not twisted, but they are shielded. We are going test by twisting and removing the length of the cable, just to discard the issue, and, hope that is not related to the our m8 connectors.

        Best regards,

          Hey there erik

          We still have no luck with this. We twisted the USB lines, as well as shorten the cable to be 1 meter and we still have no signs of reading. Could we debug this using only a power supply and check the USB lines output, to see if there is any luck ? Any tips to help debug further are greatly appreciated as well.

          Best regards,

            @alexandrepires could you provide images of this setup? How did you shield/twist the USB pair? Are you sure you connected correct pins? Do you have latest bootloader flashed on the device?

              Hi erik ,

              I attach the images here, to be able to twist(we are twisting only the usb lines), we had the shielding. We cut the cable to be able to remove as much effect possible, perhaps we should make it even shorter?

              The bootloader version is 0.26, using depthai v2.22.0. It should be the correct pins assignation.

              Best regards,

                Hi @alexandrepires ,
                I'd personally try with like 20cm, just to cross out this potential issue (which I still suspect is the culprit). I can't clearly see the pinout, but I trust you checked that too many times anyways🙂

                Actually from the image it seems like pin 3 and 4 (USB+ and USB-) aren't connected:

                  5 days later

                  Hello erik and all,

                  We discovered the issue that we were having and solved it. First of all, do not mind the color of the cables, as it was another test cable we had. It was not from the same provider as in the schematic.

                  The issue was that the pins were mirrored. From your schematic, you have this:

                  After using the m8 programming board and confirming the direct USB pins to M8 8 Pin pinout connections, we verified that the D- and D+ were actually on pins 6 and 7, not pins 3 and 4. GND and VIN are the same, mirrored or not, thats why we didnt see the issue immediately. So, we are assuming that either the usb to m8 programming board is actually mirroring the USB lines or that inside is mirroring somewhat or that the schematic is just wrong.

                  I would recommend to fix the schematic and perhaps add a note what it can happen. (or just link this forum post, as it seems to be covering all bases)

                  We tested with the cables from the provided schematic we gave and now it works without any issues whatsoever.

                  Thanks for all the support! We can close this issue.

                  Best regards,

                    Hi @alexandrepires ,
                    I just double-checked our schematics, and I believe the documentation is correct, see the video below. Could you share some images/videos of the connection now?

                    m8-usb2.mp4
                    9MB