PoE power issues with Oak-D PoE

matthew

Hello, I recently purchased an Oak-D PoE to test for development. The device worked well out of the box for about a day, but now has stopped accepting power from my PoE injector. The PoE injector still works as it powers other PoE cameras just fine, and the Oak-D board itself still works. If I open it up and power it via the USB C connector I can connect to it via Ethernet directly (no PoE injector in the way in this case). What steps should I take for troubleshooting the PoE? The PoE injector is a Linksys LACPI30 that I've used for developing with other Ethernet cameras for quite some time.

Thanks,
Matthew

erik

Hello matthew , as you mentioned this is likely POE injector issue. We do have powering POE devices docs where we mention the required POE injector/switch specifications. I have no experience with debugging POE injectors so I can't suggest much.
Thanks, Erik

matthew

Hello Eric, Thanks for the reply. The PoE injector in question does meet the requirements (IEEE 802.11af support, 30watts maximum output) and did previously work with the Oak-D camera, and continues to work with other PoE devices. Is there a chance I damaged the PoE circuitry in the device somehow? I will try to track down a different PoE injector to test with.

erik

Hello matthew, asking HW engineers internally in case they have any idea.

erik

Hello @matthew , so it would be perfect if you could try with other POE injector(s) as well. Another suggestion was to check LED on POE injector (if it has one) if it detects the POE device. If it doesn't work we will send you a replacement device. Sorry for your troubles.
Thanks, Erik

matthew

So I was able to find another PoE injector around the office, and the good news is that the Oak-D camera does work with this one, so that rules out damage. I'm still confused why the original injector would work a at the start but then seemingly quit.

The original PoE injector does have an indicator LED for when a PoE device is connected, and it was not illuminating suggesting that the devices were not getting along. (this was confirmed by probing VNEG and VPOS on the PCB and seeing only 0.3V)

erik

Hello matthew, thanks for circling back! It's even more strange now - so injector works with other POE devices but not our OAK. perhaps other devices aren't that power-hungry, and there's a problem with the injector that it can't supply the required power?

mikegardner

Gents, I've seen this sort of behaviour in some scenarios with POE. It's a particular challenge with POE switches, for example when the power budget per port seems to be sufficient for the device, but the overall power budget for the switch is being exceeded due to demands from devices on other ports on the same switch, It's worth checking the specs of your POE injector with respect to its power budget. It could be just on the margin of its capability.

erik

Thanks for info @mikegardner ! We will add it to docs🙂