Custom Flex PCB sensor extension

I have manufactured a custom flex pcb with Hirose connectors to a custom board of mine with openmv h7plus hardware.

We use the original OMV global shutter sensor for our application .

First production run we manufactured a pcb which is tripped the size of the one OMV sells and it worked perfectly.

In a second production run we made the pcb half the size because it was too long (mechanical fit in our device).

The OMV is unable to connector to the board . Wither when I connect with the IDE there is no sensor detected or when I run a script an exception is thrown at sensor.reset() or sometimes even at import sensor.
The design of the longer and shorter PCBs are identical and made by pros . Impedance is controlled etc.

Pin to pin checks out.


  1. any idea of what the problem can be the flex pcb since you have manufactured them yourselves as well
  2. are there software checks upon init that are maybe too aggressive (i.e. frequency check just slightly out of range or voltage )

Thanks a lot.

Yeah, the sensor detection runs at 100 KHz. So, very slow. If that’s failing you almost certainly have an electrical/connector issue.

snapshot() having an issue is different. That’s higher speed. But, if sensor detection fails on bootup it means just the voltage rails to the camera or connector is bad.

Thanks. Is it possible to readout the voltage sensed by the board from the ide?

Strange thing is that with the longer PCBs (I have 20 of them) there is no issue.

With the shorter ones (30 of them ) there’s always error at init . Can I readout manually the parameters which are causing the board to fail?

Can I change the check values in the firmware at init?

I’m quite perplexed since with the longer pcb I can work at hqqqvga at 370 fps but the shorter one (less susceptible to impedance imbalance ) I can’t.

The pins are all digital I/Os. You could edit the firmware to get their logic values. But, our software is quite robust. The issue is most certainly the board/connector and or voltage supplied to the camera board.

It’s not the length. Sensor detection runs at 100 KHz. It would work even if the board was a meter away.

Understood . Is the pinout of the global shutter you provide correct?

It could be that the designer of the longer boards didn’t use the schematic / layout of the global shutter board but I’m sure we did for the shorter ones.

All the NC pins on your layout are not connected on the shorter ones.

Our designs on the board repo haven’t changed in years. openmv/openmv-boards: OpenMV boards, schematics, and layout (

It’s all correct. I’d just double check the schematic and their layouts.

Will do , again, as you never know :). Thanks for the precious tips.

I probed 3.29V (VAA) on C5 and 3.12V on C2 (VCC) with the non -functioning FlexPCB and similar with functioning. Pinout has to be correct. Connectors are identical part numbers on both long and short flex PCBs.

Tried with two different camera boards. Not the best multimeter and probes.

Will have someone check the schematics and layout . Must be something funky going on there that I can’t see.