OAK4D HW sync issues

jingnan

Hi team,

We are testing HW sync with the adapter and running the official example: luxonis/depthai-coreblob/main/examples/python/Misc/MultiDevice/multi_device_frame_sync.py

While it runs at first, after a few seconds it will lose sync and print the following error messages:

Sync error: Sync lost, threshold exceeded 2106.000029016286 us
Sync error: Sync lost, threshold exceeded 2106.000029016286 us
Sync error: Sync lost, threshold exceeded 2106.000029016286 us
Sync error: Sync lost, threshold exceeded 2106.000029016286 us
Sync error: Sync lost, threshold exceeded 2106.000029016286 us

We are using the latest DepthAI v3.8.0 and the Luxonis OS version on the devices are 1.35.0

Oskar-Luxonis

Hey jingnan - this looks like the example is comparing end-of-exposure timestamps, while FSYNC synchronizes the start of exposure. With auto-exposure, cameras can have different exposure durations, which can produce the 2 ms difference you see.

Could you change CameraExposureOffset.END to CameraExposureOffset.START in the example and try again? If it still loses sync, please share the output and your device IDs.

Thanks,
Oskar

jingnan

@Oskar-Luxonis , thanks for the note! It turns out that with the cables we bought (with R3 on them) from the online store work with FSYNC, but the cables that came in the adapter boxes don't work. Have you guys seen something like this before?

Oskar-Luxonis

Hey jingnan - yes, we have seen this with older M8 cable revisions. The R3 cables improve FSYNC reliability on OAK4, so please use those for this setup. I can check about RMA/replacement for your old cables if you want.

Thanks,
Oskar