• Bbob

    • Post #1

    I am having trouble getting External Sync working on an OAK FFC 4P with socket A OAK-FFC-IMX378-W and socket B/C connected to OAK-FFC-OV9282-W all with luxonis white flexes connected via USB3 to a workstation. The mono cameras stop running and the color camera occasionally triggers with corrupted frames. I have read forum posts and https://docs.luxonis.com/hardware/platform/deploy/frame-sync/. I am using depthai version 2.29.0.0.dev0+27410ce1be892f0120394bd123ac2f3e103f0a80 and the luxonis provided "depthai\utilities\cam_test.py" script modified to uncomment the sync option "cam[c].initialControl.setFrameSyncMode(dai.CameraControl.FrameSyncMode.INPUT)", set default frame rate to 10Hz and set gpio 6 to output high. The external sync is driven through the PRBS connector pin 6(FSIN) and 7(GND) from an HP33120A function generator which creates a 1.8V squarewave at 10Hz +/- about 1 microsecond of error (jitter plus inaccuracy, verified on a scope) and each camera is receiving the signal at TP2 (FSIN). When no external signal is connected, the mono cameras start up and run at 10FPS, color camera no output. When external sync is commented out, as expected all cameras run at 10FPS, or using the unmodified script - 30FPS. This forum post https://discuss.luxonis.com/d/5323-hardware-trigger-synchronization-including-rgb-image-oakd-s2/20 seems very similar with the same visual artifacts; does external sync work? If so, could luxonis provide a minimal script with 2 mono and 1 color cameras so I can continue to debug the hardware? Are there maximum or minimum pulse width/duty cycle requirements? I have tried 20-50% duty cycles. Thank you.

      4 months later

      Hi bob , sorry for the late reply here...

      I tried both with latest depthai release at the moment (2.30.0.0) and with the above version as well (right on top of 2.29.0.0), I can see the issues (expected) when the sync input is left floating, but the external frame sync works well for me when I provide the signal, pulse/square generated by the Arbitrary Waveform Generator module on a Rigol oscilloscope, 10Hz, 1.8V level (1.8V amplitude with 900mV offset to get in 0V..1.8V range), duty-cycle 10% to 50% (but not important).

      OV9282/OV9782 are very sensitive to the moment this signal is enabled, it's important to have the signal on by the time the streaming is started.
      Jitter or other kind of fluctuations on this signal are generally not acceptable for OV9282, it breaks its internal operations. But up to half a row time should be acceptable the datasheet says, so up to 4us jitter.

      Could you check very slightly changing +/- the frequency on the generator, is it improving?

      I tested with python3 utilities/cam_test.py -fps 10 with this script:
      luxonis/depthai-pythonmain → alex-luxonis:depthai-python:fsync_external_ffc_4p
      These are the relevant changes that also check and properly enable the GPIOs, you can check as well with your FFC-4P board revision:

      cam[c].initialControl.setFrameSyncMode(dai.CameraControl.FrameSyncMode.INPUT)
          # FSYNC setup on OAK-FFC-4P
    script = pipeline.create(dai.node.Script)
    script.setProcessor(dai.ProcessorType.LEON_CSS)
    script.setScript("""
    import time
    import GPIO

    # Script static arguments
    fps = %f

    calib = Device.readCalibration2().getEepromData()
    prodName  = calib.productName
    boardName = calib.boardName
    boardRev  = calib.boardRev

    node.warn(f'Product name  : {prodName}') 
    node.warn(f'Board name    : {boardName}') 
    node.warn(f'Board revision: {boardRev}')

    revision = -1
    # Very basic parsing here, TODO improve
    if len(boardRev) >= 2 and boardRev[0] == 'R':
        revision = int(boardRev[1])
    node.warn(f'Parsed revision number: {revision}')

    # Defaults for OAK-FFC-4P older revisions (<= R5)
    GPIO_FSIN_2LANE = 41  # COM_AUX_IO2
    GPIO_FSIN_4LANE = 40
    GPIO_FSIN_MODE_SELECT = 6  # Drive 1 to tie together FSIN_2LANE and FSIN_4LANE

    if revision >= 6:
        GPIO_FSIN_2LANE = 41  # still COM_AUX_IO2, no PWM capable
        GPIO_FSIN_4LANE = 42  # also not PWM capable
        GPIO_FSIN_MODE_SELECT = 38  # Drive 1 to tie together FSIN_2LANE and FSIN_4LANE
    # Note: on R7 GPIO_FSIN_MODE_SELECT is pulled up, driving high isn't necessary (but fine to do)

    # GPIO initialization
    # IN not necessary, should be default
    GPIO.setup(GPIO_FSIN_2LANE, GPIO.IN)

    GPIO.setup(GPIO_FSIN_4LANE, GPIO.IN)

    GPIO.setup(GPIO_FSIN_MODE_SELECT, GPIO.OUT)
    GPIO.write(GPIO_FSIN_MODE_SELECT, 1)

    period = 1 / fps

    node.warn(f'FPS: {fps}  Period: {period}')
    """ % (args.fps))