Subject: Frame Dropping with PMD TOF LIOW2 (M0169) on VOXL2 Flight Deck - Royale SDK Warnings Persist After Troubleshooting
Hi ModalAI Community/Support,
I'm working with a VOXL2 Flight Deck and trying to integrate the PMD TOF LIOW2 sensor (part number M0169). Originally, I removed the hi-res camera from J7 Upper and connected the TOF there, but after advice, I switched it to J6 Lower and disabled all other cameras. Unfortunately, I'm still seeing severe frame dropping via Royale SDK warnings in the voxl-camera-server logs.
Setup Details:
Hardware: VOXL2 Flight Deck + PMD TOF LIOW2 on J6 Lower (flex cable checked and reseated). I'm using the dual cable which was previously used by the tracking and hi-res cameras.
Software: voxl-sdk is 1.5
No other cameras connected/enabled.
Power: Stable bench supply (5V/3A+).
What I've Tried:
Connected TOF to J7U initially (camId:3), saw drops.
Moved to J6L (camId:0), disabled all other cams—same issue.
Updated config to minimal TOF-only (tried FPS 15/20/5, decimator 1/2, pre_height 172/180/1629, exposure max 2000-3000).
Ran voxl-configure-cameras and selected a TOF preset (e.g., C-26 or similar).
Checked for overheating: Monitored temps via VOXL Portal/voxl-inspect-cam -a—[add your temp readings here, e.g., ~50-60°C with heatsink?].
Debug mode: voxl-camera-server -d 0 to list modes.
Updated SDK via apk update && apk upgrade (if applicable).
Tested in low-light to avoid saturation.
Logs from Camera Server are:
existing instance of voxl-camera-server found, attempting to stop it
configuration for 1 cameras: [TOF config as above]
thread is locked to cores: 4 5 6 7
connected to mavlink pipe
Connected to cpu-monitor
Starting Camera: tof (id #0)
gbm_create_device(156): Info: backend name is: msm_drm
------ voxl-camera-server: Started 1 of 1 cameras
------ voxl-camera-server: Camera server is now running
WARNING: [ROYALE_WARNING] {ROYALE_FRAME_DROP}: Dropped 20834 frame(s).
WARNING: [ROYALE_WARNING] {ROYALE_RAW_FRAME_STATS}: Raw frame drop stats: Bridge 20834 frames dropped, FC 0 frames dropped, 9 frames delivered.
WARNING: [ROYALE_WARNING] {ROYALE_FRAME_DROP}: Dropped 9 frame(s).
WARNING: [ROYALE_WARNING] {ROYALE_RAW_FRAME_STATS}: Raw frame drop stats: Bridge 9 frames dropped, FC 0 frames dropped, 171 frames delivered
The initial massive drop (20k+ frames) happens on startup, then smaller ongoing drops. No frames are usable in apps like VOXL Portal or downstream pipes.
Has anyone encountered similar Royale bridge/FC drops with this TOF module? Could it be related to using the dual cable from the tracking/hi-res setup? Maybe a cable mismatch, firmware issue, power ripple, or faulty hardware? Any specific config tweaks or SDK versions that fixed this? Appreciate any insights!
Thanks,
