Before you start
- The pinout diagrams for the exact flight controller, camera, and video transmitter.
- Confirmation that the video system is analog rather than DJI, HDZero, Walksnail, or another digital system.
- Propellers removed and power disconnected while checking or changing wiring.
Safety checks
- VIDEO, CAM, VIN, and VOUT carry an analog image signal. Never connect them to an ordinary UART TX or RX pad.
- A pad labelled VTX may mean analog video output to the transmitter, not a UART. Verify the board pinout before wiring.
- SmartAudio and IRC Tramp control VTX settings; they do not carry the camera image.
Steps
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Identify the three signal types
VIDEO/CAM/VIN/VOUT is analog video, UART TX/RX is digital serial data, and SmartAudio or Tramp is a digital control connection for VTX settings.
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Wire the camera video into the flight controller
Connect Camera VIDEO to the flight controller CAM, VIN, or VIDEO IN pad, then connect camera power and ground according to the product pinout.
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Wire the flight-controller video output to the VTX
Connect the flight controller VOUT, VIDEO OUT, or analog VTX pad to the video input on the transmitter. The video remains analog while the flight controller adds OSD information.
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Connect optional VTX control separately
If the transmitter supports SmartAudio or Tramp, connect its control wire to the UART TX or dedicated control pad specified by the manuals. This wire controls channel, frequency, power, or Pit Mode only.
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Diagnose OSD without a camera image
If OSD text is visible on a black background, the flight-controller-to-VTX path is probably working. Check camera power, camera VIDEO, ground, and the flight-controller CAM/VIDEO IN connection before changing UART settings.
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Use a direct-video bypass test when needed
Temporarily connect Camera VIDEO directly to VTX VIDEO. If the image works directly but not through the flight controller, inspect the flight-controller video input/output wiring and analog OSD circuit.
Troubleshooting
VTX VIDEO was connected to a UART TX/RX pad
Move the video wire to the flight controller's analog VIDEO OUT/VTX pad. Use UART only for SmartAudio, Tramp, or another documented control protocol.
The camera works when connected directly to the VTX but not through the flight controller
Check CAM/VIDEO IN, VIDEO OUT, shared ground, the board's analog OSD hardware, and any firmware setting specifically related to analog OSD.
A digital VTX also uses UART and the wiring seems contradictory
Digital systems may exchange OSD or control data over UART/MSP, but their video path is handled inside the digital system. Follow the digital VTX manual rather than the analog wiring path.