MAVLink OSD with Matek H743

A guide for how to use the matek H743 in conjunction with a cube orange plus to get analog osd

Flashed with a custom ardupilot firmware, we can use the matek to draw the osd on the analog video feed using mavlink telemetry data from a cube orange plus rather than its own internal information.

Note that we hook up the vtx control pin to the cube orange plus so we can still control the vtx power with the rc.

Custom ardupilot build

The matek needs a custom build of ardupilot to be able to display mavlink telem info on the osd. The cube does not need custom firmware.

1MB

arduplane.apj

Open

Flash your matek with this build then configure the parameters as follows:

Parameter	Value	Purpose
SYSID_THISMAV	42	Keeps the Matek from using the same MAVLink system ID as the Cube
OSD_TYPE	1	Enables the onboard MAX7456/AT7456 analog OSD
OSD_REM_ENABLE	1	Enables remote MAVLink telemetry for OSD panels
OSD_REM_SYSID	1	Accepts telemetry from the Cube's MAVLink system ID
OSD_REM_TOUT	1500	Marks remote telemetry stale after 1500 ms
SERIAL5_PROTOCOL	2	Enables MAVLink2 on the Matek TX8/RX8 port
SERIAL5_BAUD	57	Sets the Matek TX8/RX8 port to 57600 baud

Reboot the Matek after changing serial parameters.

Feel free to use any serial port. I used TX8/RX8 because the others were broken on the matek I used.

Cube Orange Plus Params

These params need to be changed on the cube orange for this to work. You can use any two serial ports on the cube, but you do need two separate serial ports, one sending telem data to the matek and one to control the vtx.

Parameter	Value	Purpose
SERIAL2_PROTOCOL	2	MAVLink2 output on Cube TELEM2
SERIAL2_BAUD	57	57600 baud to match the Matek

Set the Cube stream rates for the telemetry port wired to the Matek. For TELEM2, use:

Parameter	Value	Purpose
SR2_EXT_STAT	5	Sends battery and system-status data
SR2_EXTRA1	10	Sends attitude and flight display data
SR2_EXTRA2	5	Sends additional flight telemetry
SR2_POSITION	5	Sends global position and altitude data
SR2_RAW_SENS	2	Sends GPS/sensor status data

And lastly ensure the cube is set up for vtx on:

Parameter	Value	Purpose
SERIAL3_PROTOCOL	37	Configure gps1 serial uart to control the vtx
VTX_ENABLE	1	Enable vtx control from cube
RCx_OPTION	94	Map vtx control to an rc switch

You might need to also configure VTX_POWER and VTX_MAX_POWER to allow for correct power switching.

Nadir camera switching

This feature only works on custom, experimental builds of gryphon

You can also plug in the raspberry pi 5's j7 pins into the matek and configure it to switch between the front facing and nadir camera views.

Update this parameter on the orange cube plus:

Parameter	Value	Purpose
SR2_RC_CHAN	10	Sends rc information for vtx camera view switching

Then update this on the matek:

Parameter	Value	Purpose
OSD_REM_CAM_CH	7	Which rc channel to look at for the camera switching

The pi will send analog composite video on j7, and the matek will read the rc switched and update the displayed camera feed, c1 or c2, depending on if the switch is high or low.