I followed the document PX4FLOW Developer Guide, connected QGroundControl to PIXFLOW finally.
The picture above is output ofOPTICAL_FLOW.flow_x and flow_y
I have some questions when start:
Q: Connect Pixhawk or PX4FLOW to PC when upload firmware?
A: Connect FX4FLOW to PC using USB
Q：VIDEO_ONLY set to 1, butVideo Downlink in QGroundcontrol can’t show PXFLOW’s video output (use it to adjust focus only)
A：upgrade QGroundcontrol to version 2.2 or up
Q：What is focus range PX4FLOW?
A：I did a test, the result is 0.4 – 0.8m.
( remark: document recommend to set the focus to 3m, I can do it by adjusting the lens of PX4FLOW )
Q：How to wiring to Pixhawk?
A：Connect PX4FLOW UART3 to Pixhawk’s serial port. Default id TELEM2
Finally I did a outdoor flight test, check here.