Px4flow works alone but not with pixhawk 4


Hi! My issue is with latest build (maybe with previous builds as well not tested though). I’m using pixhawk 4. And tested with 2 different px4flow sensors (one with sonar and other without).

Connecting px4flow sensors to QGC directly shows they are working well and gives good quality for my floor surface (above 250).

As I integrate one of them into the drone I see only temperature values changing in OPTICAL_FLOW_RAD as well as distance for the model with sonar and time values. All other values are zeroes (integration_time_us, integrated_{x,y,{x,y,z}gyro}). Even sensor_id is zero. While when I connect px4flow directly to QGC I see sensor_id is not zero.
Not only MAVLink shows those values. Reading uORB messages with

listener optical_flow

gives same results.

Btw I’m using additional LidarLite sensor for distance measurement in PWM mode. It provides correct readings which are observed over MAVLink or directly reading uORB messages with listener.

I’m trying to run without GPS.

My config values are:

param set SENS_FLOW_MINHGT 0.3
param set SENS_FLOW_ROT 4
param set EKF2_AID_MASK 2
param set EKF2_RNG_AID 1
param set EKF2_HGT_MODE 2
param set SENS_EN_LL40LS 1

Could you share the Windows driver for this? I just got one and no luck connecting to MP or QGC.


I have not installed any specific drivers on my windows 10 machine except from what installer installs. And all things are working out of box. Also now I’m mostly running this on Linux. No issues as well. The only issue is Modem Manager which I have to turn off to get Firmware upgrade working without interrupts. But this has a drawback of loosing LTE connection on my laptop.


Just will leave it here if somebody faces similar situation. Neither px4flow nor lidar lite range meter where working via i2c on my configuration. I was able only run lidar lite in PWM mode. While px4flow worked only directly connected to pc via usb or if connected to battery powered drone was sending a couple of measurements and then became silent. The issue was with power supply voltage. It was about 4.8 V provided by pixhawk 4 power module. When powered with external power source all problems are gone. px4flow works reliably. lidar lite works in i2c mode.