PX4Flow module problem?

Got Copter 3.4 on the quad copter (latest). Using a pixracer and PX4flow optical flow + maxbotics sensors. I hook everything up and I configure it but the FC doesn’t show any flow information or range. I’ve loaded the firmware for the px4flow board and done the focus test.

I can hear the sonar clicking when i hook it up via USB, but when it’s just powered it doesn’t do anything. Lights come on, led’s flash but nothing on the FC logs.

Has anyone gotten a px4flow module working on a pixracer? What can i test/try?

Also I read that you have to set the offset to -9000 degrees or something because the standard board orientation XYZ icon puts it sideways? Any comments?


I’m sure you have but just in case, you’ve followed all the instructions here of course? http://ardupilot.org/copter/docs/common-px4flow-overview.html

And you’re using the Mission Planner to do the configuration?

Also note that we can’t use the px4flow’s sonar because it’s very short range. Instead a separate range finder like the Lightware SF10b is required. Sorry, but it’s really a hardware issue!

Is there any benefit to using the PX4Flow in addition to a GPS as opposed to replacing it. I would like to use the PX4FLOW at low altitudes for more precise maneuvers for example. Will the Sonar work at all or has it been written completely out of the code?

Hi Marty,

If you expect that where you use your copter it will have bad GPS reception then it might be best not to use it. If in the other hand you’ll have good GPS but want to enhance it with optical flow, then the EKF is capable of using the best of two worlds.

@rmackay9 will need to confirm but I think the sonar is still supported. It’s performance is bad though, which why it is advised to use a Lidar instead.

That’s good news… I will give it a try on my Heavy Octo… outside as an enhancement to low altitude position hold and landing.

Later this winter, I will move it to my Nitro powered Single copter experimental build… that should be a costly fiasco but fun nonetheless.

Thanks for your comments.


I’m afraid that we don’t support the sonar on the PX4flow sensor. It’s not a huge amount of programming to add support but it also performs so badly that I personally haven’t prioritised getting it working.

I have a spare Maxbotix I2CXL MB1242. Will this rangefinder work with the px4flow or do I really have to buy a laser rangefinder?

It will work with any rangefinder ArduPilot supports. With a sonar probably won’t be as good as it would with a laser rangefinder.