I am starting this discussion to post information for  testing the Px4 platform.

Most of the discussion is currently in the APM vs Px4 thread. ArduCopter on the Px4 is a work in progressand has made great progress. I have Arducopter on a Px4 Fmu board hovering now and I am very glad to see the code base integrated into the Stm32 platorm. Ardupilot represents many hours testing and refinement , many thanks to Andrew Tridgell ,Randy Mackay  and the other developers as well as Gary Mcray for the documentation  on the Wiki

The Px4 can support a Quad with 4 Motors using only the Px4_FMu board with some of its Usart pins defined as Pwm outputs or using the Px4_Io board to supply Pwm motor (servo) outputs. The configuration with the Io board may work better at the moment , the Fmu only has a number of issues to get booted up  configured and running. It may be that all the testing at the moment is being done with boards that use the Px4_Io.

The Px4  usb is software driven not a ftdi chip like the Apm and has given problems but is working now . When the Stm32 bootloader starts it creates a Usb port with its own Id and sets up a DFU device for loading. If no bootloader request is received it jumps to the code startup and creates a usb serial port with a different USB Id for a mavlink connection. Windows drivers have to deal with the Usb connection and connect the appropiate driver.

I think the Px4 vs Apm  answer is that it is still early in the Px4 development but shows great promise.





Views: 14576

Reply to This

Replies to This Discussion

You have to power cycle the board after loading the code before you can connect with MP.

Yes Craig, I didn't mention that but I did, even a dozen of times. Also restarted MP and PC and changed the sequence of connecting/restarting to test all of them. Every time the serial port shows up in the device manager (W7/64 ultimate)

Didn't check if connecting using the 3dr radio's works. I'm in the middle of rebuilding the quad, so when it's ready I can test that as well and hopefully prove the program is at least running.

Hi All, 

I have been experimenting with my full up PX4 and have found a possible issue when using the USB to power the full up PX4.

When powering the full up PX4 through the USB connection I have been using a powered USB hub and for good reason. If I try to power the full up PX4 with just the USB connection, it will not communicate with the MavLink connection though all of the leds appear as they should.

When powering the full up PX4 with a powered USB connection I can communicate with MavLink with no problem. However the GPS number of sats will drift all over the place from 0 to 5 and back down to 0. A measurement of the voltage being supplied to the GPS indicated an out of spec 3.96 vdc.

When powering the full up PX4 with a battery though the power converter, the GPS will get a solid lock of 7 sats or more indoors and the voltage supplied to the GPS is around an in spec 4.95 vdc.

 When I say full up PX4 I am including the FMU, IO, GPS, Spektrum PPM R/C satellite receiver, and outboard compass. I am supplying the power converter with a 7.2 vdc NiMH battery.

When powering the PX4 with a battery through the power converter I do not feel that 4.95 vdc is sufficient as it does not leave much margin.

Has any other member experienced this phenomenon? 


TCIII ArduRover2 Developer

Do you mean internal PX4 power converter or BEC?

USB alone is not enough, garanteed ;-) I see it on the PPM encoder.

I use 3S lipo connected with balancing cable to PX4 together with USB to APM planner.

Servo channels between PX4 and ESC I keep unconnected with APM (annoying beeping othervice, when not armed)

In flight I use battery connected to Q Brain (HK) and balancing cable to be sure(?)

Some 0.05s glitches with radio though, but otherwise ok.


Yes, I am referring to the power converter that is on the PX4 IO board.


TCIII ArduRover2 Developer

Need some advice. What is the Basic board or two that need with PX4 to get a quad, hex or octo flying. Thanks Roman Flying Apm 2.5 presently


This Arducopter Wiki guide may be of help: http://copter.ardupilot.com/wiki/px4fmu-plus-px4io-wiring/



The  Px4 Fmu  board   processor package  has a low pin count  and limited  number of lines for  input and output.   The Fmu only  configuration  uses the Usart 2  lines  as  Servo outputs  for a Quad configuration.   To drive  more than 4  motors  you have to have  the IO board expansion to get drivers for  hex or octo  , it also has an inverter  for subus , status leds   and arming switch function

With Fmu only  their is no status led output on the fmu board only the blue running led

No current sensing  input  but could probably be accessed .



@chester, i tried setting the battery voltage to actual voltage on the battery using MP. but when i switch the tab the figure resets  to '0'. this is when selecting 'Px4'.

Maybe latest MP have changed something. I didn't update and fly my px4 for month maybe more(building skywalker 168 for long range) so I can't help you in this question.

Reply to Discussion


© 2018   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service