Pixracer doesn't se radio channels

A good day,
I’m a newbie in the drone world and I’m building, like so many others, my own drone.
I bought a pixracer as my controller and al the other components. After i received everything I started building the machine.
Because I bought a flysky th9x with receiver with no ppm out capabilities I have a pwm to ppm encoder. This is where the trouble begins

I configured my radio and connected the receiver to the encoder. Both are powered. The led on the receiver is solid red and the led on the decoder is blinking. And when I increase the throtle the led on the encoder starts blinking faster. Just like it should do. But when I start qgroundcontrol and connect the pixracer it doesn’t show me Anny channels. So I’m stuck now and I don’t know how to fix the problem. Is there someone out there who knows what I’m doing wrong? Or haves a suggestion what I could do tho fix it.

Thanks for the help. , Sander.

Looks pixracer did not recognize the receiver/ppm encoder, if your remote and receiver are properly paired. Try another encoder, if you are confident about your pixracer’s RC input.

When i connect my receiver directly to a motor it just works so i’m pretty sure that my radio is paired correctly. I don’t have a other encoder. Else I would have try that. is there a way to test the RC input? I do not have a oscilloscope. Or could het be that I misconfigured my radio?

To test the “RC INPUTS” in QGROUNDCONTROL, simply go in “WIDGET” --> ANALYSE.

then, in filter, bottom left, type “RC”
then, you will see RC RAW with channel # and you will see if it sees the PPM stream and every single channel separately.



Thank you for your help.
I just did that, there is nothing to see. Just a flat line.
Thank you for your help.
Greats ,

I re uploaded the filmware.
Now when I go to analyse and I searched for “RC” he doesn’t see anything. There are no results.

Is that normal ?

Thats not normal of course. But still can’t tell exactly the problem. Encoder still be the top suspicious, while there do have a chance your pixracer board RC input port damaged. Will be easier to have either another encoder or another flight controller to verify it.

I was starting to think that my controller is broken. But i was testing some things and I discovered that when you plug-in the GPS I see the raw data and channels. But when in disconnect the GPS those data disappear from the ANALYSE list. So I still hope that it is the decoder that is buggy or broken and not the PIX.

I ordered a new decoder from a different supplier this time. In the meantime I’m looking for someone close to me with a working encoder or a PPM supported receiver. Douse someone now how sensitive the PPM protocol is to the wire length?

With a Arduino I made a PPM generator. Now I can see 8 nice channels in the radio section of Qgroundcontrol. Now I also see 8 RC channels with the “Analyse“ utility.
I now know that my PIXRacer is alright.
So there must be something wrong with my PPM encoder or with my remote settings.
I also analyst the ppm signal witch is coming from the encoder with a Arduino. I do gat signals and they change when I move the sticks. So I’m going to find out if I can re program the encoder and if the values witch are coming from the encoder are theoretically usable by my controller.

I think I found my problem.
I DIY a little oscilloscope to analyses the signals. It looks like the signals from my decoder are inverted.

Red: generated signal (working) green: Signal from decoder (not working)


you are amazing :slight_smile: