PWM Output Waveforms From Spektrum Receiver

     I am trying to write Arduino code to read PWM signals from Spektrum receiver.  Decided to examine and document the receiver output waveforms with an oscilloscope and video camera. Thought this information might be of some value to others trying to do the same thing.

Throttle Channel PWM.jpg

Elevator Channel PWM.jpg

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  • Hi Dave,

    I'm very new to electronics.  Bearing that in mind, could you provide, or refer me to, a circuit for getting an arduino to read PWM from a standard servo receiver?  You refer to resistors above.  Can I provide 5V to the receiver from the board?  Then 150 Ohm resistor b/w channel pin and receiver signal to pull down.  Does your "plus V+ und GND of course" also refer to the need for resistors?  Or is only the single pull down required?


    • I think this one can suits your needs:


  • Hi,

    I'm interested in this thread as I'm working on an Arduino based sound system for my Spitfire. So far I have got an Adafruit wave shield to go with my Arduino Uno, and have it working using a sketch that changed the interupt, enabling change in engine speed by an analog pot control - this works. However, I have started thinking about how I could use the servo output waveform to drive a digital Arduino pin - actually analog pin A0 - to control the rate proportionally with the throttle.

    The info here is good in that it shows the waveform and timings, however, I have no clear idea how to use this to control the Arduino interupt. Has anyone had any experience of this?

    If there is no obvious way, I may have to drive a servo in parallel with the throttle to turn a pot, which then controls the interupt. This will work, but is not at all elegant and adds weight when I don't need it.

    I would really like to sort out the digital method and then pass it all on to other interested people.

    Can you offer any clues please?

  • Very nice! really!

    Could you just confirm me that the max voltage for these channel is 3 volts???

    Since I don t have an oscilloscope but a logic analyser, I cannot read those values.



  • I think the killer set-up tool for RC/APM checkout would be a box to plug in the APM input cable. It should give bargraph output of each RC channel. That would let someone confirm their RC/APM wiring was correct before ever introducing the APM.

    I just went through a APM2.5 setup and thought how cool that gadget would be to have.

    Stock out of the box APM requires the firmware upload first before even connecting to Mission Planner before you can start RC calibration.

    This just goes to show you that there are very few ideas that are unique.


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