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Can't failsafe with PPM encoder in the loop

Posted by Euan Ramsay on June 3, 2014 at 2:10am

Hi guys,

 

A strange one this. Been testing my failsafe on the bench, and noticed a problem.

 

Relevant Setup:

Pixhawk (3.1.5)

PPM encoder v2 (factory defaults)

http://www.buildyourowndrone.co.uk/8-channel-ppm-encoder-version-2.html

Spektrum and/or Orangerx radio rx.

Spektrum DX8

 

My procedure:

1. Set radio/throttle failsafe to RTL (PWM signal is default - 950?)

2. Arm and spool up the motors on the bench in stabilise

3. Turn off the DX8

4. The motors start to "pulse"

5. *No failsafe is running*. Stays in stabilise

6. Unplug the PPM

7. Failsafe now works perfectly.

 

Synopsis: The PPM encoder is not passing through PWM=0 to the pixhawk.

 

What do I need to do to get the PPM to failsafe properly?

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Replies

  • Mauricio September 15, 2014 at 8:32am

    Hi Euan, did you get this resolved? if yes, how?

    • Euan Ramsay > Mauricio September 15, 2014 at 10:22am

      Yes. Turns out it was Spektrum causing the problem. I set the trims to 150% and rebound it, so the minimum throttle was 900 pwm. I set it back to 100% for normal use, and calibrated the APM at that. Worked out fine - the PPM encoder used the 900 pwm as the minimum value, causing the failsafe to activate.

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