Hello! I’m currently running a quad with a pixhawk, PPM Encoder, and AR8100 + Satellite Spektrum receiver. I have setup the the receiver during the BIND process to around 910ish throttle when lost, and it runs around 1000 low throttle when on. I tested this on an APM.
Now with it hooked up this way to the pixhawk, if I kill the radio, the throttle bounces from low throttle (1000) to 973, and continues this loop. It never hits the throttle failsafe.
Question: Is there something in the PPM that sends a default throttle value when there is no receiver signal? Is there something else I can/should double check? Struggling to figure out where to go from here.
I did find this on the wiki, but it still doesn’t explain the bouncing around.
Operation of Failsafe using a PPM Sum Receiver
If the APM is connected to a PPM Sum receiver in pass-through mode (APM input pins 2&3 shorted) the APM’s PPM encoder operates transparently.
There is no independent channel analysis and there is no channel manipulation.
If the receiver is disconnected or the PPM signal is cut off, after a 250 ms timeout the PPM encoder watchdog interrupt will start an 8 channel PPM-PWM generator with the following fail-safe values :
CH1, CH2, CH4, CH6, CH7, CH8 = 1500
CH3 = 900
CH5 = 1555 (flight mode 4)
If an input level change is again detected from the PPM receiver the fail-safe output is terminated and normal PPM pass-through operation is restored.
Alternatively, there is a provision on the APM 2.5 board to fully bypass the PPM encoder when using a PPM-Sum receiver…
The PPM signal is connected to APM 2.5 board’s input CH5 (instead of CH1 for pass through).
Also, a pad needs to be modified on the APM 2.5 board and soldering is required.