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Custom flight mode using SRV_Channels::set_output_pwm_chan() not working

I created a new flight mode and am trying to directly send a PWM command to the throttle and aileron channels using the lines:

SRV_Channels::set_output_pwm_chan(SRV_Channel::k_aileron, 1900)
SRV_Channels::set_output_pwm_chan(SRV_Channel::k_throttle, 1300)

but it doesn’t seem to be doing anything.

I am testing this on the ground, and I know that the code is entering the ::update() function of the new flight mode because I’ve added a hal.console->printf("updating") for debugging purposes and am watching the serial monitor.

FWIW, I have all arming checks disabled, and also one thing I can’t figure out is that when I’m in this new mode, I can’t seem to move the throttle to spin up the motors but my control surfaces can move (throttle not working with both plane.throttle_allows_nudging = false and = true).

Here’s how my flight mode code looks like:

#include "Plane.h"
#include "mode.h"

ModeTest::ModeTest() {
	// Do nothing

bool ModeTest::_enter() {
    plane.throttle_allows_nudging = false;

    return true;

void ModeTest::update() {

	SRV_Channels::set_output_pwm_chan(SRV_Channel::k_aileron, 1900);  
	SRV_Channels::set_output_pwm_chan(SRV_Channel::k_throttle, 1300); 

void ModeTest::_exit() {
	// Do nothing

Try using set output scaled, discord is a good place for code advice,

Hey Peter, that sort of worked!

I am able to spin up the motors now using set_output_scaled(SRV_Channel::k_throttle, 10); (for 10% throttle). But I still can’t seem to move the control surfaces.

From adding some hal.console->printf() statements in manual mode, it looks like the scaled output ranges for the k_aileron, k_elevator, and k_rudder range from -4500, 4500. I then tried these lines:

SRV_Channels::set_output_scaled(SRV_Channel::k_aileron, 4500); 
SRV_Channels::set_output_scaled(SRV_Channel::k_rudder, -4500); 
SRV_Channels::set_output_scaled(SRV_Channel::k_elevator, 4000);

But it doesn’t seem to move the servos at all (also tried ranges from [-1, 1] (normalized ranges), [1000, 2000] (pwm ranges), and [0, 100] (percentage ranges)).

I also still can’t figure out why in my new flight mode I am able to manually move the servos but not the throttle. FWIW, it also looks like when I manually move the aileron, the rudder servo also moves, which I believe implies that it’s performing a coordinated turn. I’m not exactly sure how I enabled coordinated turns for this flight mode.

And thank you for the Discord suggestion, will do that for future code questions.

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