A 7135 regulator turns on and off much faster than the PWM frequency. If the light uses 7135, the PWM can be measured at the output.
With a proper linear or switched regulator it is possible to low-pass filter the PWM signal to create a reference voltage for an opamp. But that doesn’t work for 7135 which has everything built in.
Eliminating the noise means to increase the PWM frequency. That’s mostly possible for the 7135 channels. Unfortunately the red channel uses a different regulator that doesn’t like high frequency PWM. Currently Anduril doesn’t support individual PWM frequency per channel, thus all are slow.
It’s not really unsupported as much as just not implemented yet. I’ve been meaning to add a clause to each set_level_*() function for this light, to detect if it’s turning on from zero, and set the PWM registers differently for each channel mode. That would allow it to use faster PWM on white-only modes, and eliminate the audible noise and reduce visible pulsing. Then only the red modes would be slow.
(edit: all 3 channels use a single timer/counter, so their phases and frequencies are locked together by the hardware… so in combined white+red modes, the white part would run slower too, not just the red … but at least the white-only modes could run faster)
I should probably also remove the memory timer from the default config, and turn off extended simple UI. With recent discussions about simple UI being too complicated, I think it’d be good to remove extended simple UI from all default builds. And though I like using a memory timer, it seems people prefer not to have that in the default config.