Perhaps someone have the same problem - I’m running Arducopter 3.5.2 on RBPi3 with Elre-PXFMini.
With that configuration calibration of ESCs is impossible according to official documentation on ardupilot.org pages because when ardupilot service starts, ESCs are not in calibration phase yet.
i think you will need to calibrate them with your tx and rx connected directly to the ESCs.
look for the manual of your ESCs it should be documented how to do it. usually this involves putting throttle to full and powerup the esc, then move throttle to minimum and notice the beeping tones when doing so.
OK, that’s the basic calibration and seems to be only one way to calibrate. Pity, I hoped I can do it at once via flight controller somehow.
yes i think for now its the only way to calibrate escs with linux fc.
you could use a servo splitter cable to do more than one at a time if you have a y-cable or even four servo splitter cable with enough pins.
Yes you can do it using software, https://github.com/erlerobot/ros_erle_pwm or writing a python script using this library https://github.com/adafruit/Adafruit_Python_PCA9685 , but it is tricky and risky…
@Linus solution is easier and much much safer