It still unclear to me (and probably to several other people), but it seems that nowadays when I build the code to Snapdragon Flight from source with make eagle_default, PX4 automatically sets the J13 port to send PWM outputs (GPIOs from 27 to 30), is it right?
According to the DevGuide (Building the Code 路 PX4 Developer Guide):
NOTE: If you use the Qualcomm ESC board (UART-based), then please follow their instructions here. If you use normal PWM-based ESCs boards, then you may continue to follow the instructions on this page.
This question came from the recent discussion on PX4 Github page (Snapdragon Flight ESC support 路 Issue #6962 路 PX4/PX4-Autopilot 路 GitHub). Even though the documentation has been updated, it just says that
For controlling the motors, PWM ESCs can be used. Use connector J13 (next to power module connector) and the following wiring.