Output a constant PWM to 8-channels

Hello, I am a beginner at PX4 programming and have a very simple question. What is the most basic code necessary in C++ to output a constant PWM signal (1500us) to 8-channels simultaneously? Thanks.

for fmu-v2 type this console command: pwm test -a -p 1500
That should output a 1500 usec pulse width on all 8 main pwm channels.
To see the code that does it, look at pwm.c in src/systemcmds/pwm