there have output pwm by px4io , no px4fmu in the RCOutput.cpp file of the libraries/AP_HAL_PX4 directory ,because alt_fd value is -1. so without px4io, how does the pixracer output pwm signal?
Directly from the main processor. As the Aux channels do on PIxhawk,
But _alt_fd is -1 all the time ,because there ( https://github.com/ArduPilot/ardupilot/blob/master/libraries/AP_HAL_PX4/RCOutput.cpp#L57 ) is never going to be run. So i think that the primary output is only the IO instead of fmu.
Can the PWM_OUTPUT0_DEVICE_PATH be opened by FMU instead of IO?
The Pixracer does not have an I/O processor.
thanks , i know that output directly from the main processor.I don’t understand how the pixracer output pwm signal by fmu becauce of _alt_fd is -1 all the time.