Can some one tell me if you can use pass though to update firmware,calibrate and change directions of motors with the holybro pixhawk4. If this can be done can you explain how to.
This forum is about PX4, this is not possible with PX4 running on your pixhawk4 unless you want to write the code yourself.
Also D-shot and Blheli-telemetry are not supported yet. They do work great with oneshot or regular rc-pwm and PX4.
But you can do passtrough, D-shot and Blheli-telemetry using Ardupilot on your Pixhawk4: http://ardupilot.org/copter/docs/common-dshot.html
They have this forum.