Qualcomm Flight RB5 External Flight Controller

Repurpose J12 as a UART

There is a bug in the `1.0.5-M0052-9.1-perf` release preventing this from working. We are investigating a fix

Summary

Normally, PX4 uses the J12 connector’s UART (3.3V TTL) for an RC input. But, if you want to use an external flight controller you can instead use this UART as a means to communicate using something like MAVLink.

Disable PX4 from Running on DSP

First, you need to disable PX4 from running on target.

systemctl disable rb5-px4-start

Reboot the system.

Create a Cable

This is the J12 pinout.

Interface with In Linux

There is a bug in the `1.0.5-M0052-9.1-perf` release preventing this from working. We are investigating a fix

This UART shows up as /dev/ttyHS1. Here’s a simple Python example.

import serial

uart_dev='/dev/ttyHS1'

uart = serial.Serial(uart_dev, 115200, xonxoff=False, rtscts=False, dsrdtr=False)
while True:
	bytes = uart.read_all()
	if len(bytes) > 0:
		print(bytes)

Repurpose J19 as a UART

There is a bug in the `1.0.5-M0052-9.1-perf` release preventing this from working. We are investigating a fix

Summary

Similar to above, on RB5 Flight, J19 has a UART that is typically used for GNSS/PX4. This can be used similar as above using /dev/ttyHS2.