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VOXL 2 Connecting an External Flight Controller


Summary

Although VOXL 2 has the capability to run PX4 in a real time DSP, some use cases call for an external flight controller.

PX4 can start just like a normal linux systemd service, so it can be disabled just as easy.

Communication

Disable PX4 from Running on DSP

Note: beta shipments currently don’t have PX4 enabled by default.

From Applications Processor

A UART is exposed on a JST connector on the M0090 or PCIe/5G Modem Carrier add-on board at J8 pins 2/3.

This is

Create a Cable

This is the M0090-J9 pinout, using a 6-pin JST connector:

Pin#SignalNotes/Usage
1VREG_3P3V_RC3.3V Switchable Power Output *
2RC_UART_TX (output, not used)APPS_QUP_13, 3.3V signal levels
3RC_UART_RX (input)APPS_QUP_13, 3.3V signal levels
3I2CSDA
5I2CSCL
6GNDGND

Interface with In Linux

This UART shows up as /dev/ttyHS0. Here’s a simple Python example.

import serial

uart_dev='/dev/ttyHS0'

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