Using External Mode over FTDI with Pixhawk 1

In UAV Toolbox Support Package for PX4^® Autopilots, serial communication is supported over the native-USB port and non-usb ports (for example, /dev/ttyS6) on the Pixhawk Series boards. To achieve serial communication over non-USB serial port, a serial-to-USB FTDI converter is required.

The below image shows the connection between Serial 4 (/dev/ttyS6) on Pixhawk 1 board and the USB port on host computer, by using an FTDI converter.

The below table lists the serial pins on the Pixhawk 1 board and their FTDI mapping. The pins listed here are from left to right.

Pin and FTDI Mapping for Pixhawk 1

Serial port on Pixhawk 1		FTDI
1	+5V	Not connected
2	Serial 4 Tx	FTDI Rx
3	Serial 4 Rx	FTDI Tx
4	Serial 5 Tx	Not connected
5	Serial 5 Rx	Not connected
6	GND	FTDI GND

Once the above hardware connections are completed, open the Configuration Parameters dialog box in Simulink, and set the serial port to dev/ttyS6 (go to Hardware Implementation pane > Target Hardware Resources > External Mode, and enter dev/ttyS6 in the Hardware board serial Port field). Now you can run the model in External mode over FTDI with Pixhawk 1 board. A sample screen is shown below.