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Jane Cleland-Huang Drone Class 02/18

Controling a Pixhwak with a Pi3

Steps:

  1. Add 5V usb supply
  2. Attach dupont connectors to serial cable
  3. Test powering up and loging in to the Pi
  4. Configure the Pixhawk Serial Port
  5. Connect Pi to Pixhawk

Step1: Add 5V usb supply

Use the crimp tool to attach the JST connector to open UBEC input leads making sure to have the correct orientation for the 12V supply coming out ofthe base of the Iris (red to red and black to black)

Image of JST Connector Image of UBEC

Step2: Add Dupont connector to serial cable

Again strip and crimp the connector to the open end of the cable taking care to get the pin order correct

Image of Pi3 Pinout Pixhawk Serial Pinout

Reference:

Note: Tx on pixhawk goes to Rx on Pi

Step3: Power up and connect to the Pi

i] Insert microSDCard into Pi3 (noting the number on it/the box)

ii] Connect UBEC to JST connector underneath Iris and the microUSB end to the Pi3

iii] Connect the Iris battery to power up the Pi

iv] Connect your computer to the local WLAN: * SSID: NDSUAS * PSWD: NotreDame

v] ssh in

ssh pi@Pi<number>.local

* User: Pi
* PSWD: NotreDame

vi] Shutdown the Pi

    $ sudo shutdown -h now

Step4: Configure the Pixhawk Serial Port

i] Install QGroundcontrol on a local machine

ii] Connect a USB cable between the microusb port on the side of the Iris to a local machine

iii] QGC should connect to the Iris automatically

iv] Click on the gears symbol and go to the bottom where the parameters option is QGC screenshot

v] Under parameters, search for:

vi] Unplug the Iris

Step5: Connect Pi to Pixhawk

i] Unscrew the top of the Iris

ii] Insert DF13 connect (serial cable) into “Serial 4/5” port

iii] Connect Dupont connect to Pi3 Serial port header

iv] ssh into pi and run:

    $ mavproxy.py --master=/dev/ttyS0 --baudrate 57600 --aircraft MyCopter

If it fails to connect go back and check all connections and the setting changes you made

v] Once successfully connected you should see:

    >> MAV  //Tab to see command options

vi] Connect to QGC again via the external USB cable and monitor settings as you change them via the ssh and the Pi.

Eg: Change flight modes as follows. This will change to auto flight mode if not already in it (See documentation here on available flightmodes. Not all flightmodes are available on all platforms.)

        >> MAV mode auto

Play around with options. See Mavproxy docs here

v] Close Mavproxy and now try interacting with the Pixhawk via a python script. Start with the test connection script available in ~/Desktop/

Close the mavproxy session 1st.

    $ python -i testconnection.py

Once connected close the session, you will come back to scripting just now.

Step6: Flight logs:

The pixhawk creats 2 types of log files, dataflash (.bin) and telemetry logs (.tlogs). Both are in a binary format requiring an ingestor to interperate them. (see the docs for more details)

When you ran mavproxy.py a t.log file was created

Check for the log at: MyCopter/logs//flight1/flight.tlog

You can either examine this log file in a number of ways:

Mission Planner on Windows

MissionPlanner is another ground control software tool that has good tools for review and exporting the logs to ASCII formats. Instructions for exploring a log file can be found here. You can either download the flight log from the Iris manually or if you plug the usb cable directly back into the Iris you can download it via Mission planner. (A 3rd option is to connect to the Iris using the telemetry radio but generally log files are too large for this to be efficient).

Alternative to Mission Planner and better for report writing: MAVExplorer.py

If you do not wish to run Mission Planner in Windows, or wish to create plots for reports/later reference etc MAVExplorer is very useful.

If you wish to install MAVExplorer on your own local machine, follow the instructions here. Or, MAVExplorer, it is already installed on the Pi, you will just need to forward X over shh as it’s a GUI application.

Whichever avenue you take, once installed:

$ MAVExplorer.py <*.tlog/*.bin>

Tab to see available commands eg:

MAV> map

MAV> graph MODE.Mode ATT.DesPitch POS.Alt

7. Exercise

8. Extension exercise (optional)