Here at Gunner Technology we needed a GPS tracker that could HTTP POST NMEA sentences to our server and let us use the GPS data in our web applications.
We decided to do this using the Onion Omega, particularly because we could use Javascript on the hardware component too so that we have one language across all our components, from Hardware to Client to Server.
However we ran into an issue during our prototype phase, we originally ordered the Onion GPS expansion and that did not arrive in time so we made due with what we had - an Adafruit Ultimate GPS module - so that we could prototype the project in time. As a result we have two codebases the Adafruit/ which has Python and Arduino code, and the Expansion/ base. Depending on which you prefer to use we have two different instruction sets for setting the project up.
An Instructable for the Hardware setup: [Link] (http://www.instructables.com/id/SureTrac-Open-Source-Software-Integrated-GPS/)
An Example server source: [Link] (https://github.com/gunnertech/SureTrac_Example_Server)
There are two files of interest - the .ino file and the .py file.
If you want to refresh the GPS at 1Hz or slower here is the procedure:
- Flash the Arduino/Arduino Dock with the .ino file
- Move the .py file to /home/root (or just ~ if your logged in as root)
- Create a "suretrac.cfg" file in the same directory as the .py file and modify the rates and URL. Here is an example file:
[SureTrac]
post_url: 'https://YOUR_URL_HERE.TLD/' # Where we'll HTTP POST the NMEA sentence to
post_rate: 1 # The rate at which the Omega will push the NMEA sentence to the server- Install the dependencies
opkg update
opkg install python-light
opkg install pyOnionI2C
opkg install python-codecs- Make the script run at startup by adding the following to your /etc/rc.local file
python /home/root/I2C_Read_And_Post.py &The procedure is similar to above except you need to change the Arduino code to also poll the GPS module faster - this is simple all you have to do is change the code at these two lines
Since the Omega Expansion has a rate-locked GPS, you shouldn't go faster than the GPS poll rate - I do not know what that rate is - but we use 1 Hz and that works great.
The procedure is simpler for the Omega Expansion:
- Copy the gps.js file to /home/root (or just ~ if your logged in as root)
- Create a .env file similar to below in the same directory as the gps.js file
URL=https://YOUR_HIP_URL_HERE.io
RATE=1000 # In ms- Install Dependencies
opkg update
opkg install node
cd ~/
npm install dotenv
npm install needle- Make the script run at startup by adding the following to your /etc/rc.local file
node /home/root/gps.js &