This project started off as a fork of Choral's OrionMQTT demo app. It is a Java MIDlet application which includes the Paho library to send MQTT position messages in OwnTracks format with Choral Greenwich hardware.

The Choral Greenwich is a Java based GPS- and GPRS-enabled sensing box for vehicles which, together with this application, enables it to routinely report a vehicle's position using the OwnTracks JSON format over MQTT. An example payload may look like this:

{
    "_type": "location",
    "alt": 160,
    "batt": 12.2,
    "cog": 130,
    "dist": 18903,
    "lat": "xx.xxxxxx",
    "lon": "y.yyyyyy",
    "vel": 82,
    "t": "t",
    "tst": "1406803894"
}

• Message payloads compatible with OwnTracks' JSON which means you can use the OwnTracks apps to display location data.
• Location updates on a per/time and per/moved distance basis. For example, publish location after vehicle has moved 200 meters or at most 120 seconds, whichever comes first.
• MQTT authentication
• TLS
• Subscription to a configurable topic branch for remote-control / information retrieval.
• Watchdog: device resets itself if GPS or GPRS unavailable or in case of the device hanging itself up.
• Configurable via SMS.
• Over the Air upgrades (OTA)
• MQTT Last Will and Testament (LWT) messages for monitoring
• The OwnTracks Live Map has support for the additional JSON elements provided by Greenwich.
• Configurable MQTT client-ID which defaults to the device's IMEI.
• GPIO states published over MQTT.
• Power-up handling:
  • when ignition is switched on
  • when movement with the builtin accelerometer is detected
  • alarm clock
• Power-down handling
  • when ignition is switched off
  • movement sensor detects the device is stationary
  • alarm clock

The app requires a Greenwich device as well as an MQTT broker such as Mosquitto or HiveMQ. Installing the app onto an existing Greenwich requires a serial connection.

The application is highly configurable. Note, that if you have been using a Greenwich, the format of the commands, as well as most of the configurable settings have changed.

• http://mosquitto.org/
• http://www.choral.it/greenwich
• http://owntracks.org