mholtman/xgps

GPS for Elixir

XGPS

GPS for Elixir

XGPS runs as an application and will start along with you application, and connect to an serial port to get GPS data.

Installation

If available in Hex, the package can be installed as:

1. Add xgps to your list of dependencies in mix.exs:

```elixir
def deps do
  [{:xgps, "~> 0.4.0"}]
end
```

2. Ensure xgps is started before your application:

```elixir
def application do
  [applications: [:xgps]]
end
```

3. To make an effort to be platform independent, XGPS uses nerves_uart for the dirty details. Please make sure to follow the instructions for nerves_uart to make this compile and run on your system.

Usage: start

Manually

Simply call:

XGPS.Ports.start_port("name-of-port")

Config

Add a line like this in you config:

config :xgps, port_to_start: {"name-of-port"}

Config with init

If you are using the Adafruit Ultimate GPS you can add:

config :xgps, port_to_start: {"name-of-port", :init_adafruit_gps}

This will send a series of commands to your GPS to configure it. The following commands are then sent:

• "$PMTK313,1*2E" => enable SBAS
• "$PMTK319,1*24" => Set SBAS to not test mode
• "$PMTK301,2*2E" => Enable SBAS to be used for DGPS
• "$PMTK286,1*23" => Enable AIC (anti-inteference)
• "$PMTK314,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0*28" => Output only RMC & GGA
• "$PMTK397,0*23" => Disable nav-speed threshold

These sentences will work to initialize other GPS-types supporting the PMTK command types.

Usage: Get position

Manually

This usage pattern is mostly for testing. Call:

XGPS.Ports.get_one_position

to get the latest fixed positions.

Pay attention to the has_fix if it is true or false. If has_fix=false, you cannot trust the other values.

Automatically (GenStage)

The most common usage pattern is to subscribe to the GenStage producer running. Check out the code inside the example-folder for an implementation for a subscriber. You need to implement (or copy) similar code to your side to receive new positions.

Usage: simulation

Starting manually

Start a simulated port by calling the following:

XGPS.Ports.start_port(:simulate)

Auto-start from config

By adding a line to config:

config :xgps, port_to_start: {:simulate,}

Sending simulated position

Send a simulated position using one of the following commands:

XGPS.Ports.send_simulated_no_fix()
XGPS.Ports.send_simulated_position(1.1,2.2,3.3) # lat, lon, alt

Future development

• Update to current version for all dependencies
• Simulation reading from file

Note

This application was tested on a Raspberry Pi using the AdaFruit Ultimate GPS (1, 2), which essentially uses the chip MTK3339. Guarantees for other systems and chips cannot be given. But please provide feedback if working or not on other systems/chips.