# XGPS
[](https://travis-ci.org/rveshovda/xgps)
[](https://hex.pm/packages/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](https://hex.pm/docs/publish), the package can be installed as:
1. Add `xgps` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[{:xgps, "~> 0.1.0"}]
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](https://github.com/nerves-project/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:
```elixir
XGPS.Ports_supervisor.start_port("name-of-port")
```
### Config
Add a line like this in you config:
```elixir
config :xgps, port_to_start: {"name-of-port"}
```
### Config with init
If you are using the Adafruit Ultimate GPS you can add:
```elixir
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:
```elixir
XGPS.Ports_supervisor.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 (GenEvent)
The most common usage pattern is to subscribe to the GenEvent publisher 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.
## TODO
- Consider GenStage
## Note
This application was tested on a Raspberry Pi using the AdaFruit Ultimate GPS ([1](https://www.adafruit.com/products/746), [2](https://www.adafruit.com/products/2324)), 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.
