# node-gpsd

Interface to [gpsd](http://www.catb.org/gpsd/).

## Installation

With package manager [npm](http://npmjs.org/):

	npm install node-gpsd

## Code instructions

Require `node-gpsd` by calling:

```javascript
    var gpsd = require('node-gpsd');
```

`node-gpsd` has 2 classes: `Daemon` and `Listener`.

The `Daemon` is a wrapper to start and stop `gpsd` from your program. The `Listener` interfaces with a running `gpsd` (not necessarily instantiated via the `Daemon` class).

#### Deamon

A `Daemon` is instantiated by calling:

```javascript
var daemon = new gpsd.Daemon({
    program: 'gpsd',
    device: '/dev/ttyUSB0',
    port: 2947,
    pid: '/tmp/gpsd.pid',
    readOnly: false,
    logger: {
        info: function() {},
        warn: console.warn,
        error: console.error
    }
});
```

The options that are listed above are the default values so calling `new gpsd.Daemon()` will have the same effect. Change the options according your own setup.

The `Daemon` can be started and stopped by calling the appropriate methods:

```javascript
daemon.start(function() {
    console.log('Started');
});
```

or:

```javascript
daemon.stop(function() {
    console.log('Stopped');
});
```

The `Daemon` can log to the console if needed. Logging can be controlled by passing a `logger` property in the options when creating the `Daemon` or by setting the logger field:

```javascript
daemon.logger = new (winston.Logger) ({ exitOnError: false });
```

The logger should have `info`, `warn` and `error` functions that all accept a single parameter.

The `Daemon` is an [EventEmitter](http://nodejs.org/api/events.html#events_class_events_eventemitter) and will emit the following events:

* `died`: when the `Daemon` is killed.

#### Listener

A `Listener` is instantiated by calling:

```javascript
var listener = new gpsd.Listener({
    port: 2947,
    hostname: 'localhost',
    logger:  {
        info: function() {},
        warn: console.warn,
        error: console.error
    },
    parse: true
});
```

The options that are listed above are the default values so calling `new gpsd.Listener()` will have the same effect. Change the options according your own setup.

The `Listener` can be connected to the `gpsd` by calling:

```javascript
listener.connect(function() {
    console.log('Connected');
});
```

and disconnected by calling:

```javascript
listener.disconnect(function() {
    console.log('Disconnected');
});
```

The connection state can be queries by calling:

```javascript
listener.isConnected();
```

To control watching gps events call the methods:

```javascript
listener.watch(options);
listener.unwatch();
```

This will put the `Listener` in and out-of watching mode. The `Listener` is an [EventEmitter](http://nodejs.org/api/events.html#events_class_events_eventemitter) and will emit the following events:

* `gpsd` events like described in the [gpsd documentation](http://www.catb.org/gpsd/gpsd_json.html). All `gpsd` events like: `TPV`, `SKY`, `INFO` and `DEVICE` can be emitted. To receive all `TPV` events just add `listener.on('TPV', function(tpvData))` to your code. When the `parse` option is set to false these events will not be emitted.
* `raw` events contain the raw, unparsed input received from gpsd. Only emitted if `parse` option is set to false.
* `error` when data in a bad format is received from `gpsd`.
* `disconnected` when the connection with `gpsd` is lost.
* `connected` when the connection with `gpsd` is established.
* `error.connection` when the connection is refused.
* `error.socket` on other connection errors.

You can pass options to be sent on to gpsd when issuing the watch command, the default being `{ class: 'WATCH', json: true, nmea: false }`.

If you want to receive raw nmea data from gpsd you should create the listener with `new gpsd.Listener({emitraw: true, parsejson: false})` and issue `listener.watch({class: 'WATCH', nmea: true})`.

It is possible to query the gps device by calling:

```javascript
listener.version(); /* a INFO event will be emitted */
listener.devices(); /* a DEVICES event will be emitted */
listener.device(); /* a DEVICE event will be emitted */
```

The `Listener` can log to the console if needed. Logging can be controlled by passing a `logger` property in the options when creating the `Listener` or by setting the logger field:

```javascript
listener.logger = new (winston.Logger) ({ exitOnError: false });;
```

## Shout outs

Shout outs go to [Pascal Deschenes](http://github.com/pdeschen) for creating the [Bancroft](http://github.com/pdeschen/bancroft) project that formed the basis for `node-gpsd`.