node-digimesh

This is a node module that implements the XBee Digimesh protocol.

Dependencies

• serialport

Description

The goal is to wrap the DigiMesh protocol with a simple callback interface that doesn't require a user to worry about frame_id numbers or binary buffers. The serialport library provides the serial communication.

This library provides a callback API by maintaining an internal callback queue with callbacks for each unacknowledged message. The application provides a callback for each sent message. When the AT command response or message ACK is received, that callback is looked up from the queue and invoked. This makes it possible to use DigiMesh XBees without caring much about the underlying protocol.

There is also an event that is fired for each new message or response. By default, the event does not fire when a callback has been provided.

Note: The XBees must be in API mode (AP=1).

License

This library is under the BSD-2-Clause license.

Installation

npm install digimesh

Testing

Testing is done with mocha, chai, and sinon. Set the environment variables XBEE_DEVICE and XBEE_BAUD, then run npm test or mocha. You must have at least one other XBee on the network to bounce messages off of.

Usage

You'll have to RTFS and play with it to get everything, but here are some examples.

Initialization

var Xbee = require('./digimesh');

var xbee = new Xbee({ device: '/dev/ttyU0', baud: 115200 }, function() {
    console.log('xbee is ready');
    // do stuff
});

The configuration object contains the following options:

• device A serial device node on your machine
• baud The serial baud rate of the device
• always_fire_event Whether to fire message events even when a callback was provided

The device and baud parameters are passed directly to the serialport library.

AT commands

A handful of AT commands are supported, with more being added. Most of them require special handling, so there isn't a general 'send AT command' function.

// ask for node identifier string
xbee.get_ni_string(function(err, data) {
    if (err) return console.err(err);
    console.log("my NI is '" + data.ni + "'");
});

// set node identifier string
xbee.set_ni_string('my_xbee_name', function(err, data) {
    if (err) return console.err(err);

    // print the human-friendly version
    console.log(xbee.AT_COMMAND_RESPONSE_STATUS_STRINGS[data.status]);

    // check based on the constants
    if (data.status === xbee.AT_COMMAND_RESPONSE_STATUS_OK)
        console.log('it worked');
    else {
        // do something
    }
});

Discovering Nodes

// find all nodes on the network
xbee.discover_nodes(function(err, nodes) {
    if (err) return console.err(err);

    console.log('%d nodes found:', nodes.length);
    console.dir(nodes);
});

Message Handling

xbee.on('message_received', function(data) {
    console.log('received a message from %s!', data.addr);
    console.dir(data);

    // don't be rude, say hello!
    xbee.send_message({
        data: new Buffer("hello"),
        addr: data.addr,
        broadcast: false,
    },
    // callback
    function(err, data) {
        if (err) return console.error(err);

        // print the string status message for the status we got back
        console.log('delivery status: %s',
            xbee.DELIVERY_STATUS_STRINGS[data.status]);

        // print the response object
        console.dir(data);
        console.log('goodbye');
    })
});