upm/examples/javascript/mcp2515-txrx.js

/*
 * Author: Jon Trulson <jtrulson@ics.com>
 * Copyright (c) 2016 Intel Corporation.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

var sensorObj = require('jsupm_mcp2515');

// Instantiate a MCP2515 on SPI bus 0 using a hw CS pin (-1).
var sensor = new sensorObj.MCP2515(0, -1);

// NOTE: This example assumes that only two devices are connected
// to the CAN bus, and that both devices are running this example;
// one in TX (transmit) mode, and one in RX (receive) mode.

// If this is not the case, then in rx mode you may see other
// packets from other devices, or not, depending on whether the
// speed is correct for the network.  In tx mode, errors may be
// generated on the bus, especially if the CAN bus speed does not
// match the rest of the network.

// You should start the receiver example first.  The transmitter
// example will fail after about 5 seconds (timeout) of not being
// able to transmit a message.

function transmit(sensor)
{
    // lets build up a packet and try loading it (8 bytes max).
    var myPayload = "01234567";
    console.log("Loading a packet of 8 numbers (0-7) into a TX buffer...");
    sensor.loadTXBuffer(sensorObj.MCP2515_TX_BUFFER0,
                        0, false, false, myPayload);

    // now lets try to transmit it
    console.log("Transmitting packet...");
    sensor.transmitBuffer(sensorObj.MCP2515_TX_BUFFER0, true);

    console.log("Transmit successful");
    console.log();
}

function receive(sensor)
{
    // There should now be a packet waiting for us in RXB0
    if (sensor.rxStatusMsgs() == sensorObj.MCP2515_RXMSG_RXB0)
    {
        console.log("Packet received in RXB0, decoding...");

        // now lets retrieve and print it
        sensor.getRXMsg(sensorObj.MCP2515_RX_BUFFER0);

        sensor.printMsg();
        console.log();
    }
}

// by default we just receive packets
if (process.argv.length > 2)
{
    // transmit mode
    interval = setInterval(function() { transmit(sensor); }, 500);
}
else
{
    // receive mode
    interval = setInterval(function() { receive(sensor); }, 100);
}

process.on('SIGINT', function()
{
    sensor = null;
    sensorObj.cleanUp();
    sensorObj = null;
    console.log("Exiting...");
    process.exit(0);
});