upm/examples/javascript/mcp2515-txrx.js

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/*
* 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);
});