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node-red-nodes/hardware/mcp3008/pimcp3008.js

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module.exports = function(RED) {
"use strict";
var fs = require('fs');
// unlikely if not on a Pi
try {
var cpuinfo = fs.readFileSync("/proc/cpuinfo").toString();
if (cpuinfo.indexOf(": BCM") === -1) { throw "Info : "+RED._("rpi-gpio.errors.ignorenode"); }
} catch(err) {
throw "Info : "+RED._("rpi-gpio.errors.ignorenode");
}
var mcpadc = require('mcp-spi-adc');
var mcp3008 = [];
function PiMcpNode(n) {
RED.nodes.createNode(this,n);
this.pin = n.pin || 0;
this.interval = n.interval || 1000;
this.dnum = parseInt(n.dnum || 0);
var node = this;
try {
fs.statSync("/dev/spidev0."+node.dnum);
if (mcp3008.length === 0) {
for (var i=0; i<8; i++) {
mcp3008.push(mcpadc.openMcp3008(i, { deviceNumber:node.dnum }, function (err) {
if (err) { node.error("Error: "+err); }
}));
}
}
node.on("input", function(msg) {
var pin = null;
if (node.pin === "M") {
var pay = parseInt(msg.payload.toString());
if ((pay >= 0) && (pay <= 7)) { pin = pay; }
else { node.warn("Payload needs to select channel 0 to 7"); }
}
else { pin = parseInt(node.pin); }
if (pin !== null) {
mcp3008[pin].read(function (err, reading) {
if (err) { node.warn("Read error: "+err); }
else { node.send({payload:reading.rawValue, topic:"adc/"+pin}); }
});
}
});
}
catch(err) {
node.error("Error : Can't find SPI device - is SPI enabled in raspi-config ?");
}
node.on("close", function(done) {
if (mcp3008.length !== 0) {
var j=0;
for (var i=0; i<8; i++) {
mcp3008[i].close(function() { j += 1; if (j === 8) {done()} });
}
mcp3008 = [];
}
else { done(); }
});
}
RED.nodes.registerType("pimcp3008",PiMcpNode);
}