node-red/nodes/hardware/36-rpi-gpio.js

/**
 * Copyright 2013 IBM Corp.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 **/

var RED = require("../../red/red");
var util = require("util");
var exec = require('child_process').exec;
var fs =  require('fs');

if (!fs.existsSync("/usr/local/bin/gpio")) {
	exec("cat /proc/cpuinfo | grep BCM27",function(err,stdout,stderr) {
		if (stdout.indexOf('BCM27') > -1) {
			util.log('[36-rpi-gpio.js] Error: Cannot find Wiring-Pi "gpio" command');
		}
		// else not on a Pi so don't worry anyone with needless messages.
	});
	return;
}

// Map physical P1 pins to Gordon's Wiring-Pi Pins (as they should be V1/V2 tolerant)
var pintable = {
// Physical : WiringPi
		 "7":"7",
		"11":"0",
		"12":"1",
		"13":"2",
		"15":"3",
		"16":"4",
		"18":"5",
		"22":"6"
}
var tablepin = {
// WiringPi : Physical
		"7":"7",
		"0":"11",
		"1":"12",
		"2":"13",
		"3":"15",
		"4":"16",
		"5":"18",
		"6":"22"
}

function GPIOInNode(n) {
	RED.nodes.createNode(this,n);
	this.buttonState = -1;
	this.pin = pintable[n.pin];
	this.intype = n.intype;
	var node = this;

	if (this.pin) {
		exec("gpio mode "+node.pin+" "+node.intype, function(err,stdout,stderr) {
			if (err) node.error(err);
			else {
				node._interval = setInterval( function() {
					exec("gpio read "+node.pin, function(err,stdout,stderr) {
						if (err) node.error(err);
						else {
							if (node.buttonState !== Number(stdout)) {
								var previousState = node.buttonState;
								node.buttonState = Number(stdout);
								if (previousState !== -1) {
									var msg = {topic:"pi/"+tablepin[node.pin], payload:node.buttonState};
									node.send(msg);
								}
							}
						}
					});
				}, 250);
			}
		});
	}
	else {
		this.error("Invalid GPIO pin: "+this.pin);
	}
}

function GPIOOutNode(n) {
	RED.nodes.createNode(this,n);
	this.pin = pintable[n.pin];
	var node = this;

	if (this.pin) {
		process.nextTick(function() {
			exec("gpio mode "+node.pin+" out", function(err,stdout,stderr) {
				if (err) node.error(err);
				else {
					node.on("input", function(msg) {
						if (msg.payload === "true") msg.payload = true;
						if (msg.payload === "false") msg.payload = false;
						var out = Number(msg.payload);
						if ((out == 0)|(out == 1)) {
							exec("gpio write "+node.pin+" "+out, function(err,stdout,stderr) {
								if (err) node.error(err);
							});
						}
						else node.warn("Invalid input - not 0 or 1");
					});
				}
			});
		});
	}
	else {
		this.error("Invalid GPIO pin: "+this.pin);
	}
}

exec("gpio reset",function(err,stdout,stderr) {
	if (err) {
		util.log('[36-rpi-gpio.js] Error: "gpio reset" command failed for some reason.');
	}
	exec("gpio load spi",function(err,stdout,stderr) {
		if (err) {
			util.log('[36-rpi-gpio.js] Error: "gpio load spi" command failed for some reason.');
		}

		RED.nodes.registerType("rpi-gpio in",GPIOInNode);
		RED.nodes.registerType("rpi-gpio out",GPIOOutNode);

		GPIOInNode.prototype.close = function() {
			clearInterval(this._interval);
		}

		GPIOOutNode.prototype.close = function() {
			exec("gpio mode "+this.pin+" in");
		}

	});
});