node-red-mcp23xxx/lib/mcp23017-node.js

Library to use the MCP23008 and MCP23017 I/O Expanders with the Raspberry Pi

/**
 * Copyright 2015 Sorin Chitu.
 *
 * 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.
 **/

module.exports = function(RED) {
    var MCP = require("./mcp23017.js");
    String.prototype.endsWith = function(suffix) {
        return this.match(suffix + "$") == suffix;
    };

    function mcp23017_Node(config) {
        RED.nodes.createNode(this, config);

        this.topic = config.topic;
        if (this.topic.endsWith("/") == false)
            this.topic += '/';

        var node = this;

        var icAddress = parseInt(config.address);
        var icBus = parseInt(config.bus);
		
        var mcp = new MCP({
            address: icAddress, //all address pins pulled low
            bus: icBus, // Model B
            reverse: config.reverse,
            debug: false
        });

        //set all GPIOS to be OUTPUTS
        for (var i = 0; i < 16; i++) {
            mcp.pinMode(i, mcp.OUTPUT);
            mcp.digitalWrite(i, mcp.HIGH);
        }

        this.on('input', function(msg) {
            this.status({
                fill: "red",
                shape: "dot",
                text: "Busy`"
            });
            if (msg.topic.toUpperCase().indexOf('ALL') > -1) {
                mcp23017_set_all_outputs(msg.payload);
                send_status_message("ALL", node.topic + pin, msg.payload);
            } else if (msg.topic.toUpperCase().indexOf('STATUS') > -1) {
                mcp23017_send_status();
            } else {
                var pin = get_pin_from_topic(msg.topic);
                if (pin >= 0 && pin < 16) {
                    mcp23017_process(pin, msg.payload);
                    send_status_message(pin, node.topic + pin, msg.payload);
                } else {
                    node.warn("Topic should contain a valid pin in the rannge 0..15: [" + msg.topic + "]");
                }
            }
            this.status({
                fill: "green",
                shape: "dot",
                text: "Ready"
            });
        });

        function send_status_message(pin, topic, state) {
            var statusMsg = {}
            statusMsg.topic = topic + pin;
            statusMsg.payload = "Sent " + state + " to relay " + pin;
            node.send(statusMsg);
        }

        function mcp23017_send_status() {
            for (var pin = 0; pin < 16; pin++) {
                mcp.digitalRead(pin, function(err, value) {
                    node.log("Pin " + pin + " - " + value);
                    var statusMsg = {};
                    statusMsg.topic = node.topic + pin;
                    statusMsg.payload = {
                        pin: pin,
                        value: (value) ? "OFF" : "ON"
                    };
                    node.send(statusMsg);
                });
            }
        }

        function mcp23017_set_all_outputs(state) {
            for (var pin = 0; pin < 16; pin++) {
                mcp23017_process(pin, state);
            }
        }

        function mcp23017_process(pin, state) {
            mcp.digitalWrite(pin, (state == "ON") ? mcp.LOW : mcp.HIGH);
        }

        function get_pin_from_topic(topic) {
            var parts = topic.split('/');
            var index = parts.length - 1;
            return parseInt(parts[index]);
        }
    }

    RED.nodes.registerType("mcp23017", mcp23017_Node);
}