土壌水分センサーの計測値をIFTTTを使ってSlack通知する

出力値   状態
0~1292  乾いた土
1292~3017   湿った土
3017~4095   水の中

/**
 * Raspberry Pi 2 (Model B) read SPI data from MCP3208 chip, 8 possible adc's.
 */

var raspi    = require('raspi');
var gpio     = require('raspi-gpio');
var request  = require('request');

const HIGH   = gpio.HIGH;
const LOW    = gpio.LOW;
const Input  = gpio.DigitalInput;
const Output = gpio.DigitalOutput;

var initHandler = function() {

    var d_in  = new Output('GPIO10'); //SPI_MOSI
    var d_out = new Input('GPIO9');   //SPI_MISO
    var clk   = new Output('GPIO11'); //SPI_CSLK
    var cs    = new Output({ 'pin' : 'GPIO8', 'pullResistor' : gpio.PULL_UP });  //SPI_CE0

    var clock = function(count) {
        for(var i = 0; i < count; i++) {
            clk.write(HIGH);
            clk.write(LOW);
        }
    };

    var readValue = function() {
        cs.write(LOW); //start

        var i;
        var ch  = 0; // 0 ch. (0~7)
        var cmd = ( ch | 0x18 ) << 3;
        for(i = 0; i < 5; i++) {
            d_in.write( ( cmd & 0x80 ) ? HIGH : LOW );
            cmd <<= 1;
            clock(1);
        }

        var result = 0;
        for(i = 0; i < 13; i++) { // one null bit and 12 ADC bits.
            result <<= 1;
            clock(1);
            if(d_out.read()) { // === 1
                result |= 0x1;
            }
        }

        cs.write(HIGH); //end

        //console.log('result : ', result);
        // IFTTT連携
        var options = {
            uri: "<IFTTTのhook URL>",
            headers: {
                "Content-type": "application/json",
            },
            json: {
                "value1": String(result)
            }
        };
        request.post(options, function(error, response, body) {
            process.exit();
        });
    };

    readValue(); 
};

raspi.init(initHandler);