firmata-electron/examples/k22.js

A library to control an arduino running firmata

/**
 * Sample script to take readings from a k22 co2 sensor.
 * http://www.co2meter.com/collections/co2-sensors/products/k-22-oc-co2-sensor-module
 */
var Board = require("../lib/firmata").Board;
var board = new Board("/dev/tty.usbmodemfa131", function() {
  board.sendI2CConfig();
  board.on("string", function(string) {
    console.log(string);
  });
  setInterval(function() {
    board.sendI2CWriteRequest(0x68, [0x22, 0x00, 0x08, 0x2A]);
    board.sendI2CReadRequest(0x68, 4, function(data) {
      var ppms = 0;
      ppms |= data[1] & 0xFF;
      ppms = ppms << 8;
      ppms |= data[2] & 0xFF;
      var checksum = data[0] + data[1] + data[2];
      if (checksum === data[3]) {
        console.log("Current PPMs: " + ppms);
      } else {
        console.log("Checksum failure");
      }
    });
  }, 2000);
});