Module for finding and reading OneWire temperature sensors, specifically beginning with ID "28" (like the DS18B20)

temp.js

var fs = require('fs');
var path = require('path');

var devicesRoot = '/sys/bus/w1/devices/';
var slavesFilename = path.resolve(devicesRoot, 'w1_bus_master1/w1_master_slaves');

exports.find = function find (fn) {
  fs.readFile(slavesFilename, 'ascii', function (err, data) {
    if (err) return fn(err);
    var slaves = data.trim().split('\n');
    var therms = slaves.filter(function (id) {
      return /^28-/.test(id);
    });
    fn(null, therms);
  });
};

exports.read = function read (id, fn) {
  var filename = path.resolve(devicesRoot, id, 'w1_slave');
  fs.readFile(filename, 'ascii', function (err, data) {
    if (err) return fn(err);
    if (/\bYES\b/.test(data)) {
      var value = parseInt(/t=(\d+)/.exec(data)[1], 10);
      var c = value / 1000;
      fn(null, c);
    } else {
      // TODO: handle bad reading
    }
  });
};

usage.js

var temp = require('./temp');

temp.find(function (err, therms) {
  therms.forEach(function (id) {
    temp.read(id, function (err, c) {
      var f = (c * (9/5)) + 32;
      console.log(id, c, f);
    });
  });
});