Add aref to the rest of the analog controllers

rwaldron · Aug 26, 2015 · f5a7bde · f5a7bde
1 parent 8e616a0
commit f5a7bde
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Showing 2 changed files with 186 additions and 190 deletions.
diff --git a/lib/temperature.js b/lib/temperature.js
@@ -2,6 +2,7 @@ var Board = require("../lib/board.js"),
   Emitter = require("events").EventEmitter,
   util = require("util");
 
+var CELSIUS_TO_KELVIN = 273.15;
 
 function analogHandler(opts, dataHandler) {
   var pin = opts.pin;
@@ -156,27 +157,36 @@ var Controllers = {
       value: analogHandler
     }
   },
-  //http://www.ti.com/lit/ds/symlink/lm35.pdf
   LM35: {
     initialize: {
       value: analogHandler
     },
     toCelsius: {
       value: function(raw) {
-        return (5.0 * raw * 100.0) / 1024.0;
+        // http://www.ti.com/lit/ds/symlink/lm35.pdf
+        // VOUT = 1500 mV at 150°C
+        // VOUT = 250 mV at 25°C
+        // VOUT = –550 mV at –55°C
+
+        var mV = this.aref * 1000 * raw / 1024;
+
+        // 10mV = 1°C
+        return mV / 10;
       }
     }
   },
-  //http://www.ti.com/lit/ds/symlink/lm335.pdf
   LM335: {
     initialize: {
       value: analogHandler
     },
     toCelsius: {
       value: function(raw) {
-        var mv = (raw / 1024.0) * 5000;
-        var k = (mv / 10);
-        return (k - 273.15);
+        // http://www.ti.com/lit/ds/symlink/lm335.pdf
+        // OUTPUT 10mV/°K
+
+        var mV = this.aref * 1000 * raw / 1024;
+
+        return (mV / 10) - CELSIUS_TO_KELVIN;
       }
     }
   },
@@ -189,10 +199,10 @@ var Controllers = {
     toCelsius: {
       value: function(raw) {
         // Analog Reference Voltage
-        var volts = raw * this.aref / 1024;
+        var mV = this.aref * 1000 * raw / 1024;
 
         // tempC = (mV / 10) - 50
-        return (volts * 100) - 50;
+        return (mV / 10) - 50;
       }
     }
   },
@@ -291,8 +301,8 @@ var Controllers = {
         var adcres = 1023;
         // Beta parameter
         var beta = 3975;
-        // 0°C = 273.15 K
-        var kelvin = 273.15;
+        // 0°C = CELSIUS_TO_KELVIN K
+        var kelvin = CELSIUS_TO_KELVIN;
         // 10 kOhm (sensor resistance)
         var rb = 10000;
         // Ginf = 1/Rinf
@@ -315,7 +325,7 @@ var Controllers = {
       value: function(raw) {
         var adcres = 1023;
         var beta = 3950;
-        var kelvin = 273.15;
+        var kelvin = CELSIUS_TO_KELVIN;
         var rb = 10000; // 10 kOhm
         var ginf = 120.6685; // Ginf = 1/Rinf
 
@@ -412,7 +422,7 @@ function Temperature(opts) {
     },
     kelvin: {
       get: function() {
-        return this.celsius + 273.15;
+        return this.celsius + CELSIUS_TO_KELVIN;
       }
     }
   };