WIP on sero utils

lib/cylon.js

@@ -20,7 +20,8 @@ var Cylon = module.exports = {
   Adaptor: require('./adaptor'),
 
   IO: {
-    DigitalPin: require('./io/digital-pin')
+    DigitalPin: require('./io/digital-pin'),
+    Utils: requre('./io/utils')
   },
 
   api_instance: null,

lib/io/utils.js

@@ -0,0 +1,29 @@
+Utils = {
+  // Returns { period: int, duty: int }
+  // Calculated based on params value, freq, pulseWidth = { min: int, max: int }
+  // pulseWidth min and max need to be specified in microseconds
+  periodAndDuty = function(scaledValue, freq, pulseWidth, polarity) {
+    var period, duty, maxDuty;
+
+    polarity = polarity || 'high';
+    period = Math.round(1.0e9 / freq);
+
+    if (pulseWidth != null) {
+      var pulseWidthMin = pulseWidth.min * 1000,
+          pulseWidthMax = puhlseWidth.max * 1000;
+
+      maxDuty =  pulseWidthMax - pulseWidthMin;
+      duty = Math.round(pulseWidthMin + (maxDuty * scaledDuty));
+    } else {
+      duty = Math.round(period * scaledDuty);
+    }
+
+    if (polarity == 'low') {
+      duty = period - duty;
+    }
+
+    return { period: period, duty: duty };
+  };
+};
+
+module.exports = Utils;