Diff: potSensor.h

Revision:

17:ab3cec0c8bf4

Child:

23:14f8c5004cd0

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/potSensor.h	Fri Feb 27 04:14:04 2015 +0000
@@ -0,0 +1,49 @@
+// Potentiometer plunger sensor
+//
+// This file implements our generic plunger sensor interface for a
+// potentiometer.
+
+#include "FastAnalogIn.h"
+
+// The potentiometer doesn't have pixels, but we still need an
+// integer range for normalizing our digitized voltage level values.
+// The number here is fairly arbitrary; the higher it is, the finer
+// the digitized steps.  A 40" 1080p HDTV has about 55 pixels per inch
+// on its physical display, so if the on-screen plunger is displayed
+// at roughly the true physical size, it's about 3" on screen or about
+// 165 pixels.  So the minimum quantization size here should be about
+// the same.  For the pot sensor, this is just a scaling factor, 
+// so higher values don't cost us anything (unlike the CCD, where the
+// read time is proportional to the number of pixels we sample).
+const int npix = 4096;
+
+class PlungerSensor
+{
+public:
+    PlungerSensor() : pot(POT_PIN)
+    {
+        pot.enable();
+    }
+    
+    void init() 
+    {
+    }
+    
+    int lowResScan()
+    {
+        return int(pot.read() * npix);
+    }
+        
+    bool highResScan(int &pos)
+    {
+        pos = int(pot.read() * npix);
+        return true;
+    }
+    
+    void sendExposureReport(USBJoystick &) 
+    { 
+    }
+    
+private:
+    FastAnalogIn pot;
+};