Diff: plunger.h

Revision:

44:b5ac89b9cd5d

Parent:

43:7a6364d82a41

Child:

45:c42166b2878c

--- a/plunger.h	Sat Feb 06 20:21:48 2016 +0000
+++ b/plunger.h	Sun Feb 07 03:07:11 2016 +0000
@@ -15,48 +15,23 @@
     PlungerSensor() { }
     virtual ~PlungerSensor() { }
     
-    // Number of "pixels" in the sensor's range.  We use the term "pixels"
-    // here for historical reasons, namely that the first sensor we implemented
-    // was an imaging sensor that physically sensed the plunger position as
-    // a pixel coordinate in the image.  But it's no longer the right word,
-    // since we support sensor types that have nothing to do with imaging.
-    // Even so, the function this serves is still applicable.  Abstractly,
-    // it represents the physical resolution of the sensor in terms of
-    // the number of quanta over the full range of travel of the plunger.
-    // For sensors that inherently quantize the position reading at the 
-    // physical level, such as imaging sensors and quadrature sensors, 
-    // this should be set to the total number of position steps over the 
-    // range of travel.  For devices with physically analog outputs, such 
-    // as potentiometers or LVDTs, the reading still has to be digitized 
-    // for us to be able to work with it, which means it has to be turned
-    // into a value that's fundamentally an integer.  But this happens in
-    // the ADC, so the quantization scale is hidden in the mbed libraries.
-    // The normal KL25Z ADC configuration is 16-bit quantization, so the
-    // quantization factor is usually 65535.  But you might prefer to set
-    // this to the joystick maximum so that there are no more rounding
-    // errors in scale conversions after the point of initial conversion.
-    //
-    // IMPORTANT!  This value MUST be initialized in the constructor for
-    // each concrete subclass.
-    int npix;
-         
     // Initialize the physical sensor device.  This is called at startup
     // to set up the device for first use.
     virtual void init() = 0;
 
     // Take a high-resolution reading.  Sets pos to the current position,
-    // on a scale from 0 to npix:  0 is the maximum forward plunger position,
-    // and npix is the maximum retracted position, in terms of the sensor's
+    // on a scale from 0.0 to 1.0:  0.0 is the maximum forward plunger position,
+    // and 1.0 is the maximum retracted position, in terms of the sensor's
     // extremes.  This is a raw reading in terms of the sensor range; the
     // caller is responsible for applying calibration data and scaling the
     // result to the the joystick report range.
     //
     // Returns true on success, false on failure.  Return false if it wasn't
     // possible to take a good reading for any reason.
-    virtual bool highResScan(int &pos) = 0;
+    virtual bool highResScan(float &pos) = 0;
 
     // Take a low-resolution reading.  This reports the result on the same
-    // 0..npix scale as highResScan().  Returns true on success, false on
+    // 0.0 to 1.0 scale as highResScan().  Returns true on success, false on
     // failure.
     //
     // The difference between the high-res and low-res scans is the amount 
@@ -67,7 +42,7 @@
     // The distinction is for the benefit of sensors that need significantly
     // longer to read at higher resolutions, such as image sensors that have
     // to sample pixels serially.
-    virtual bool lowResScan(int &pos) = 0;
+    virtual bool lowResScan(float &pos) = 0;
         
     // Send an exposure report to the joystick interface.  This is specifically
     // for image sensors, and should be omitted by other sensor types.  For