Revision 1:f5f2e79304fb, committed 2011-06-09

Comitter:

aberk

Date:

Thu Jun 09 14:29:16 2011 +0000

Parent:

0:fe041345c169

Commit message:

Added functionality for getting the acceleration values in raw counts as opposed to milli-gs.

Changed in this revision

--- a/SCA3000.cpp	Sun May 29 14:13:20 2011 +0000
+++ b/SCA3000.cpp	Thu Jun 09 14:29:16 2011 +0000
@@ -73,6 +73,12 @@
 
 float SCA3000::getAcceleration(int axis) {
 
+    return getCounts(axis) * 0.75;
+
+}
+
+int SCA3000::getCounts(int axis){
+
     int acceleration = 0;
     int axis_lsb     = 0;
     int axis_msb     = 0;
@@ -107,30 +113,22 @@
 
     }
 
-    acceleration = ( axis_msb << 8 | axis_lsb );
-
-    return countsToMg(acceleration);
-
-}
-
-float SCA3000::countsToMg(int counts){
-
-    float acceleration = 0.0;
-
+    int counts = ( axis_msb << 8 | axis_lsb );
+    
     //If this looks like nonsense it's because
     //the datasheet is completely wrong.
     if(counts & 0x8000){
         counts = (counts >> 3) & 0x1FFF;
-        counts = (~counts & 0x1FFF)+ 1;
-        acceleration = counts * -0.75;
+        counts = (~counts & 0x1FFF) + 1;
+        acceleration = counts * -1;
     }
     else{
         counts = (counts >> 3) & 0xFFF;
-        acceleration = counts * 0.75;
+        acceleration = counts;
     }
     
     return acceleration;
-
+    
 }
 
 int SCA3000::oneByteRead(int address) {

--- a/SCA3000.h	Sun May 29 14:13:20 2011 +0000
+++ b/SCA3000.h	Thu Jun 09 14:29:16 2011 +0000
@@ -85,13 +85,24 @@
     
     /**
      * Get the register contents acceleration value for the
-     * given axis.
+     * given axis, using the nominal sensitivity values
+     * found in the datasheet.
      *
      * @param axis The axis to get acceleration values for.
      *
      * @return The acceleration on the specified axis in mg.
      */
     float getAcceleration(int axis);
+    
+    /**
+     * Get the register contents acceleration value for the
+     * given axis, in counts.
+     *
+     * @param axis The axis to get the counts values for.
+     *
+     * @return The acceleration on the specified axis in counts.
+     */
+    int getCounts(int axis);
 
 private:
 
@@ -100,16 +111,6 @@
     DigitalOut nR_;
     
     /**
-     * Converts the contents of acceleration registers (MSB << 8 | LSB)
-     * to mg.
-     * 
-     * @param counts The contents of acceleration registers.
-     *
-     * @return The acceleration in mg.
-     */
-    float countsToMg(int counts);
-    
-    /**
      * Read one byte from a register on the device.
      *
      * @param address Address of the register to read.