Diff: LinearAnalogSensor.cpp

Revision:

0:78eeca1c1944

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/LinearAnalogSensor.cpp	Wed Aug 07 19:37:12 2013 +0000
@@ -0,0 +1,66 @@
+/* Copyright (c) <2012> <P. Patel>, MIT License
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software 
+ * and associated documentation files (the "Software"), to deal in the Software without restriction, 
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute, 
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is 
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or 
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING 
+ * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+ 
+// --------------------- Median Filtered Linear Temperature Sensor Reader ----------------------------
+ 
+#include "LinearAnalogSensor.h"
+#include "mbed.h"
+
+// Constructor using two calibration points to define linear multiplier and offset
+LinearAnalogSensor::LinearAnalogSensor(PinName pin, int numSamples, float temp1, unsigned short read1, float temp2, unsigned short read2):_pin(pin) {
+    _reading = 0.0;                                     // Zero the temperature
+    _multiplier = (temp2 - temp1) / (read2 - read1); // Calculate multiplier as slope
+    _offset = temp1 - (_multiplier * read1);         // Calculate offset
+    _numSamples = numSamples;
+    _arr = new unsigned short[numSamples];
+}
+// Constructor using user defined multiplier and offset
+LinearAnalogSensor::LinearAnalogSensor(PinName pin, int numSamples, float multiplier, float offset):_pin(pin) {
+    _reading = 0.0;                                     // Zero the temperature
+    _multiplier = multiplier;                        // Set multiplier
+    _offset = offset;                                // Set offset
+    _numSamples = numSamples;
+    _arr = new unsigned short[numSamples];
+}
+
+// Populates an array with temperature readings, sorts, and returns median
+float LinearAnalogSensor::read() {
+    memset(_arr, 0, _numSamples * sizeof(unsigned short));
+    _arr[0] = _pin.read_u16();
+    for (int i = 1; i < _numSamples; i++) { 
+        _arr[i] = _pin.read_u16();
+        unsigned short tmp = _arr[i];
+        int j;            
+        for (j = i - 1; j >= 0; j--) {
+            if (tmp>=_arr[j]) break;
+            _arr[j + 1] = _arr[j];
+        }
+        _arr[j + 1] = tmp;
+    }
+    if (_numSamples % 2 == 0) {
+        _reading = (((_arr[_numSamples >> 1] + _arr[(_numSamples >> 1) - 1]) / (2.0)) * _multiplier) + _offset;
+    }
+    if (_numSamples % 2 == 1)  {
+        _reading = (_arr[_numSamples >> 1] * _multiplier) + _offset;
+    }
+    return _reading;
+}
+// Returns last calculated temperature value
+float LinearAnalogSensor::getLast() {
+    return _reading;
+}
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