Diff: LinearTempSensor.cpp

Revision:

0:4b56d28cc7e9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/LinearTempSensor.cpp	Wed Dec 02 11:39:52 2015 +0000
@@ -0,0 +1,92 @@
+/* mbed Linear Temperature Sensor library
+ * Supports Microchip MCP9700/9701, National Semiconductor LM35
+ *
+ * Written by Todotani, Nov 22 2010
+ */
+
+#include "LinearTempSensor.h"
+
+LinearTempSensor::LinearTempSensor(PinName ain, int N, SensorType type):
+        // Initialize private variables using Initialization Lists
+        // _ain(ain) is equivalent to _ain = new AnalogIn(ain)
+        // _sample(N) is equivalent to _sample = N
+        _ain(ain), _samples(N), _type(type) {
+    sampleBuffer = (float *)malloc(sizeof(float) * _samples);
+    sampleCount = 0;
+    index       = 0;
+    Vref        = 3300;
+    bufferNotFilled = true;
+
+    // Set constants to calculate temperature from sensor value
+    switch (_type) {
+        case LM35:
+            V0 = 0.0f;
+            Tc = 10.0f;
+            break;
+      case MCP9701:
+            V0 = 400.0f;
+            Tc = 19.5f;
+            break;
+      case MCP9700:
+       default:
+            V0 = 500.0f;
+            Tc = 10.0f;
+    }
+    
+    for (int i = 0; i < _samples; i++)
+        sampleBuffer[i] = 0.0f;
+}
+
+
+LinearTempSensor::~LinearTempSensor() {
+    free(sampleBuffer);
+}
+
+
+float LinearTempSensor::Sense() {
+    float val;
+
+    val = _ain * Vref;
+    sampleBuffer[index] = val;
+    //printf("Index:%d  ", index);    // Debug print
+    if ( ++index >= _samples )
+        index = 0;
+
+    if ( bufferNotFilled && (sampleCount == _samples) ) {
+        bufferNotFilled = false;
+    }
+    //printf("flag:%d  ", bufferNotFilled);   // Debug print
+    sampleCount++;
+
+    return val;
+}
+
+
+float LinearTempSensor::GetAverageTemp() {
+    float sum = 0;
+    int i, numberOfsumples;
+
+    if (sampleCount == 0)
+        return 0;
+
+    if (bufferNotFilled) {
+        // In case number of samples less than buffer lenght
+        for (i = 0; i < sampleCount; i++) {
+            sum += sampleBuffer[i];
+        }
+        numberOfsumples = sampleCount;
+    } else {
+        // In case buffer is filled
+        for (i = 0; i < _samples; i++) {
+            sum += sampleBuffer[i];
+        }
+        numberOfsumples = _samples;
+    }
+
+    return ((sum / numberOfsumples) - V0) / Tc;    //  Temp = (Vout - V0) / Tc
+}
+
+
+float LinearTempSensor::GetLatestTemp() {
+    return (sampleBuffer[(sampleCount-1)%_samples] - V0) / Tc;
+}