LinearTempSensor.h

00001 /* mbed Linear Temperature Sensor library
00002  * Supports Microchip MCP9700/9701, National Semiconductor LM35
00003  *
00004  * Written by Todotani, Nov 22 2010
00005  */
00006  
00007 #ifndef MBED_LINEARTEMPSENSOR_H
00008 #define MBED_LINEARTEMPSENSOR_H
00009 
00010 #include "mbed.h"
00011 
00012 /** Linear Temperature Sensor class.
00013  * Sample and store sensor acuired value in N (default=10) times and
00014  * calculate avarage temperature from sampled data
00015  * Supports Microchip MCP9700/9701, National Semiconductor LM35
00016  * @author Todotani
00017  */
00018 class LinearTempSensor {
00019 public:
00020     /** Sensor Type Definitions  */
00021     enum SensorType {
00022         MCP9700,    /**< Microchip MCP9700 (Default)  */
00023         MCP9701,    /**< Microchip MCP9701 */
00024         LM35        /**< National Semiconductor LM35 */
00025     };
00026     
00027     /** Create a Temperature Sensor instanse
00028      *
00029      * @param ain       PinName of analog input
00030      * @param N         Number of samples to calculate average temperature (default = 10)
00031      * @param type      Sensor type (default = MCP9700)
00032      */
00033     LinearTempSensor(PinName ain, int N = 10, SensorType type = MCP9700);
00034     
00035     /** Sample (read) sensor data and store to buffer
00036      *
00037      * @param None
00038      * @return Sensor-acuired value (mV)
00039      */
00040      float Sense();
00041      
00042     /** Calculate average temperature from sample buffer
00043      *
00044      * @param None
00045      * @return Average temperature from N times of sumple (Centigrade)
00046      */
00047      float GetAverageTemp();
00048      
00049     /** Calculate temperature from the latest sample
00050      *
00051      * @param None
00052      * @return Temperature from the latest sampled data (Centigrade)
00053      */
00054      float GetLatestTemp();
00055 
00056      ~LinearTempSensor();
00057 
00058 private:
00059     AnalogIn    _ain;
00060     int         _samples;
00061     SensorType  _type;
00062     
00063     float       *sampleBuffer;      // Buffer to store sensor acuired data
00064     bool        bufferNotFilled;    // Flag shows that buffer have not filled
00065     uint32_t    sampleCount;
00066     uint32_t    index;
00067 
00068     float   V0;                      // Sensor read value in case 0 degree
00069     float   Tc;                      // Tmperature coefficient (temprature inclease) in each degree
00070     float   Vref;                    // Reference volgate for ADC
00071 };
00072 
00073 #endif