CN0396.h

00001 #ifndef _CN0396_H_
00002 #define _CN0396_H_
00003 #include <mbed.h>
00004 #include "AD7798.h"
00005 #include "AD5270.h"
00006 #include "ADT7310.h"
00007 
00008 /**
00009  * @brief The CN0396 class
00010  */
00011 class CN0396
00012 {
00013 public:
00014 
00015 #define V_REF                1.200    // [V]
00016 #define _2_16                65535.0   // 2^16
00017 #define _2_15                32767.0   // 2^16
00018 #define COMPENSATION_TABLE_SIZE 9
00019 
00020     typedef enum {
00021         CO_SENSOR,
00022         H2S_SENSOR
00023     } sensor_type_t;
00024 
00025     typedef struct {
00026         int8_t temp;
00027         float CO_percent;
00028         float H2S_percent;
00029     } ppm_compensation_t;
00030 
00031     /**
00032      *  @brief compensation look-up table
00033      */
00034     const ppm_compensation_t ppm_compensation[COMPENSATION_TABLE_SIZE] = {
00035         { -30   , 29.9  , 82.3 },
00036         { -20   , 38.8  , 84.6 },
00037         { -10   , 53.7  , 88.6 },
00038         {0      , 69.6  , 92.2 },
00039         {10     , 84.9  , 96.2 },
00040         {20     , 100.0 , 100.0},
00041         {30     , 112.7 , 103.1},
00042         {40     , 123.7 , 105.6},
00043         {50     , 133.1 , 107.4}
00044     };
00045 
00046 
00047     /**
00048      * @brief CN0396 class constructor
00049      * @param csad  - chipselect pin of the ADC
00050      * @param csrdac - chipselect pin of the RDAC
00051      * @param cstemp - chipselect pin of the temperature sensor
00052      */
00053     CN0396(PinName csad, PinName csrdac, PinName cstemp);
00054     /**
00055      * @brief Initializes the board
00056      */
00057     void init();
00058 
00059     /**
00060      * @brief - Reads the sensor and computes the PPM values
00061      */
00062     void read();
00063 
00064     /**
00065      * @brief computes the feedback resistor value for the sensor
00066      * @param sensitivity - sensor sensitivity
00067      * @param range - sensor range
00068      * @return resistor value
00069      */
00070     float get_feedback_resistor_value(float sensitivity, float range);
00071 
00072     /**
00073      * @brief configures the RDACs with the resistance values
00074      * @param resistance1 - resistance of RDAC1
00075      * @param resistance2 - resistance of RDAC2
00076      * @return
00077      */
00078     void configure_feedback_resistors(float resistance1, float resistance2);
00079 
00080     /**
00081     * @brief computes ADC counts-to-voltage in unipolar configuration
00082     * @param adcValue - value in counts
00083     * @param voltage - voltage value returned by the method
00084     * @param gain_adc - the gain of the adc
00085     */
00086     void data_to_voltage(uint16_t adcValue, float *voltage, int gain_adc = 1);
00087 
00088     /**
00089      * @brief computes ADC counts-to-voltage in bipolar configuration
00090      * @param adcValue - value in counts
00091      * @param voltage - voltage value returned by the method
00092      * @param gain_adc - the gain of the adc
00093      */
00094     void data_to_voltage_bipolar(uint16_t adcValue, float *voltage, int gain_adc = 1);
00095 
00096     /**
00097      * @brief compensates ppm value based on temperature reading
00098      * @param result - ppm value before compensation
00099      * @param temp - temperature used in compensation
00100      * @param sensor - sensor id
00101      * @return compensated value
00102      */
00103     float compensate_ppm(float result, float temp, sensor_type_t sensor);
00104     DigitalOut csad, csrdac, cstemp;
00105     AD7798 ad;
00106     AD5270 rdac;
00107     ADT7310 temp;
00108     float resistance0, resistance1;
00109 private:
00110 
00111 
00112 };
00113 #endif