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