Diff: libraries/cn0357/cn0357.cpp

Revision:

1:c1f0670bb370

Child:

3:1a8c14043a4e

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libraries/cn0357/cn0357.cpp	Wed Mar 30 17:35:04 2016 +0300
@@ -0,0 +1,192 @@
+/**
+*   @file     CN0357.cpp
+*   @brief    Source file for CN0357 toxic gas sensor shield
+*   @version  V0.1
+*   @author   ADI
+*   @date     March 2015
+**/
+
+
+#include "mbed.h"
+#include "AD7790.h"
+#include "AD5270.h"
+#include "cn0357.h"
+
+/**
+ * @brief CN0357 constructor
+ * @param CSAD7790 - (optional)chip select of the AD7790
+ * @param CSAD5270 - (optional)chip select of the AD5270
+ * @param MOSI - (optional)pin of the SPI interface
+ * @param MISO - (optional)pin of the SPI interface
+ * @param SCK  - (optional)pin of the SPI interface
+ */
+CN0357::CN0357(PinName CSAD7790, PinName CSAD5270, PinName MOSI, PinName MISO,
+               PinName SCK) :
+    ad7790(CSAD7790, MOSI, MISO, SCK), ad5270(CSAD5270, 20000.0, MOSI, MISO, SCK) ,
+    _sensor_sensitivity(0), _sensor_range(0), _RDACvalue(0)
+{
+}
+
+/**
+ * @brief initializes the AD7790 and the AD5270
+ * @param range - range of the sensor used (in ppm)
+ * @param sensitivity - sensitivity of the sensor (A/ppm)
+ * @param jp - (optional)jumper configuration of the CN0357
+ * @param mode_val - (optional)if jp is set to InternalADC, configures the mode register of the Internal ADC
+ * @param filter_val - (optional)if jp is set to InternalADC, configures the filter register of the Internal ADC
+ */
+void CN0357::init(float range, float sensitivity,JumperConfig_t jp,uint8_t mode_val, uint8_t filter_val)
+{
+    ad5270.frequency(500000);
+    ad7790.frequency(500000);
+
+    float resistance = set_sensor_parameters(range,sensitivity);
+    _rdac_init(resistance);
+    if(jp == INTERNAL_AD7790) {
+        _AD7790_init(mode_val, filter_val);
+    }
+
+}
+
+/**
+ * @brief initializes the RDAC and sets SDO to HiZ
+ * @param resistance - resistance value to initialize the RDAC
+ * @return
+ */
+void CN0357::_rdac_init(float resistance)
+{
+    /* RDAC initialization*/
+    /* Compute for the nearest RDAC value from given resistance and save data to the structure */
+    set_RDAC_value(resistance);
+    /* Set AD5270 SDO to Hi-Z */
+    ad5270.set_SDO_HiZ();
+}
+
+/**
+ * @brief initializes the AD7790
+ * @param mode_val -  configures the mode register of the Internal ADC
+ * @param filter_val -  configures the filter register of the Internal ADC
+ */
+void CN0357::_AD7790_init(uint8_t mode_val, uint8_t filter_val)
+{
+    ad7790.reset();
+    // wait_ms(1000);
+    ad7790.write_reg(AD7790::MODE_REG, mode_val);
+    ad7790.write_reg(AD7790::FILTER_REG, filter_val);
+
+}
+
+/**
+ * @brief reads the status register of the AD7790
+ * @return status register value
+ */
+uint8_t CN0357::read_adc_status(void)
+{
+    return ad7790.read_reg(AD7790::STATUS_REG);
+}
+
+/**
+ * @brief reads the ADC and computes the sensor voltage
+ * @return sensor voltage
+ */
+float CN0357::read_sensor_voltage(void)
+{
+    return data_to_voltage(read_sensor());
+}
+
+/**
+ * @brief reads the data register of the AD7790
+ * @return data register value
+ */
+uint16_t CN0357::read_sensor(void)
+{
+    return ad7790.read_data();
+}
+
+/**
+ * @brief reads and computes the sensor reading in PPM
+ * @return value of the sensor reading in PPM
+ */
+float CN0357::read_ppm()
+{
+    return calc_ppm(read_sensor_voltage()); /* Convert voltage to Gas concentration*/
+}
+
+/**
+ * @brief computes a value in PPM from a reading received as a param
+ * @param adcVoltage - voltage to be converted to PPM
+ * @return sensor value in PPM
+ */
+float CN0357::calc_ppm(float adcVoltage)
+{
+    float fConcentration = 0;
+    fConcentration = (fabs(adcVoltage) / _RDACvalue) / _sensor_sensitivity;
+    return fConcentration;
+}
+
+/**
+ * @brief computes voltage from a 16 bit ADC value received as a parameter
+ * @param data - ADC value
+ * @return sensor voltage
+ */
+float CN0357::data_to_voltage(uint16_t data)
+{
+    return ((static_cast<float>(data) / pow(2, 15)) - 1) * 1.2; /* Bipolar voltage computation from ADC code */
+}
+
+/**
+ * @brief sets a new value for the RDAC
+ * @param resistance new value for the resistance
+ * @return none
+ */
+void CN0357::set_RDAC_value(float resistance)
+{
+    // Compute for the RDAC code nearest to the required feedback resistance
+    uint16_t RDAC_val = (resistance / 20000.0) * 1024.0;
+    // Compute for the constants used in voltage and PPM conversion computation
+    _RDACvalue = ((static_cast<float> (RDAC_val) * 20000.0) / 1024.0);
+    ad5270.write_cmd(AD5270::WRITE_CTRL_REG, 0x02); // RDAC register write protect -  allow update of wiper position through digital interface
+    ad5270.write_cmd(AD5270::WRITE_RDAC, RDAC_val); // write data to the RDAC register
+}
+
+/**
+ * @brief getter method for RDAC value
+ * @return value of the RDAC in ohms
+ */
+float CN0357::get_RDAC_value()
+{
+    return _RDACvalue;
+}
+
+/**
+ * @brief set sensor range and sensitivity
+ * sets sensor range, sensitivity
+ * returns suggested resistance value for feedback resistor
+ * @param range - range of the sensor used (in ppm)
+ * @param sensitivity - sensitivity of the sensor (in A/ppm)
+ * @return suggested resistance value for feedback resistor
+ */
+float CN0357::set_sensor_parameters(float range, float sensitivity)
+{
+    _sensor_sensitivity = static_cast<float>(sensitivity);
+    _sensor_range = range;
+    return (1.2 / (static_cast<float>(_sensor_range * _sensor_sensitivity)));
+}
+
+/**
+ * @brief getter method for sensor sensitivity
+ * @return sensor sensitivity (in A/ppm)
+ */
+float CN0357::get_sensor_sensitivity()
+{
+    return _sensor_sensitivity;
+}
+
+/**
+ * @brief getter method for sensor range
+ * @return sensor range (in ppm)
+ */
+float CN0357::get_sensor_range()
+{
+    return _sensor_range;
+}