Diff: multigas_sensor.cpp

Revision:

0:e0794665caf1

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/multigas_sensor.cpp	Wed May 24 01:43:23 2017 +0000
@@ -0,0 +1,236 @@
+/**
+ ******************************************************************************
+ * @file    multigas_sensor.cpp
+ * @author  Boting Ren
+ * @version V1.0.1
+ * @date    22 May 2017
+ * @brief   MiCS6814_GasSensor class implementation
+ ******************************************************************************
+ * @attention
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @par     History
+ * - 19 May 2017, V1.0.0, Boting Ren
+ * - 22 May 2017, V1.0.1, Boting Ren
+ * 1. changed class name and private variables name
+ * 2. removed printf output
+ * 3. removed removed timer and Cache feature
+ * 4. removed code working for version 1 firmware
+ * 5. moved class private variables into member functions
+ * 6. other small improvements
+ *
+ */
+#include "mbed.h"
+#include "multigas_sensor.h"
+
+MiCS6814_GasSensor::MiCS6814_GasSensor(PinName sda, PinName scl, char slave_adr)
+    :
+    _i2c_p(new I2C(sda, scl)),
+    _i2c(*_i2c_p),
+    _address(slave_adr)
+{
+    initialize();
+}
+
+MiCS6814_GasSensor::MiCS6814_GasSensor(I2C &i2c_obj, char slave_adr)
+    :
+    _i2c_p(NULL),
+    _i2c(i2c_obj),
+    _address(slave_adr)
+{
+    initialize();
+}
+
+MiCS6814_GasSensor::~MiCS6814_GasSensor()
+{
+    HeaterPower(false);    // turn off the heater
+    if (NULL != _i2c_p)
+    {
+        delete  _i2c_p;
+    }
+}
+
+
+READ_ERROR_TYPE MiCS6814_GasSensor::read_Multibytes(unsigned char addr_reg, unsigned char __dta, unsigned char write_len, unsigned char read_len, uint16_t * ret_val)
+{
+    char cmd[2], val[4];     // write buf, read buf
+    uint8_t checksum=0;
+
+    if (ret_val==NULL) {
+        return NULL_RETURN_BUFFER_PTR;     // ret_val is a NULL pointer
+    }
+    if(write_len>2 || write_len<1) {
+        return WRITE_LENGTH_ERROR;         // write_len is wrong
+    }
+    if (read_len!=2 && read_len!=4) {
+        return READ_LENGTH_ERROR;          // read_len is wrong
+    }
+    *ret_val=0;     // clear return buf
+
+    cmd[0] = addr_reg;
+    if (write_len==2) {
+        cmd[1] = __dta;
+    }
+    _i2c.write(_address, cmd, write_len);
+
+    _i2c.read(_address, val, read_len);
+
+    if (read_len==2) {
+        *ret_val = (uint16_t) (val[0]<<8 | val[1]) ;   // set return value to caller
+        #ifdef _DEBUG
+        if(*ret_val==0)  DEBUG_PRINT("read_Multibytes, *ret_val=0, addr_reg: 0x%x, write_len: %x, read_len: %x\r\n", addr_reg, write_len, read_len );
+        #endif
+    }else if (read_len==4) {
+        checksum = (uint8_t)(val[0] + val[1] + val[2]);
+        if(checksum != val[3]){
+            DEBUG_PRINT("checksum failed,   val[4]: 0x%x,   0x%x,   0x%x,   0x%x, checksum: 0x%x\r\n", val[0], val[1], val[2], val[3], checksum );
+            DEBUG_PRINT("checksum failed i2c.read, addr_reg: 0x%x, write_len: %x, read_len: %x\r\n", addr_reg, write_len, read_len );
+            return CHECKSUM_ERROR;    //checksum is wrong
+        }
+        *ret_val = (uint16_t) ((val[1] << 8) + val[2]);
+    }
+    return READ_OK;
+}
+
+void MiCS6814_GasSensor::CheckFirmwareVersion()
+{
+    uint16_t readBuf=0;
+    unsigned char ret_val = read_Multibytes(CMD_READ_EEPROM, ADDR_IS_SET, 2, 2, &readBuf);      // read firmware version
+    // only support version = 2
+    MBED_ASSERT(ret_val == READ_OK && readBuf == 1126);
+}
+
+
+void MiCS6814_GasSensor::HeaterPower(bool Switch_On)
+{
+    const unsigned char v2tmp[2]={0, 1};        // On, Off command for version 2
+    char tmp[4];
+    DEBUG_PRINT("Sensor heater Power :%s\r\n", Switch_On? "On":"Off");
+    tmp[0] = 11;
+    tmp[1] = v2tmp[Switch_On];
+    _i2c.write(_address, tmp, 2);
+}
+
+uint16_t MiCS6814_GasSensor::readR0_A0(unsigned char _indix)
+{
+    uint16_t readBuf=0;
+    const unsigned char A0_table[3]={ADDR_USER_ADC_HN3, ADDR_USER_ADC_CO, ADDR_USER_ADC_NO2};
+    unsigned char ret_val;
+    //  version 2 : read A0_[_indix]
+    ret_val= read_Multibytes(CMD_READ_EEPROM, A0_table[_indix], 2, 2, &readBuf);
+    DEBUG_PRINT("A0_[%d]: %d,    ", _indix, readBuf);
+    if (ret_val == READ_OK) {
+        return readBuf;
+    }
+    // read failed, Rs[_indix]
+    DEBUG_PRINT("A0_[%d] read error: %d\r\n", _indix, ret_val);
+    return 0;
+}
+
+
+uint16_t MiCS6814_GasSensor::readRs_An(unsigned char _indix)
+{
+    uint16_t readBuf=0;
+    const unsigned char An_table[3]={CH_VALUE_NH3, CH_VALUE_CO, CH_VALUE_NO2};
+    unsigned char ret_val;
+    //  version 2 : read An_[_indix]
+    ret_val= read_Multibytes(An_table[_indix], 0, 1, 2, &readBuf);
+    DEBUG_PRINT("An_[%d]: %d,    ", _indix, readBuf);
+    if (ret_val == READ_OK) {
+        return readBuf;
+    }
+    // read failed, Rs[_indix]
+    DEBUG_PRINT("An_[%d] read error: %d\r\n", _indix, ret_val);
+    return 0;
+}
+
+
+float MiCS6814_GasSensor::calcGas(const GAS_TYPE gas_type)
+{
+    int A0_[3], An_[3];
+    const unsigned char GasType_2index[8] ={/* NH3 */ 0,/* CO */ 1,/* NO2 */ 2,/*C3H8 */ 0,/* C4H10 */ 0,/* CH4 */ 1,/* H2 */ 1,/* C2H5OH */ 1};
+    unsigned char _index = GasType_2index[gas_type];
+    float Ratio[3];        //will be calculated. ration 0,1,2
+
+    // prepare necessary Ratio[x] according to gas_type
+    An_[_index] = readRs_An(_index);      // read An_[x]
+    A0_[_index] = readR0_A0(_index);      // read R0[x]
+    Ratio[_index] = (float)An_[_index]/(float)A0_[_index]*(1023.0-A0_[_index])/(1023.0-An_[_index]);
+    DEBUG_PRINT("Ratio[%d]: %.3f,   ", _index, Ratio[_index]);
+
+    float calcu_val = 0.0f;
+    // calculate concentration value of specified gas_type
+    switch(gas_type)
+    {
+        case CO:
+        {
+            calcu_val = pow(Ratio[1], -1.179f)*4.385f;
+            break;
+        }
+        case NO2:
+        {
+            calcu_val = pow(Ratio[2], 1.007f)/6.855f;
+            break;
+        }
+        case NH3:
+        {
+            calcu_val = pow(Ratio[0], -1.67f)/1.47f;
+            break;
+        }
+        case C3H8:
+        {
+            calcu_val = pow(Ratio[0], -2.518f)*570.164f;
+            break;
+        }
+        case C4H10:
+        {
+            calcu_val = pow(Ratio[0], -2.138f)*398.107f;
+            break;
+        }
+        case CH4:
+        {
+            calcu_val = pow(Ratio[1], -4.363f)*630.957f;
+            break;
+        }
+        case H2:
+        {
+            calcu_val = pow(Ratio[1], -1.8f)*0.73f;
+            break;
+        }
+        case C2H5OH:
+        {
+            calcu_val = pow(Ratio[1], -1.552f)*1.622f;
+            break;
+        }
+        default:
+            break;
+    }
+
+    return calcu_val;
+}
+
+
+
+void MiCS6814_GasSensor::initialize()
+{
+
+    CheckFirmwareVersion();
+    HeaterPower(true);   // turn on the heater.
+}