A component library for MiCS-6814 Multichannel Gas Sensor (seeed)
Dependents: MiCS6814_GasSensor_Hello grove_multichannel_GasSensor
Diff: multigas_sensor.cpp
- Revision:
- 0:e0794665caf1
diff -r 000000000000 -r e0794665caf1 multigas_sensor.cpp --- /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. +}