A component library for MiCS-6814 Multichannel Gas Sensor (seeed)
Dependents: MiCS6814_GasSensor_Hello grove_multichannel_GasSensor
MiCS6814_GasSensor.cpp
- Committer:
- MACRUM
- Date:
- 2017-05-24
- Revision:
- 3:93b7f86b72e1
- Parent:
- 1:5caeba593de4
File content as of revision 3:93b7f86b72e1:
/** ****************************************************************************** * @file MiCS6814_GasSensor.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. */ #include "mbed.h" #include "MiCS6814_GasSensor.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(HEATER_OFF); // 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 (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); wait(0.1f); _i2c.read(_address, val, read_len); if (read_len==2) { *ret_val = (uint16_t) (val[0]<<8 | val[1]) ; // set return value to caller 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 ); } } 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(const unsigned char Switch_On) { char tmp[2]; DEBUG_PRINT("Sensor heater Power :%s\r\n", Switch_On==1? "On":"Off"); tmp[0] = CMD_CONTROL_PWR; tmp[1] = Switch_On; _i2c.write(_address, tmp, 2); wait(0.1f); } uint16_t MiCS6814_GasSensor::readR0_A0(unsigned char index) { 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; ret_val= read_Multibytes(CMD_READ_EEPROM, A0_table[index], 2, 2, &readBuf); DEBUG_PRINT("A0_[%d]: %d, ", index, readBuf); if (ret_val == READ_OK) { return readBuf; } // read failed, A0_[index] DEBUG_PRINT("A0_[%d] read error: %d\r\n", index, ret_val); return 0; } uint16_t MiCS6814_GasSensor::readRs_An(unsigned char index) { uint16_t readBuf= 0; const unsigned char An_table[3]= {CH_VALUE_NH3, CH_VALUE_CO, CH_VALUE_NO2}; unsigned char ret_val; ret_val= read_Multibytes(An_table[index], 0, 1, 2, &readBuf); DEBUG_PRINT("An_[%d]: %d, ", index, readBuf); if (ret_val == READ_OK) { return readBuf; } // read failed, An_[index] DEBUG_PRINT("An_[%d] read error: %d\r\n", index, ret_val); return 0; } float MiCS6814_GasSensor::getGas(const GAS_TYPE gas_type) { int A0_[3], An_[3]; const unsigned char GasType_2index[8] = {0, 1, 2, 0, 0, 1, 1, 1}; unsigned char index = GasType_2index[gas_type]; float Ratio[3]; //will be calculated. Ratio 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(HEATER_ON); // turn on the heater. }