BME280_MOD-1022.cpp

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// BME280 MOD-1022 weather multi-sensor Arduino library
// Written originally by Embedded Adventures

#include "BME280_MOD-1022.h"
#include "Wire.h"

// Returns temperature in DegC, double precision. Output value of “51.23” equals 51.23 DegC.
// t_fine carries fine temperature as global value

double BME280Class::BME280_compensate_T_double(BME280_S32_t adc_T) {

double var1, var2, T;

  var1 = (((double)adc_T)/16384.0 - ((double)compParams.compStruct.dig_T1)/1024.0) * ((double)compParams.compStruct.dig_T2);
  var2 = ((((double)adc_T)/131072.0 - ((double)compParams.compStruct.dig_T1)/8192.0) *
  (((double)adc_T)/131072.0 - ((double) compParams.compStruct.dig_T1)/8192.0)) * ((double)compParams.compStruct.dig_T3);
  t_fine = (BME280_S32_t)(var1 + var2);
  T = (var1 + var2) / 5120.0;
  return T;
}

// Returns pressure in Pa as double. Output value of “96386.2” equals 96386.2 Pa = 963.862 hPa
double BME280Class::BME280_compensate_P_double(BME280_S32_t adc_P) {
  
double var1, var2, p;

  var1 = ((double)t_fine/2.0) - 64000.0;
  var2 = var1 * var1 * ((double)compParams.compStruct.dig_P6) / 32768.0;
  var2 = var2 + var1 * ((double)compParams.compStruct.dig_P5) * 2.0;
  var2 = (var2/4.0)+(((double)compParams.compStruct.dig_P4) * 65536.0);
  var1 = (((double)compParams.compStruct.dig_P3) * var1 * var1 / 524288.0 + ((double)compParams.compStruct.dig_P2) * var1) / 524288.0;
  var1 = (1.0 + var1 / 32768.0)*((double)compParams.compStruct.dig_P1);
  if (var1 == 0.0) {
    return 0; // avoid exception caused by division by zero
  }
  p = 1048576.0 - (double)adc_P;
  p = (p - (var2 / 4096.0)) * 6250.0 / var1;
  var1 = ((double)compParams.compStruct.dig_P9) * p * p / 2147483648.0;
  var2 = p * ((double)compParams.compStruct.dig_P8) / 32768.0;
  p = p + (var1 + var2 + ((double)compParams.compStruct.dig_P7)) / 16.0;
  return p;
}

// Returns humidity in %rH as as double. Output value of “46.332” represents 46.332 %rH
double BME280Class::BME280_compensate_H_double(BME280_S32_t adc_H) {

 double var_H;
 
  var_H = (((double)t_fine) - 76800.0);
  var_H = (adc_H - (((double)compParams.compStruct.dig_H4) * 64.0 + ((double)compParams.compStruct.dig_H5) / 16384.0 * var_H)) *
          (((double)compParams.compStruct.dig_H2) / 65536.0 * (1.0 + ((double)compParams.compStruct.dig_H6) / 67108864.0 * var_H *
          (1.0 + ((double)compParams.compStruct.dig_H3) / 67108864.0 * var_H)));
  var_H = var_H * (1.0 - ((double)compParams.compStruct.dig_H1) * var_H / 524288.0);
  if (var_H > 100.0) {
    var_H = 100.0;
  } else if (var_H < 0.0) {
    var_H = 0.0;
  }  
  return var_H;
}

// Returns pressure in Pa as unsigned 32 bit integer. Output value of “96386” equals 96386 Pa = 963.86 hPa
BME280_U32_t BME280Class::BME280_compensate_P_int32(BME280_S32_t adc_P)
{
BME280_S32_t var1, var2;
BME280_U32_t p;
  var1 = (((BME280_S32_t)t_fine)>>1) - (BME280_S32_t)64000;
  var2 = (((var1>>2) * (var1>>2)) >> 11 ) * ((BME280_S32_t)compParams.compStruct.dig_P6);
  var2 = var2 + ((var1*((BME280_S32_t)compParams.compStruct.dig_P5))<<1);
  var2 = (var2>>2)+(((BME280_S32_t)compParams.compStruct.dig_P4)<<16);
  var1 = (((compParams.compStruct.dig_P3 * (((var1>>2) * (var1>>2)) >> 13 )) >> 3) + ((((BME280_S32_t)compParams.compStruct.dig_P2) * var1)>>1))>>18;
  var1 =((((32768+var1))*((BME280_S32_t)compParams.compStruct.dig_P1))>>15);
  if (var1 == 0) {
    return 0; // avoid exception caused by division by zero
  }
  p = (((BME280_U32_t)(((BME280_S32_t)1048576)-adc_P)-(var2>>12)))*3125;
  if (p < 0x80000000) {
    p = (p << 1) / ((BME280_U32_t)var1);
  } else {
    p = (p / (BME280_U32_t)var1) * 2;
  }
  var1 = (((BME280_S32_t)compParams.compStruct.dig_P9) * ((BME280_S32_t)(((p>>3) * (p>>3))>>13)))>>12;
  var2 = (((BME280_S32_t)(p>>2)) * ((BME280_S32_t)compParams.compStruct.dig_P8))>>13;
  p = (BME280_U32_t)((BME280_S32_t)p + ((var1 + var2 + compParams.compStruct.dig_P7) >> 4));
  return p;
}

// Returns temperature in DegC, resolution is 0.01 DegC. Output value of “5123” equals 51.23 DegC.
// t_fine carries fine temperature as global value

int32_t BME280Class::BME280_compensate_T_int32(BME280_S32_t adc_T)
{
BME280_S32_t var1, var2, T;

  var1 = ((((adc_T>>3) -((BME280_S32_t)compParams.compStruct.dig_T1<<1))) * ((BME280_S32_t)compParams.compStruct.dig_T2)) >> 11;
  var2 = (((((adc_T>>4) - ((BME280_S32_t)compParams.compStruct.dig_T1)) * ((adc_T>>4) - ((BME280_S32_t)compParams.compStruct.dig_T1))) >> 12) * ((BME280_S32_t)compParams.compStruct.dig_T3)) >> 14;
  t_fine = var1 + var2;
  T = (t_fine * 5 + 128) >> 8;
  return T;
}

// Returns pressure in Pa as unsigned 32 bit integer in Q24.8 format (24 integer bits and 8 fractional bits).
// Output value of “24674867” represents 24674867/256 = 96386.2 Pa = 963.862 hPa
uint32_t BME280Class::BME280_compensate_P_int64(BME280_S32_t adc_P)
{
BME280_S64_t var1, var2, p;

  var1 = ((BME280_S64_t)t_fine) - 128000;
  var2 = var1 * var1 * (BME280_S64_t)compParams.compStruct.dig_P6;
  var2 = var2 + ((var1*(BME280_S64_t)compParams.compStruct.dig_P5)<<17);
  var2 = var2 + (((BME280_S64_t)compParams.compStruct.dig_P4)<<35);
  var1 = ((var1 * var1 * (BME280_S64_t)compParams.compStruct.dig_P3)>>8) + ((var1 * (BME280_S64_t)compParams.compStruct.dig_P2)<<12);
  var1 = (((((BME280_S64_t)1)<<47)+var1))*((BME280_S64_t)compParams.compStruct.dig_P1)>>33;
  if (var1 == 0) {
    return 0; // avoid exception caused by division by zero
  }
  p = 1048576-adc_P;
  p = (((p<<31)-var2)*3125)/var1;
  var1 = (((BME280_S64_t)compParams.compStruct.dig_P9) * (p>>13) * (p>>13)) >> 25;
  var2 = (((BME280_S64_t)compParams.compStruct.dig_P8) * p) >> 19;

  p = ((p + var1 + var2) >> 8) + (((BME280_S64_t)compParams.compStruct.dig_P7)<<4);
  return (BME280_U32_t)p;
}

// Returns humidity in %RH as unsigned 32 bit integer in Q22.10 format (22 integer and 10 fractional bits).
// Output value of “47445” represents 47445/1024 = 46.333 %RH
BME280_U32_t BME280Class::BME280_compensate_H_int32(BME280_S32_t adc_H)
{
BME280_S32_t v_x1_u32r;
  v_x1_u32r = (t_fine - ((BME280_S32_t)76800));
  v_x1_u32r = (((((adc_H << 14) - (((BME280_S32_t)compParams.compStruct.dig_H4) << 20) - (((BME280_S32_t)compParams.compStruct.dig_H5) * v_x1_u32r)) +
    ((BME280_S32_t)16384)) >> 15) * (((((((v_x1_u32r * ((BME280_S32_t)compParams.compStruct.dig_H6)) >> 10) * (((v_x1_u32r *
    ((BME280_S32_t)compParams.compStruct.dig_H3)) >> 11) + ((BME280_S32_t)32768))) >> 10) + ((BME280_S32_t)2097152)) *
    ((BME280_S32_t)compParams.compStruct.dig_H2) + 8192) >> 14));
  v_x1_u32r = (v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) * ((BME280_S32_t)compParams.compStruct.dig_H1)) >> 4));
  v_x1_u32r = (v_x1_u32r < 0 ? 0 : v_x1_u32r);
  v_x1_u32r = (v_x1_u32r > 419430400 ? 419430400 : v_x1_u32r);
  return (BME280_U32_t)(v_x1_u32r>>12);
}


float  BME280Class::getTemperature(void) {
  return (float)BME280_compensate_T_int32(adc_t) / 100;
}

double BME280Class::getTemperatureMostAccurate(void) {
  return BME280_compensate_T_double(adc_t);
}


float BME280Class::getHumidity(void) {
  return (float)BME280_compensate_H_int32(adc_h) / 1024;
}

double BME280Class::getHumidityMostAccurate(void) {
  return BME280_compensate_H_double(adc_h);
}

float BME280Class::getPressure(void) {
  return (float)BME280_compensate_P_int32(adc_p) / 100;
}

float BME280Class::getPressureMoreAccurate(void) {
  return (float)BME280_compensate_P_int64(adc_p) / 256 / 100;
} 

double BME280Class::getPressureMostAccurate(void) {
  return BME280_compensate_P_double(adc_p) / 100;
}


void BME280Class::writeStandbyTime(standbySettings_e t_sb) {

uint8_t conf;

  conf = readRegister(regConfig);  // Status is hidden in here
  // We want to change osrs_p which is bits 4,3,2
  conf = conf & 0b00011111; // mask out the bits we care about
  conf = conf | (t_sb << 5); // Set the magic bits

  writeRegister(regConfig, conf);

}   

void BME280Class::writeFilterCoefficient(filterCoefficient_e fc) {

uint8_t conf;

  conf = readRegister(regConfig);  // Status is hidden in here
  // We want to change osrs_p which is bits 4,3,2
  conf = conf & 0b11100011; // mask out the bits we care about
  conf = conf | (fc << 2); // Set the magic bits

  writeRegister(regConfig, conf);

} 

void BME280Class::writeOversamplingPressure(oversampling_e os) {
 uint8_t ctrlMeas;
  ctrlMeas = readRegister(regCtrlMeas);  // Status is hidden in here
  // We want to change osrs_p which is bits 4,3,2
  ctrlMeas = ctrlMeas & 0b11100011; // mask out the bits we care about
  ctrlMeas = ctrlMeas | (os << 2); // Set the magic bits

  writeRegister(regCtrlMeas, ctrlMeas);

}  

void BME280Class::writeOversamplingTemperature(oversampling_e os) {
 uint8_t ctrlMeas;

  ctrlMeas = readRegister(regCtrlMeas);  // osrs_t is in CtrlMeas
  // We want to change osrs_t which is bits 7,6,5
  ctrlMeas = ctrlMeas & 0b00011111; // mask out the bits we care about
  ctrlMeas = ctrlMeas | (os << 5); // Set the magic bits

  writeRegister(regCtrlMeas, ctrlMeas);

} 

void BME280Class::writeOversamplingHumidity(oversampling_e os) {
 
  // We want to change osrs_h which is bits 2,1,0 - there are no other bits though, so we can just se it.

  writeRegister(regCtrlHum, os);

}

void BME280Class::readCompensationParams(void) {
  
  uint8_t count;
  uint16_t regE5, regE6;
  
  Wire.beginTransmission(addrBME280);
  Wire.write(regCalibStart);
  Wire.endTransmission();
  Wire.requestFrom(addrBME280, 24); 
  for (count = 0; count < 28; count++) {  // first 28 bytes we can process like this
   compParams.compArray[count] = Wire.read();
  }
  // then they go a bit strangely

  compParams.compStruct.dig_H1 = readRegister(0xA1);

  Wire.beginTransmission(addrBME280);
  Wire.write(regCalibStart2);
  Wire.endTransmission();
  Wire.requestFrom(addrBME280, 7);

  compParams.compStruct.dig_H2 = Wire.read();
  compParams.compStruct.dig_H2 |= (uint16_t)Wire.read() << 8;
  compParams.compStruct.dig_H3 = Wire.read();
  compParams.compStruct.dig_H4 = (uint16_t)Wire.read() << 4; // bits 11:4
  regE5 = Wire.read();
  compParams.compStruct.dig_H4 |= regE5 & 0b00001111; // bits 11:4
  compParams.compStruct.dig_H5 = regE5 >> 4;
  regE6 = Wire.read();
  compParams.compStruct.dig_H5 |= regE6 << 4;
  compParams.compStruct.dig_H6 = Wire.read();
  
 
}  

uint8_t BME280Class::readRegister(uint8_t reg) {

  uint8_t result;

  Wire.beginTransmission(addrBME280);
  Wire.write(reg);
  Wire.endTransmission();
  Wire.requestFrom(addrBME280, 1); 
  result = Wire.read();

  return result;
}

void BME280Class::writeRegister(uint8_t reg, uint8_t data) {

  Wire.beginTransmission(addrBME280);
  Wire.write(reg);
  Wire.write(data);
  Wire.endTransmission();
}    

void BME280Class::readMeasurements(void) {

  uint8_t data[8];
  uint8_t count;

  Wire.beginTransmission(addrBME280);
  Wire.write(regMeasurementsStart);
  Wire.endTransmission();
  Wire.requestFrom(addrBME280, 8); 
  for (count = 0; count < 8; count++) {
    data[count] = Wire.read();
  }
  adc_h = data[hum_lsb];
  adc_h |= (uint32_t)data[hum_msb] << 8;
  
  adc_t  = (uint32_t)data[temp_xlsb] >> 4;
  adc_t |= (uint32_t)data[temp_lsb] << 4;
  adc_t |= (uint32_t)data[temp_msb] << 12;
    
  adc_p  = (uint32_t)data[press_xlsb] >> 4;
  adc_p |= (uint32_t)data[press_lsb] << 4;
  adc_p |= (uint32_t)data[press_msb] << 12;
}


void BME280Class::writeMode(mode_e m) {

  uint8_t ctrlMeas;

  ctrlMeas = readRegister(regCtrlMeas);  // Status is hidden in here
  // We want to change mode to 01
  ctrlMeas = ctrlMeas & 0b11111100; // mask out the bits we care about
  ctrlMeas = ctrlMeas | m; // Set the magic bits

  writeRegister(regCtrlMeas, ctrlMeas);

}  

uint8_t  BME280Class::readChipId(void) {
  return readRegister(regChipID);  // Status is hidden in here
}    

uint8_t BME280Class::readCtrlMeas(void) {
   return readRegister(regCtrlMeas);  // Status is hidden in here
}
uint8_t BME280Class::isMeasuring(void) {

  if (readRegister(regStatus) & 0b00001000) {  // Measuring is hidden in here
    return 1;
  } 
  else {
    return 0;
  }
}

uint8_t BME280Class::doingIMUpdate(void) {

  if (readRegister(regStatus) & 0b00000001) {  // Measuring is hidden in here
    return 1;
  } 
  else {
    return 0;
  }
}

BME280Class BME280;