src/lib/Baro/baro_bmp280.cpp

   1 #include "baro_bmp280.h"
   2 #include <Arduino.h>
   3 #include "logging.h"
   4
   5 void BMP280::initialize()
   6 {
   7     if (m_initialized)
   8         return;
   9
  10     // All the calibration registers are in order of our struct and are 2 bytes long too,
  11     // so just read them directly into our calib data
  12     readRegister(BMP280_REG_CALIB_COEFFS_START, (uint8_t *)&m_calib, sizeof(m_calib));
  13
  14     // configure IIR filter, 0.5ms standby time (freerunning)
  15     constexpr uint8_t BMP280_FILTER = FILTER_COEFF << 2;
  16     writeRegister(BMP280_REG_CONFIG, (uint8_t *)&BMP280_FILTER, sizeof(BMP280_FILTER));
  17
  18     m_initialized = true;
  19 }
  20
  21 uint8_t BMP280::getTemperatureDuration()
  22 {
  23     // Calculate in microseconds, then divide by 1000 for ms, rounding up
  24     constexpr uint32_t duration = 1250U +
  25         (2300U * ((1U << OVERSAMPLING_TEMPERATURE) >> 1)) +
  26         (2300U * ((1U << OVERSAMPLING_PRESSURE) >> 1) + 575U);
  27     return (FREERUNNING_NUM_SAMPLES * duration + 999U) / 1000U;
  28 }
  29
  30 void BMP280::startTemperature()
  31 {
  32     // Measure both Pressure and Temperature, freerunning to allow internal IIR to smooth extra samples for us
  33     constexpr uint8_t SAMPLING_MODE = (FREERUNNING_NUM_SAMPLES != 0) ? BMP280_MODE_NORMAL : BMP280_MODE_FORCED;
  34     constexpr uint8_t BMP280_MODE = (OVERSAMPLING_PRESSURE << 2 | OVERSAMPLING_TEMPERATURE << 5 | SAMPLING_MODE);
  35     writeRegister(BMP280_REG_CTRL_MEAS, (uint8_t *)&BMP280_MODE, sizeof(BMP280_MODE));
  36 }
  37
  38 uint32_t BMP280::getPressure()
  39 {
  40     return m_pressureLast;
  41 }
  42
  43 int32_t BMP280::getTemperature()
  44 {
  45     // uint8_t status = 0xff;
  46     // readRegister(BMP280_REG_STATUS, &status, sizeof(status));
  47     // if (status & bit(3))
  48     // {
  49     //     DBGLN("not ready");
  50     // }
  51
  52     uint8_t buf[BMP280_LEN_TEMP_PRESS_DATA] = {0};
  53     readRegister(BMP280_REG_PRESSURE_MSB, buf, sizeof(buf));
  54
  55     int32_t adc_P = ((uint32_t)buf[0] << 12) | ((uint32_t)buf[1] << 4) | ((uint32_t)buf[2] >> 4);
  56     int32_t adc_T = ((uint32_t)buf[3] << 12) | ((uint32_t)buf[4] << 4) | ((uint32_t)buf[5] >> 4);
  57
  58     // BME280_compensate_T_int32()
  59     int32_t var01, var02;
  60     var01 = ((((adc_T >> 3) - ((int32_t)m_calib.dig_T1 << 1))) * ((int32_t)m_calib.dig_T2)) >> 11;
  61     var02  = (((((adc_T >> 4) - ((int32_t)m_calib.dig_T1)) * ((adc_T >> 4) - ((int32_t)m_calib.dig_T1))) >> 12) * ((int32_t)m_calib.dig_T3)) >> 14;
  62     int32_t t_fine = var01 + var02;
  63
  64     // BME280_compensate_P_int64()
  65     int64_t var1, var2, p;
  66     var1 = ((int64_t)t_fine) - 128000;
  67     var2 = var1 * var1 * (int64_t)m_calib.dig_P6;
  68     var2 = var2 + ((var1*(int64_t)m_calib.dig_P5) << 17);
  69     var2 = var2 + (((int64_t)m_calib.dig_P4) << 35);
  70     var1 = ((var1 * var1 * (int64_t)m_calib.dig_P3) >> 8) + ((var1 * (int64_t)m_calib.dig_P2) << 12);
  71     var1 = (((((int64_t)1) << 47) + var1)) * ((int64_t)m_calib.dig_P1) >> 33;
  72     if (var1 == 0)
  73         return BaroBase::PRESSURE_INVALID;
  74
  75     p = 1048576 - adc_P;
  76     p = (((p << 31) - var2) * 3125) / var1;
  77     var1 = (((int64_t)m_calib.dig_P9) * (p >> 13) * (p >> 13)) >> 25;
  78     var2 = (((int64_t)m_calib.dig_P8) * p) >> 19;
  79     p = ((p + var1 + var2) >> 8) + (((int64_t)m_calib.dig_P7) << 4);
  80     // p is pressure in Pa as unsigned 32 bit integer in Q24.8 format (24 integer bits and 8 fractional bits).
  81     // Output value of "24674867" represents 24674867/256 = 96386.2 Pa = 963.862 hPa
  82     m_pressureLast = ((uint32_t)p) >> 8;
  83
  84     int32_t temperature = (t_fine * 5 + 128) >> 8;
  85     //DBGLN("%u t=%d p=%u", millis(), temperature, m_pressureLast);
  86
  87     return temperature;
  88 }
  89
  90 bool BMP280::detect()
  91 {
  92     // Assumes Wire.begin() has already been called
  93     uint8_t chipid = 0;
  94
  95     // BMP280 can have two addresses based on the SDO pin.
  96     // Adafruit breakout has it tied high, Aliexpress boards have it tied low
  97     for (uint8_t addr : { BMP280_I2C_ADDR, BMP280_I2C_ADDR_ALT })
  98     {
  99        m_address = addr;
 100        readRegister(BMP280_REG_CHIPID, &chipid, sizeof(chipid));
 101        if (chipid == BMP280_CHIPID || chipid == BME280_CHIPID)
 102            return true;
 103     }
 104
 105     return false;
 106 }