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bmp280/bme280: C port, C++ wraps C
Some private methods (relating to calibration/compensation) are no longer exposed. In addition, the driver auto-detects the chip (BMP280 or BME280) and acts accordingly, rather than requiring the specification of a chip id in the ctor. The getHumidity() method no longer accepts an arguement representing pressure at sea level. A new method is provided to specify this. Signed-off-by: Jon Trulson <jtrulson@ics.com>
This commit is contained in:
Jon Trulson
@ -1,6 +1,8 @@
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/*
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* Author: Jon Trulson <jtrulson@ics.com>
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* Copyright (c) 2016 Intel Corporation.
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* Copyright (c) 2016-2017 Intel Corporation.
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*
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* The MIT License
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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@ -34,141 +36,23 @@
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using namespace upm;
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using namespace std;
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BME280::BME280(int bus, int addr, int cs, uint8_t theChipID) :
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BMP280(bus, addr, cs, theChipID)
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BME280::BME280(int bus, int addr, int cs) :
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BMP280(bus, addr, cs)
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{
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m_humidity = 0;
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m_dig_H1 = 0;
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m_dig_H2 = 0;
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m_dig_H3 = 0;
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m_dig_H4 = 0;
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m_dig_H5 = 0;
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m_dig_H6 = 0;
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// set sleep mode for now
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setMeasureMode(MODE_SLEEP);
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// read calibration data
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readCalibrationData();
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// set the default mode to the highest resolution mode
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setUsageMode(USAGE_MODE_INDOOR_NAV);
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}
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BME280::~BME280()
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{
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}
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void BME280::update()
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{
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// call the base class method first. This will handle the details
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// WRT forced mode so that we can always be sure to read valid data
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// regardless of the underlying measurement mode.
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BMP280::update();
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int32_t hum = 0;
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const int dataLen = 2;
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uint8_t data[dataLen];
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memset(data, 0, dataLen);
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int rv;
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if ((rv = readRegs(REG_HUMIDITY_MSB, data, dataLen)) != dataLen)
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{
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throw std::runtime_error(std::string(__FUNCTION__)
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+ ": readRegs() failed, returned "
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+ std::to_string(rv));
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}
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// 20 bits unsigned stored in a 32bit signed quanty
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hum = ( (data[0] << 8) | data[1] );
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m_humidity = float(bme280_compensate_H_int32(hum));
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m_humidity /= 1024.0;
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}
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void BME280::readCalibrationData()
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{
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m_dig_H1 = readReg(REG_CALIB_DIG_H1);
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const int calibLen = 7;
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uint8_t calibData[calibLen];
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readRegs(REG_CALIB_DIG_H2_LSB, calibData, calibLen);
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m_dig_H2 = int16_t((calibData[1] << 8) | calibData[0]);
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m_dig_H3 = calibData[2];
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m_dig_H4 = int16_t( (calibData[3] << 4) |
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(calibData[4] & 0x0f) );
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m_dig_H5 = int16_t( ((calibData[4] & 0xf0) >> 4) |
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(calibData[5] << 4) );
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m_dig_H6 = int8_t(calibData[6]);
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# if 0
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cerr << std::dec
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<< "H1: " << (int)m_dig_H1
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<< " H2: " << (int)m_dig_H2
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<< " H3: " << (int)m_dig_H3
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<< " H4: " << (int)m_dig_H4
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<< " H5: " << (int)m_dig_H5
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<< " H6: " << (int)m_dig_H5
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<< endl;
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# endif // 0
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// The BMP280 ctor will call it's version of readCalibrationData
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}
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float BME280::getHumidity()
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{
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return m_humidity;
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return bmp280_get_humidity(m_bmp280);
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}
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void BME280::setOversampleRateHumidity(OSRS_H_T rate)
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void BME280::setOversampleRateHumidity(BME280_OSRS_H_T rate)
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{
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uint8_t reg = readReg(REG_CTRL_HUM);
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reg &= ~(_CTRL_HUM_OSRS_H_MASK << _CTRL_HUM_OSRS_H_SHIFT);
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reg |= (rate << _CTRL_HUM_OSRS_H_SHIFT);
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writeReg(REG_CTRL_HUM, reg);
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bmp280_set_oversample_rate_humidity(m_bmp280, rate);
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}
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void BME280::setUsageMode(USAGE_MODE_T mode)
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{
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// Here, we just set the default humidity oversample to 1 and then
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// call the base method.
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m_humidity = 0;
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// set sleep mode first
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setMeasureMode(MODE_SLEEP);
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setOversampleRateHumidity(OSRS_H_OVERSAMPLING_1);
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BMP280::setUsageMode(mode);
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}
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// This function comes from the BMP180 datasheet, section 4.2.3
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// Returns humidity in %RH as unsigned 32 bit integer in Q22.10 format
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// (22 integer and 10 fractional bits). Output value of “47445”
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// represents 47445/1024 = 46.333 %RH
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uint32_t BME280::bme280_compensate_H_int32(int32_t adc_H)
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{
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int32_t v_x1_u32r;
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v_x1_u32r = (m_t_fine - ((int32_t)76800));
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v_x1_u32r = (((((adc_H << 14) - (((int32_t)m_dig_H4) << 20) - (((int32_t)m_dig_H5) * v_x1_u32r)) +
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((int32_t)16384)) >> 15) * (((((((v_x1_u32r * ((int32_t)m_dig_H6)) >> 10) * (((v_x1_u32r * ((int32_t)m_dig_H3)) >> 11) + ((int32_t)32768))) >> 10) + ((int32_t)2097152)) * ((int32_t)m_dig_H2) + 8192) >> 14));
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v_x1_u32r = (v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) * ((int32_t)m_dig_H1)) >> 4));
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v_x1_u32r = (v_x1_u32r < 0 ? 0 : v_x1_u32r);
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v_x1_u32r = (v_x1_u32r > 419430400 ? 419430400 : v_x1_u32r);
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return (int32_t)(v_x1_u32r>>12);
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}
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