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/*!
* @file Adafruit_BME280.cpp
*
* @mainpage Adafruit BME280 humidity, temperature & pressure sensor
*
* @section intro_sec Introduction
*
* Driver for the BME280 humidity, temperature & pressure sensor
*
* These sensors use I2C or SPI to communicate, 2 or 4 pins are required
* to interface.
*
* Designed specifically to work with the Adafruit BME280 Breakout
* ----> http://www.adafruit.com/products/2652
*
* Adafruit invests time and resources providing this open source code,
* please support Adafruit and open-source hardware by purchasing
* products from Adafruit!
*
* @section author Author
*
* Written by Kevin "KTOWN" Townsend for Adafruit Industries.
*
* @section license License
*
* BSD license, all text here must be included in any redistribution.
* See the LICENSE file for details.
*
*/
#include "Adafruit_BME280.h"
#include "Arduino.h"
#include <SPI.h>
#include <Wire.h>
/*!
* @brief class constructor
*/
Adafruit_BME280::Adafruit_BME280() : _cs(-1), _mosi(-1), _miso(-1), _sck(-1) {}
/*!
* @brief class constructor if using hardware SPI
* @param cspin the chip select pin to use
* @param *theSPI
* optional SPI object
*/
Adafruit_BME280::Adafruit_BME280(int8_t cspin, SPIClass *theSPI) {
_cs = cspin;
_mosi = _miso = _sck = -1;
_spi = theSPI;
}
/*!
* @brief class constructor if using software SPI
* @param cspin the chip select pin to use
* @param mosipin the MOSI pin to use
* @param misopin the MISO pin to use
* @param sckpin the SCK pin to use
*/
Adafruit_BME280::Adafruit_BME280(int8_t cspin, int8_t mosipin, int8_t misopin,
int8_t sckpin)
: _cs(cspin), _mosi(mosipin), _miso(misopin), _sck(sckpin) {}
/*!
* @brief Initialise sensor with given parameters / settings
* @param addr the I2C address the device can be found on
* @param theWire the I2C object to use
* @returns true on success, false otherwise
*/
bool Adafruit_BME280::begin(uint8_t addr, TwoWire *theWire) {
bool status = false;
_i2caddr = addr;
_wire = theWire;
status = init();
if ((!status) && (addr != BME280_ADDRESS)) {
_i2caddr = BME280_ADDRESS;
status = init();
}
if ((!status) && (addr != BME280_ADDRESS_ALTERNATE)) {
_i2caddr = BME280_ADDRESS_ALTERNATE;
status = init();
}
return status;
}
/*!
* @brief Initialise sensor with given parameters / settings
* @param theWire the I2C object to use
* @returns true on success, false otherwise
*/
bool Adafruit_BME280::begin(TwoWire *theWire) {
return begin(BME280_ADDRESS, theWire);
}
/*!
* @brief Initialise sensor with given parameters / settings
* @param addr the I2C address the device can be found on
* @returns true on success, false otherwise
*/
bool Adafruit_BME280::begin(uint8_t addr) {
return begin(addr, &Wire);
}
/*!
* @brief Initialise sensor with given parameters / settings
* @returns true on success, false otherwise
*/
bool Adafruit_BME280::begin(void) {
return begin(BME280_ADDRESS, &Wire);
}
/*!
* @brief Initialise sensor with given parameters / settings
* @returns true on success, false otherwise
*/
bool Adafruit_BME280::init() {
// init I2C or SPI sensor interface
if (_cs == -1) {
// I2C
_wire->begin();
} else {
digitalWrite(_cs, HIGH);
pinMode(_cs, OUTPUT);
if (_sck == -1) {
// hardware SPI
_spi->begin();
} else {
// software SPI
pinMode(_sck, OUTPUT);
pinMode(_mosi, OUTPUT);
pinMode(_miso, INPUT);
}
}
// check if sensor, i.e. the chip ID is correct
_sensorID = read8(BME280_REGISTER_CHIPID);
if (_sensorID != 0x60)
return false;
// reset the device using soft-reset
// this makes sure the IIR is off, etc.
write8(BME280_REGISTER_SOFTRESET, 0xB6);
// wait for chip to wake up.
delay(300);
// if chip is still reading calibration, delay
while (isReadingCalibration())
delay(100);
readCoefficients(); // read trimming parameters, see DS 4.2.2
setSampling(); // use defaults
delay(100);
return true;
}
/*!
* @brief setup sensor with given parameters / settings
*
* This is simply a overload to the normal begin()-function, so SPI users
* don't get confused about the library requiring an address.
* @param mode the power mode to use for the sensor
* @param tempSampling the temp samping rate to use
* @param pressSampling the pressure sampling rate to use
* @param humSampling the humidity sampling rate to use
* @param filter the filter mode to use
* @param duration the standby duration to use
*/
void Adafruit_BME280::setSampling(sensor_mode mode,
sensor_sampling tempSampling,
sensor_sampling pressSampling,
sensor_sampling humSampling,
sensor_filter filter,
standby_duration duration) {
_measReg.mode = mode;
_measReg.osrs_t = tempSampling;
_measReg.osrs_p = pressSampling;
_humReg.osrs_h = humSampling;
_configReg.filter = filter;
_configReg.t_sb = duration;
// making sure sensor is in sleep mode before setting configuration
// as it otherwise may be ignored
write8(BME280_REGISTER_CONTROL, MODE_SLEEP);
// you must make sure to also set REGISTER_CONTROL after setting the
// CONTROLHUMID register, otherwise the values won't be applied (see
// DS 5.4.3)
write8(BME280_REGISTER_CONTROLHUMID, _humReg.get());
write8(BME280_REGISTER_CONFIG, _configReg.get());
write8(BME280_REGISTER_CONTROL, _measReg.get());
}
/*!
* @brief Encapsulate hardware and software SPI transfer into one
* function
* @param x the data byte to transfer
* @returns the data byte read from the device
*/
uint8_t Adafruit_BME280::spixfer(uint8_t x) {
// hardware SPI
if (_sck == -1)
return _spi->transfer(x);
// software SPI
uint8_t reply = 0;
for (int i = 7; i >= 0; i--) {
reply <<= 1;
digitalWrite(_sck, LOW);
digitalWrite(_mosi, x & (1 << i));
digitalWrite(_sck, HIGH);
if (digitalRead(_miso))
reply |= 1;
}
return reply;
}
/*!
* @brief Writes an 8 bit value over I2C or SPI
* @param reg the register address to write to
* @param value the value to write to the register
*/
void Adafruit_BME280::write8(byte reg, byte value) {
if (_cs == -1) {
_wire->beginTransmission((uint8_t)_i2caddr);
_wire->write((uint8_t)reg);
_wire->write((uint8_t)value);
_wire->endTransmission();
} else {
if (_sck == -1)
_spi->beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
digitalWrite(_cs, LOW);
spixfer(reg & ~0x80); // write, bit 7 low
spixfer(value);
digitalWrite(_cs, HIGH);
if (_sck == -1)
_spi->endTransaction(); // release the SPI bus
}
}
/*!
* @brief Reads an 8 bit value over I2C or SPI
* @param reg the register address to read from
* @returns the data byte read from the device
*/
uint8_t Adafruit_BME280::read8(byte reg) {
uint8_t value;
if (_cs == -1) {
_wire->beginTransmission((uint8_t)_i2caddr);
_wire->write((uint8_t)reg);
_wire->endTransmission();
_wire->requestFrom((uint8_t)_i2caddr, (byte)1);
value = _wire->read();
} else {
if (_sck == -1)
_spi->beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
digitalWrite(_cs, LOW);
spixfer(reg | 0x80); // read, bit 7 high
value = spixfer(0);
digitalWrite(_cs, HIGH);
if (_sck == -1)
_spi->endTransaction(); // release the SPI bus
}
return value;
}
/*!
* @brief Reads a 16 bit value over I2C or SPI
* @param reg the register address to read from
* @returns the 16 bit data value read from the device
*/
uint16_t Adafruit_BME280::read16(byte reg) {
uint16_t value;
if (_cs == -1) {
_wire->beginTransmission((uint8_t)_i2caddr);
_wire->write((uint8_t)reg);
_wire->endTransmission();
_wire->requestFrom((uint8_t)_i2caddr, (byte)2);
value = (_wire->read() << 8) | _wire->read();
} else {
if (_sck == -1)
_spi->beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
digitalWrite(_cs, LOW);
spixfer(reg | 0x80); // read, bit 7 high
value = (spixfer(0) << 8) | spixfer(0);
digitalWrite(_cs, HIGH);
if (_sck == -1)
_spi->endTransaction(); // release the SPI bus
}
return value;
}
/*!
* @brief Reads a signed 16 bit little endian value over I2C or SPI
* @param reg the register address to read from
* @returns the 16 bit data value read from the device
*/
uint16_t Adafruit_BME280::read16_LE(byte reg) {
uint16_t temp = read16(reg);
return (temp >> 8) | (temp << 8);
}
/*!
* @brief Reads a signed 16 bit value over I2C or SPI
* @param reg the register address to read from
* @returns the 16 bit data value read from the device
*/
int16_t Adafruit_BME280::readS16(byte reg) { return (int16_t)read16(reg); }
/*!
* @brief Reads a signed little endian 16 bit value over I2C or SPI
* @param reg the register address to read from
* @returns the 16 bit data value read from the device
*/
int16_t Adafruit_BME280::readS16_LE(byte reg) {
return (int16_t)read16_LE(reg);
}
/*!
* @brief Reads a 24 bit value over I2C
* @param reg the register address to read from
* @returns the 24 bit data value read from the device
*/
uint32_t Adafruit_BME280::read24(byte reg) {
uint32_t value;
if (_cs == -1) {
_wire->beginTransmission((uint8_t)_i2caddr);
_wire->write((uint8_t)reg);
_wire->endTransmission();
_wire->requestFrom((uint8_t)_i2caddr, (byte)3);
value = _wire->read();
value <<= 8;
value |= _wire->read();
value <<= 8;
value |= _wire->read();
} else {
if (_sck == -1)
_spi->beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
digitalWrite(_cs, LOW);
spixfer(reg | 0x80); // read, bit 7 high
value = spixfer(0);
value <<= 8;
value |= spixfer(0);
value <<= 8;
value |= spixfer(0);
digitalWrite(_cs, HIGH);
if (_sck == -1)
_spi->endTransaction(); // release the SPI bus
}
return value;
}
/*!
* @brief Take a new measurement (only possible in forced mode)
*/
void Adafruit_BME280::takeForcedMeasurement() {
// If we are in forced mode, the BME sensor goes back to sleep after each
// measurement and we need to set it to forced mode once at this point, so
// it will take the next measurement and then return to sleep again.
// In normal mode simply does new measurements periodically.
if (_measReg.mode == MODE_FORCED) {
// set to forced mode, i.e. "take next measurement"
write8(BME280_REGISTER_CONTROL, _measReg.get());
// wait until measurement has been completed, otherwise we would read
// the values from the last measurement
while (read8(BME280_REGISTER_STATUS) & 0x08)
delay(1);
}
}
/*!
* @brief Reads the factory-set coefficients
*/
void Adafruit_BME280::readCoefficients(void) {
_bme280_calib.dig_T1 = read16_LE(BME280_REGISTER_DIG_T1);
_bme280_calib.dig_T2 = readS16_LE(BME280_REGISTER_DIG_T2);
_bme280_calib.dig_T3 = readS16_LE(BME280_REGISTER_DIG_T3);
_bme280_calib.dig_P1 = read16_LE(BME280_REGISTER_DIG_P1);
_bme280_calib.dig_P2 = readS16_LE(BME280_REGISTER_DIG_P2);
_bme280_calib.dig_P3 = readS16_LE(BME280_REGISTER_DIG_P3);
_bme280_calib.dig_P4 = readS16_LE(BME280_REGISTER_DIG_P4);
_bme280_calib.dig_P5 = readS16_LE(BME280_REGISTER_DIG_P5);
_bme280_calib.dig_P6 = readS16_LE(BME280_REGISTER_DIG_P6);
_bme280_calib.dig_P7 = readS16_LE(BME280_REGISTER_DIG_P7);
_bme280_calib.dig_P8 = readS16_LE(BME280_REGISTER_DIG_P8);
_bme280_calib.dig_P9 = readS16_LE(BME280_REGISTER_DIG_P9);
_bme280_calib.dig_H1 = read8(BME280_REGISTER_DIG_H1);
_bme280_calib.dig_H2 = readS16_LE(BME280_REGISTER_DIG_H2);
_bme280_calib.dig_H3 = read8(BME280_REGISTER_DIG_H3);
_bme280_calib.dig_H4 = (read8(BME280_REGISTER_DIG_H4) << 4) |
(read8(BME280_REGISTER_DIG_H4 + 1) & 0xF);
_bme280_calib.dig_H5 = (read8(BME280_REGISTER_DIG_H5 + 1) << 4) |
(read8(BME280_REGISTER_DIG_H5) >> 4);
_bme280_calib.dig_H6 = (int8_t)read8(BME280_REGISTER_DIG_H6);
}
/*!
* @brief return true if chip is busy reading cal data
* @returns true if reading calibration, false otherwise
*/
bool Adafruit_BME280::isReadingCalibration(void) {
uint8_t const rStatus = read8(BME280_REGISTER_STATUS);
return (rStatus & (1 << 0)) != 0;
}
/*!
* @brief Returns the temperature from the sensor
* @returns the temperature read from the device
*/
float Adafruit_BME280::readTemperature(void) {
int32_t var1, var2;
int32_t adc_T = read24(BME280_REGISTER_TEMPDATA);
if (adc_T == 0x800000) // value in case temp measurement was disabled
return NAN;
adc_T >>= 4;
var1 = ((((adc_T >> 3) - ((int32_t)_bme280_calib.dig_T1 << 1))) *
((int32_t)_bme280_calib.dig_T2)) >>
11;
var2 = (((((adc_T >> 4) - ((int32_t)_bme280_calib.dig_T1)) *
((adc_T >> 4) - ((int32_t)_bme280_calib.dig_T1))) >>
12) *
((int32_t)_bme280_calib.dig_T3)) >>
14;
t_fine = var1 + var2;
float T = (t_fine * 5 + 128) >> 8;
return T / 100;
}
/*!
* @brief Returns the pressure from the sensor
* @returns the pressure value (in Pascal) read from the device
*/
float Adafruit_BME280::readPressure(void) {
int64_t var1, var2, p;
readTemperature(); // must be done first to get t_fine
int32_t adc_P = read24(BME280_REGISTER_PRESSUREDATA);
if (adc_P == 0x800000) // value in case pressure measurement was disabled
return NAN;
adc_P >>= 4;
var1 = ((int64_t)t_fine) - 128000;
var2 = var1 * var1 * (int64_t)_bme280_calib.dig_P6;
var2 = var2 + ((var1 * (int64_t)_bme280_calib.dig_P5) << 17);
var2 = var2 + (((int64_t)_bme280_calib.dig_P4) << 35);
var1 = ((var1 * var1 * (int64_t)_bme280_calib.dig_P3) >> 8) +
((var1 * (int64_t)_bme280_calib.dig_P2) << 12);
var1 =
(((((int64_t)1) << 47) + var1)) * ((int64_t)_bme280_calib.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 = (((int64_t)_bme280_calib.dig_P9) * (p >> 13) * (p >> 13)) >> 25;
var2 = (((int64_t)_bme280_calib.dig_P8) * p) >> 19;
p = ((p + var1 + var2) >> 8) + (((int64_t)_bme280_calib.dig_P7) << 4);
return (float)p / 256;
}
/*!
* @brief Returns the humidity from the sensor
* @returns the humidity value read from the device
*/
float Adafruit_BME280::readHumidity(void) {
readTemperature(); // must be done first to get t_fine
int32_t adc_H = read16(BME280_REGISTER_HUMIDDATA);
if (adc_H == 0x8000) // value in case humidity measurement was disabled
return NAN;
int32_t v_x1_u32r;
v_x1_u32r = (t_fine - ((int32_t)76800));
v_x1_u32r = (((((adc_H << 14) - (((int32_t)_bme280_calib.dig_H4) << 20) -
(((int32_t)_bme280_calib.dig_H5) * v_x1_u32r)) +
((int32_t)16384)) >>
15) *
(((((((v_x1_u32r * ((int32_t)_bme280_calib.dig_H6)) >> 10) *
(((v_x1_u32r * ((int32_t)_bme280_calib.dig_H3)) >> 11) +
((int32_t)32768))) >>
10) +
((int32_t)2097152)) *
((int32_t)_bme280_calib.dig_H2) +
8192) >>
14));
v_x1_u32r = (v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) *
((int32_t)_bme280_calib.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;
float h = (v_x1_u32r >> 12);
return h / 1024.0;
}
/*!
* Calculates the altitude (in meters) from the specified atmospheric
* pressure (in hPa), and sea-level pressure (in hPa).
* @param seaLevel Sea-level pressure in hPa
* @returns the altitude value read from the device
*/
float Adafruit_BME280::readAltitude(float seaLevel) {
// Equation taken from BMP180 datasheet (page 16):
// http://www.adafruit.com/datasheets/BST-BMP180-DS000-09.pdf
// Note that using the equation from wikipedia can give bad results
// at high altitude. See this thread for more information:
// http://forums.adafruit.com/viewtopic.php?f=22&t=58064
float atmospheric = readPressure() / 100.0F;
return 44330.0 * (1.0 - pow(atmospheric / seaLevel, 0.1903));
}
/*!
* Calculates the pressure at sea level (in hPa) from the specified
* altitude (in meters), and atmospheric pressure (in hPa).
* @param altitude Altitude in meters
* @param atmospheric Atmospheric pressure in hPa
* @returns the pressure at sea level (in hPa) from the specified altitude
*/
float Adafruit_BME280::seaLevelForAltitude(float altitude, float atmospheric) {
// Equation taken from BMP180 datasheet (page 17):
// http://www.adafruit.com/datasheets/BST-BMP180-DS000-09.pdf
// Note that using the equation from wikipedia can give bad results
// at high altitude. See this thread for more information:
// http://forums.adafruit.com/viewtopic.php?f=22&t=58064
return atmospheric / pow(1.0 - (altitude / 44330.0), 5.255);
}
/*!
* Returns Sensor ID found by init() for diagnostics
* @returns Sensor ID 0x60 for BME280, 0x56, 0x57, 0x58 BMP280
*/
uint32_t Adafruit_BME280::sensorID(void) { return _sensorID; }
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