398 lines
11 KiB
C++
398 lines
11 KiB
C++
/*!
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* @file Adafruit_BMP280.cpp
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*
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* This is a library for the BMP280 orientation sensor
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*
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* Designed specifically to work with the Adafruit BMP280 Sensor.
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*
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* Pick one up today in the adafruit shop!
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* ------> https://www.adafruit.com/product/2651
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*
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* These sensors use I2C to communicate, 2 pins are required to interface.
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*
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* Adafruit invests time and resources providing this open source code,
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* please support Adafruit andopen-source hardware by purchasing products
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* from Adafruit!
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*
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* K.Townsend (Adafruit Industries)
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*
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* BSD license, all text above must be included in any redistribution
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*/
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#include "Adafruit_BMP280.h"
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#include "Arduino.h"
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#include <Wire.h>
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/*!
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* @brief BMP280 constructor using i2c
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* @param *theWire
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* optional wire
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*/
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Adafruit_BMP280::Adafruit_BMP280(TwoWire *theWire)
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: _cs(-1), _mosi(-1), _miso(-1), _sck(-1) {
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_wire = theWire;
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}
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/*!
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* @brief BMP280 constructor using hardware SPI
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* @param cspin
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* cs pin number
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* @param theSPI
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* optional SPI object
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*/
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Adafruit_BMP280::Adafruit_BMP280(int8_t cspin, SPIClass *theSPI)
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: _cs(cspin), _mosi(-1), _miso(-1), _sck(-1) {
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*_spi = *theSPI;
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}
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/*!
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* @brief BMP280 constructor using bitbang SPI
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* @param cspin
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* The pin to use for CS/SSEL.
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* @param mosipin
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* The pin to use for MOSI.
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* @param misopin
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* The pin to use for MISO.
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* @param sckpin
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* The pin to use for SCK.
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*/
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Adafruit_BMP280::Adafruit_BMP280(int8_t cspin, int8_t mosipin, int8_t misopin,
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int8_t sckpin)
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: _cs(cspin), _mosi(mosipin), _miso(misopin), _sck(sckpin) {}
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/*!
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* Initialises the sensor.
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* @param addr
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* The I2C address to use (default = 0x77)
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* @param chipid
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* The expected chip ID (used to validate connection).
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* @return True if the init was successful, otherwise false.
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*/
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bool Adafruit_BMP280::begin(uint8_t addr, uint8_t chipid) {
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_i2caddr = addr;
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if (_cs == -1) {
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// i2c
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_wire->begin();
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} else {
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digitalWrite(_cs, HIGH);
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pinMode(_cs, OUTPUT);
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if (_sck == -1) {
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// hardware SPI
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_spi->begin();
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} else {
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// software SPI
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pinMode(_sck, OUTPUT);
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pinMode(_mosi, OUTPUT);
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pinMode(_miso, INPUT);
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}
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}
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if (read8(BMP280_REGISTER_CHIPID) != chipid)
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return false;
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readCoefficients();
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// write8(BMP280_REGISTER_CONTROL, 0x3F); /* needed? */
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setSampling();
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delay(100);
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return true;
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}
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/*!
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* Sets the sampling config for the device.
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* @param mode
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* The operating mode of the sensor.
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* @param tempSampling
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* The sampling scheme for temp readings.
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* @param pressSampling
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* The sampling scheme for pressure readings.
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* @param filter
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* The filtering mode to apply (if any).
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* @param duration
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* The sampling duration.
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*/
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void Adafruit_BMP280::setSampling(sensor_mode mode,
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sensor_sampling tempSampling,
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sensor_sampling pressSampling,
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sensor_filter filter,
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standby_duration duration) {
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_measReg.mode = mode;
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_measReg.osrs_t = tempSampling;
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_measReg.osrs_p = pressSampling;
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_configReg.filter = filter;
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_configReg.t_sb = duration;
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write8(BMP280_REGISTER_CONFIG, _configReg.get());
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write8(BMP280_REGISTER_CONTROL, _measReg.get());
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}
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uint8_t Adafruit_BMP280::spixfer(uint8_t x) {
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if (_sck == -1)
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return SPI.transfer(x);
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// software spi
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// Serial.println("Software SPI");
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uint8_t reply = 0;
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for (int i = 7; i >= 0; i--) {
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reply <<= 1;
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digitalWrite(_sck, LOW);
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digitalWrite(_mosi, x & (1 << i));
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digitalWrite(_sck, HIGH);
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if (digitalRead(_miso))
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reply |= 1;
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}
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return reply;
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}
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/**************************************************************************/
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/*!
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@brief Writes an 8 bit value over I2C/SPI
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*/
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/**************************************************************************/
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void Adafruit_BMP280::write8(byte reg, byte value) {
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if (_cs == -1) {
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_wire->beginTransmission((uint8_t)_i2caddr);
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_wire->write((uint8_t)reg);
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_wire->write((uint8_t)value);
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_wire->endTransmission();
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} else {
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if (_sck == -1)
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_spi->beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
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digitalWrite(_cs, LOW);
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spixfer(reg & ~0x80); // write, bit 7 low
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spixfer(value);
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digitalWrite(_cs, HIGH);
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if (_sck == -1)
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_spi->endTransaction(); // release the SPI bus
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}
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}
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/*!
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* @brief Reads an 8 bit value over I2C/SPI
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* @param reg
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* selected register
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* @return value from selected register
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*/
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uint8_t Adafruit_BMP280::read8(byte reg) {
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uint8_t value;
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if (_cs == -1) {
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_wire->beginTransmission((uint8_t)_i2caddr);
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_wire->write((uint8_t)reg);
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_wire->endTransmission();
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_wire->requestFrom((uint8_t)_i2caddr, (byte)1);
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value = _wire->read();
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} else {
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if (_sck == -1)
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_spi->beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
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digitalWrite(_cs, LOW);
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spixfer(reg | 0x80); // read, bit 7 high
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value = spixfer(0);
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digitalWrite(_cs, HIGH);
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if (_sck == -1)
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_spi->endTransaction(); // release the SPI bus
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}
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return value;
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}
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/*!
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* @brief Reads a 16 bit value over I2C/SPI
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*/
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uint16_t Adafruit_BMP280::read16(byte reg) {
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uint16_t value;
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if (_cs == -1) {
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_wire->beginTransmission((uint8_t)_i2caddr);
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_wire->write((uint8_t)reg);
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_wire->endTransmission();
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_wire->requestFrom((uint8_t)_i2caddr, (byte)2);
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value = (_wire->read() << 8) | _wire->read();
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} else {
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if (_sck == -1)
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_spi->beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
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digitalWrite(_cs, LOW);
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spixfer(reg | 0x80); // read, bit 7 high
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value = (spixfer(0) << 8) | spixfer(0);
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digitalWrite(_cs, HIGH);
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if (_sck == -1)
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_spi->endTransaction(); // release the SPI bus
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}
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return value;
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}
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uint16_t Adafruit_BMP280::read16_LE(byte reg) {
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uint16_t temp = read16(reg);
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return (temp >> 8) | (temp << 8);
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}
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/*!
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* @brief Reads a signed 16 bit value over I2C/SPI
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*/
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int16_t Adafruit_BMP280::readS16(byte reg) { return (int16_t)read16(reg); }
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int16_t Adafruit_BMP280::readS16_LE(byte reg) {
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return (int16_t)read16_LE(reg);
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}
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/*!
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* @brief Reads a 24 bit value over I2C/SPI
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*/
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uint32_t Adafruit_BMP280::read24(byte reg) {
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uint32_t value;
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if (_cs == -1) {
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_wire->beginTransmission((uint8_t)_i2caddr);
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_wire->write((uint8_t)reg);
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_wire->endTransmission();
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_wire->requestFrom((uint8_t)_i2caddr, (byte)3);
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value = _wire->read();
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value <<= 8;
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value |= _wire->read();
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value <<= 8;
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value |= _wire->read();
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} else {
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if (_sck == -1)
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_spi->beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
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digitalWrite(_cs, LOW);
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spixfer(reg | 0x80); // read, bit 7 high
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value = spixfer(0);
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value <<= 8;
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value |= spixfer(0);
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value <<= 8;
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value |= spixfer(0);
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digitalWrite(_cs, HIGH);
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if (_sck == -1)
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_spi->endTransaction(); // release the SPI bus
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}
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return value;
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}
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/*!
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* @brief Reads the factory-set coefficients
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*/
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void Adafruit_BMP280::readCoefficients() {
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_bmp280_calib.dig_T1 = read16_LE(BMP280_REGISTER_DIG_T1);
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_bmp280_calib.dig_T2 = readS16_LE(BMP280_REGISTER_DIG_T2);
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_bmp280_calib.dig_T3 = readS16_LE(BMP280_REGISTER_DIG_T3);
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_bmp280_calib.dig_P1 = read16_LE(BMP280_REGISTER_DIG_P1);
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_bmp280_calib.dig_P2 = readS16_LE(BMP280_REGISTER_DIG_P2);
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_bmp280_calib.dig_P3 = readS16_LE(BMP280_REGISTER_DIG_P3);
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_bmp280_calib.dig_P4 = readS16_LE(BMP280_REGISTER_DIG_P4);
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_bmp280_calib.dig_P5 = readS16_LE(BMP280_REGISTER_DIG_P5);
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_bmp280_calib.dig_P6 = readS16_LE(BMP280_REGISTER_DIG_P6);
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_bmp280_calib.dig_P7 = readS16_LE(BMP280_REGISTER_DIG_P7);
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_bmp280_calib.dig_P8 = readS16_LE(BMP280_REGISTER_DIG_P8);
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_bmp280_calib.dig_P9 = readS16_LE(BMP280_REGISTER_DIG_P9);
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}
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/*!
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* Reads the temperature from the device.
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* @return The temperature in degress celcius.
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*/
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float Adafruit_BMP280::readTemperature() {
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int32_t var1, var2;
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int32_t adc_T = read24(BMP280_REGISTER_TEMPDATA);
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adc_T >>= 4;
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var1 = ((((adc_T >> 3) - ((int32_t)_bmp280_calib.dig_T1 << 1))) *
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((int32_t)_bmp280_calib.dig_T2)) >>
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11;
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var2 = (((((adc_T >> 4) - ((int32_t)_bmp280_calib.dig_T1)) *
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((adc_T >> 4) - ((int32_t)_bmp280_calib.dig_T1))) >>
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12) *
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((int32_t)_bmp280_calib.dig_T3)) >>
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14;
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t_fine = var1 + var2;
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float T = (t_fine * 5 + 128) >> 8;
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return T / 100;
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}
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/*!
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* Reads the barometric pressure from the device.
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* @return Barometric pressure in hPa.
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*/
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float Adafruit_BMP280::readPressure() {
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int64_t var1, var2, p;
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// Must be done first to get the t_fine variable set up
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readTemperature();
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int32_t adc_P = read24(BMP280_REGISTER_PRESSUREDATA);
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adc_P >>= 4;
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var1 = ((int64_t)t_fine) - 128000;
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var2 = var1 * var1 * (int64_t)_bmp280_calib.dig_P6;
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var2 = var2 + ((var1 * (int64_t)_bmp280_calib.dig_P5) << 17);
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var2 = var2 + (((int64_t)_bmp280_calib.dig_P4) << 35);
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var1 = ((var1 * var1 * (int64_t)_bmp280_calib.dig_P3) >> 8) +
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((var1 * (int64_t)_bmp280_calib.dig_P2) << 12);
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var1 =
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(((((int64_t)1) << 47) + var1)) * ((int64_t)_bmp280_calib.dig_P1) >> 33;
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if (var1 == 0) {
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return 0; // avoid exception caused by division by zero
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}
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p = 1048576 - adc_P;
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p = (((p << 31) - var2) * 3125) / var1;
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var1 = (((int64_t)_bmp280_calib.dig_P9) * (p >> 13) * (p >> 13)) >> 25;
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var2 = (((int64_t)_bmp280_calib.dig_P8) * p) >> 19;
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p = ((p + var1 + var2) >> 8) + (((int64_t)_bmp280_calib.dig_P7) << 4);
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return (float)p / 256;
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}
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/*!
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* @brief Calculates the approximate altitude using barometric pressure and the
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* supplied sea level hPa as a reference.
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* @param seaLevelhPa
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* The current hPa at sea level.
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* @return The approximate altitude above sea level in meters.
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*/
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float Adafruit_BMP280::readAltitude(float seaLevelhPa) {
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float altitude;
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float pressure = readPressure(); // in Si units for Pascal
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pressure /= 100;
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altitude = 44330 * (1.0 - pow(pressure / seaLevelhPa, 0.1903));
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return altitude;
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}
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/*!
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* @brief Take a new measurement (only possible in forced mode)
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* !!!todo!!!
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*/
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/*
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void Adafruit_BMP280::takeForcedMeasurement()
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{
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// If we are in forced mode, the BME sensor goes back to sleep after each
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// measurement and we need to set it to forced mode once at this point, so
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// it will take the next measurement and then return to sleep again.
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// In normal mode simply does new measurements periodically.
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if (_measReg.mode == MODE_FORCED) {
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// set to forced mode, i.e. "take next measurement"
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write8(BMP280_REGISTER_CONTROL, _measReg.get());
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// wait until measurement has been completed, otherwise we would read
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// the values from the last measurement
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while (read8(BMP280_REGISTER_STATUS) & 0x08)
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delay(1);
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}
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}
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*/
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