325 lines
8.9 KiB
C++
325 lines
8.9 KiB
C++
/***************************************************************************
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This is a library for the BMP280 pressure sensor
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Designed specifically to work with the Adafruit BMP280 Breakout
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----> http://www.adafruit.com/products/2651
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These sensors use I2C to communicate, 2 pins are required to interface.
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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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Written by Kevin Townsend for Adafruit Industries.
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BSD license, all text above must be included in any redistribution
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***************************************************************************/
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#include "Arduino.h"
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#include <Wire.h>
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#include <SPI.h>
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#include "Adafruit_BMP280.h"
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/***************************************************************************
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PRIVATE FUNCTIONS
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***************************************************************************/
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Adafruit_BMP280::Adafruit_BMP280()
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: _cs(-1), _mosi(-1), _miso(-1), _sck(-1)
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{ }
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Adafruit_BMP280::Adafruit_BMP280(int8_t cspin)
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: _cs(cspin), _mosi(-1), _miso(-1), _sck(-1)
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{ }
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Adafruit_BMP280::Adafruit_BMP280(int8_t cspin, int8_t mosipin, int8_t misopin, int8_t sckpin)
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: _cs(cspin), _mosi(mosipin), _miso(misopin), _sck(sckpin)
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{ }
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bool Adafruit_BMP280::begin(uint8_t a, uint8_t chipid) {
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_i2caddr = a;
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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);
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return true;
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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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{
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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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/*!
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@brief Reads an 8 bit value over I2C/SPI
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*/
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/**************************************************************************/
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uint8_t Adafruit_BMP280::read8(byte reg)
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{
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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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/*!
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@brief Reads a 16 bit value over I2C/SPI
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*/
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/**************************************************************************/
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uint16_t Adafruit_BMP280::read16(byte reg)
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{
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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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/*!
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@brief Reads a signed 16 bit value over I2C/SPI
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*/
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/**************************************************************************/
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int16_t Adafruit_BMP280::readS16(byte reg)
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{
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return (int16_t)read16(reg);
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}
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int16_t Adafruit_BMP280::readS16_LE(byte reg)
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{
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return (int16_t)read16_LE(reg);
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}
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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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/**************************************************************************/
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uint32_t Adafruit_BMP280::read24(byte reg)
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{
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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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/*!
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@brief Reads the factory-set coefficients
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*/
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/**************************************************************************/
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void Adafruit_BMP280::readCoefficients(void)
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{
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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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/*!
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*/
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/**************************************************************************/
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float Adafruit_BMP280::readTemperature(void)
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{
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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)) >> 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))) >> 12) *
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((int32_t)_bmp280_calib.dig_T3)) >> 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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/*!
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*/
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/**************************************************************************/
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float Adafruit_BMP280::readPressure(void) {
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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 = (((((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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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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