[175] | 1 | /***************************************************************************
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| 2 | This is a library for the BME280 humidity, temperature & pressure sensor
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| 3 |
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| 4 | Designed specifically to work with the Adafruit BME280 Breakout
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| 5 | ----> http://www.adafruit.com/products/2650
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| 6 |
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| 7 | These sensors use I2C or SPI to communicate, 2 or 4 pins are required
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| 8 | to interface.
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| 9 |
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| 10 | Adafruit invests time and resources providing this open source code,
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| 11 | please support Adafruit andopen-source hardware by purchasing products
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| 12 | from Adafruit!
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| 13 |
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| 14 | Written by Limor Fried & Kevin Townsend for Adafruit Industries.
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| 15 | BSD license, all text above must be included in any redistribution
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| 16 | ***************************************************************************/
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| 17 | #include "Arduino.h"
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| 18 | #include <Wire.h>
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| 19 | #include "BME280.h"
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| 20 |
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| 21 |
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| 22 | /***************************************************************************
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| 23 | PRIVATE FUNCTIONS
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| 24 | ***************************************************************************/
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| 25 |
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| 26 |
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| 27 | bool BME280::begin(uint8_t a) {
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| 28 | _i2caddr = a;
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| 29 |
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| 30 | if (read8(BME280_REGISTER_CHIPID) != 0x60)
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| 31 | return false;
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| 32 |
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| 33 | readCoefficients();
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| 34 |
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| 35 | //Set before CONTROL_meas (DS 5.4.3)
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| 36 | write8(BME280_REGISTER_CONTROLHUMID, 0x05); //16x oversampling
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| 37 |
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| 38 | write8(BME280_REGISTER_CONTROL, 0xB7); // 16x ovesampling, normal mode
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| 39 | return true;
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| 40 | }
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| 41 |
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| 42 |
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| 43 | /**************************************************************************/
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| 44 | /*!
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| 45 | @brief Writes an 8 bit value over I2C/SPI
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| 46 | */
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| 47 | /**************************************************************************/
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| 48 | void BME280::write8(byte reg, byte value)
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| 49 | {
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| 50 | Wire.beginTransmission((uint8_t)_i2caddr);
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| 51 | Wire.write((uint8_t)reg);
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| 52 | Wire.write((uint8_t)value);
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| 53 | Wire.endTransmission();
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| 54 | }
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| 55 |
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| 56 | /**************************************************************************/
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| 57 | /*!
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| 58 | @brief Reads an 8 bit value over I2C
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| 59 | */
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| 60 | /**************************************************************************/
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| 61 | uint8_t BME280::read8(byte reg)
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| 62 | {
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| 63 | uint8_t value;
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| 64 |
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| 65 | Wire.beginTransmission((uint8_t)_i2caddr);
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| 66 | Wire.write((uint8_t)reg);
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| 67 | Wire.endTransmission();
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| 68 | Wire.requestFrom((uint8_t)_i2caddr, (byte)1);
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| 69 | value = Wire.read();
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| 70 | return value;
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| 71 | }
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| 72 |
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| 73 | /**************************************************************************/
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| 74 | /*!
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| 75 | @brief Reads a 16 bit value over I2C
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| 76 | */
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| 77 | /**************************************************************************/
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| 78 | uint16_t BME280::read16(byte reg)
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| 79 | {
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| 80 | uint16_t value;
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| 81 |
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| 82 | Wire.beginTransmission((uint8_t)_i2caddr);
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| 83 | Wire.write((uint8_t)reg);
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| 84 | Wire.endTransmission();
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| 85 | Wire.requestFrom((uint8_t)_i2caddr, (byte)2);
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| 86 | value = (Wire.read() << 8) | Wire.read();
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| 87 |
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| 88 | return value;
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| 89 | }
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| 90 |
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| 91 | uint16_t BME280::read16_LE(byte reg) {
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| 92 | uint16_t temp = read16(reg);
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| 93 | return (temp >> 8) | (temp << 8);
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| 94 |
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| 95 | }
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| 96 |
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| 97 | /**************************************************************************/
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| 98 | /*!
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| 99 | @brief Reads a signed 16 bit value over I2C
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| 100 | */
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| 101 | /**************************************************************************/
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| 102 | int16_t BME280::readS16(byte reg)
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| 103 | {
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| 104 | return (int16_t)read16(reg);
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| 105 |
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| 106 | }
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| 107 |
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| 108 | int16_t BME280::readS16_LE(byte reg)
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| 109 | {
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| 110 | return (int16_t)read16_LE(reg);
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| 111 |
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| 112 | }
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| 113 |
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| 114 |
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| 115 | /**************************************************************************/
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| 116 | /*!
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| 117 | @brief Reads a 24 bit value over I2C
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| 118 | */
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| 119 | /**************************************************************************/
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| 120 |
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| 121 | uint32_t BME280::read24(byte reg)
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| 122 | {
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| 123 | uint32_t value;
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| 124 |
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| 125 | Wire.beginTransmission((uint8_t)_i2caddr);
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| 126 | Wire.write((uint8_t)reg);
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| 127 | Wire.endTransmission();
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| 128 | Wire.requestFrom((uint8_t)_i2caddr, (byte)3);
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| 129 |
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| 130 | value = Wire.read();
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| 131 | value <<= 8;
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| 132 | value |= Wire.read();
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| 133 | value <<= 8;
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| 134 | value |= Wire.read();
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| 135 |
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| 136 | return value;
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| 137 | }
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| 138 |
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| 139 |
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| 140 | /**************************************************************************/
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| 141 | /*!
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| 142 | @brief Reads the factory-set coefficients
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| 143 | */
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| 144 | /**************************************************************************/
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| 145 | void BME280::readCoefficients(void)
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| 146 | {
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| 147 | _bme280_calib.dig_T1 = read16_LE(BME280_REGISTER_DIG_T1);
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| 148 | _bme280_calib.dig_T2 = readS16_LE(BME280_REGISTER_DIG_T2);
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| 149 | _bme280_calib.dig_T3 = readS16_LE(BME280_REGISTER_DIG_T3);
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| 150 |
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| 151 | _bme280_calib.dig_P1 = read16_LE(BME280_REGISTER_DIG_P1);
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| 152 | _bme280_calib.dig_P2 = readS16_LE(BME280_REGISTER_DIG_P2);
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| 153 | _bme280_calib.dig_P3 = readS16_LE(BME280_REGISTER_DIG_P3);
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| 154 | _bme280_calib.dig_P4 = readS16_LE(BME280_REGISTER_DIG_P4);
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| 155 | _bme280_calib.dig_P5 = readS16_LE(BME280_REGISTER_DIG_P5);
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| 156 | _bme280_calib.dig_P6 = readS16_LE(BME280_REGISTER_DIG_P6);
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| 157 | _bme280_calib.dig_P7 = readS16_LE(BME280_REGISTER_DIG_P7);
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| 158 | _bme280_calib.dig_P8 = readS16_LE(BME280_REGISTER_DIG_P8);
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| 159 | _bme280_calib.dig_P9 = readS16_LE(BME280_REGISTER_DIG_P9);
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| 160 |
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| 161 | _bme280_calib.dig_H1 = read8(BME280_REGISTER_DIG_H1);
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| 162 | _bme280_calib.dig_H2 = readS16_LE(BME280_REGISTER_DIG_H2);
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| 163 | _bme280_calib.dig_H3 = read8(BME280_REGISTER_DIG_H3);
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| 164 | _bme280_calib.dig_H4 = (read8(BME280_REGISTER_DIG_H4) << 4) | (read8(BME280_REGISTER_DIG_H4+1) & 0xF);
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| 165 | _bme280_calib.dig_H5 = (read8(BME280_REGISTER_DIG_H5+1) << 4) | (read8(BME280_REGISTER_DIG_H5) >> 4);
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| 166 | _bme280_calib.dig_H6 = (int8_t)read8(BME280_REGISTER_DIG_H6);
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| 167 | }
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| 168 |
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| 169 | /**************************************************************************/
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| 170 | /*!
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| 171 |
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| 172 | */
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| 173 | /**************************************************************************/
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| 174 | float BME280::temperature(void)
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| 175 | {
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| 176 | int32_t var1, var2;
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| 177 |
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| 178 | int32_t adc_T = read24(BME280_REGISTER_TEMPDATA);
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| 179 | adc_T >>= 4;
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| 180 |
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| 181 | var1 = ((((adc_T>>3) - ((int32_t)_bme280_calib.dig_T1 <<1))) *
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| 182 | ((int32_t)_bme280_calib.dig_T2)) >> 11;
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| 183 |
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| 184 | var2 = (((((adc_T>>4) - ((int32_t)_bme280_calib.dig_T1)) *
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| 185 | ((adc_T>>4) - ((int32_t)_bme280_calib.dig_T1))) >> 12) *
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| 186 | ((int32_t)_bme280_calib.dig_T3)) >> 14;
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| 187 |
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| 188 | t_fine = var1 + var2;
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| 189 |
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| 190 | float T = (t_fine * 5 + 128) >> 8;
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| 191 | return T/100;
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| 192 | }
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| 193 |
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| 194 | /**************************************************************************/
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| 195 | /*!
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| 196 |
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| 197 | */
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| 198 | /**************************************************************************/
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| 199 | float BME280::pressure(void) {
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| 200 | int64_t var1, var2, p;
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| 201 |
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| 202 | temperature(); // must be done first to get t_fine
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| 203 |
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| 204 | int32_t adc_P = read24(BME280_REGISTER_PRESSUREDATA);
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| 205 | adc_P >>= 4;
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| 206 |
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| 207 | var1 = ((int64_t)t_fine) - 128000;
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| 208 | var2 = var1 * var1 * (int64_t)_bme280_calib.dig_P6;
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| 209 | var2 = var2 + ((var1*(int64_t)_bme280_calib.dig_P5)<<17);
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| 210 | var2 = var2 + (((int64_t)_bme280_calib.dig_P4)<<35);
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| 211 | var1 = ((var1 * var1 * (int64_t)_bme280_calib.dig_P3)>>8) +
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| 212 | ((var1 * (int64_t)_bme280_calib.dig_P2)<<12);
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| 213 | var1 = (((((int64_t)1)<<47)+var1))*((int64_t)_bme280_calib.dig_P1)>>33;
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| 214 |
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| 215 | if (var1 == 0) {
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| 216 | return 0; // avoid exception caused by division by zero
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| 217 | }
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| 218 | p = 1048576 - adc_P;
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| 219 | p = (((p<<31) - var2)*3125) / var1;
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| 220 | var1 = (((int64_t)_bme280_calib.dig_P9) * (p>>13) * (p>>13)) >> 25;
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| 221 | var2 = (((int64_t)_bme280_calib.dig_P8) * p) >> 19;
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| 222 |
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| 223 | p = ((p + var1 + var2) >> 8) + (((int64_t)_bme280_calib.dig_P7)<<4);
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| 224 | return (float)p/256;
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| 225 | }
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| 226 |
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| 227 |
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| 228 | /**************************************************************************/
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| 229 | /*!
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| 230 |
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| 231 | */
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| 232 | /**************************************************************************/
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| 233 | float BME280::humidity(void) {
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| 234 |
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| 235 | temperature(); // must be done first to get t_fine
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| 236 |
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| 237 | int32_t adc_H = read16(BME280_REGISTER_HUMIDDATA);
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| 238 |
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| 239 | int32_t v_x1_u32r;
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| 240 |
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| 241 | v_x1_u32r = (t_fine - ((int32_t)76800));
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| 242 |
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| 243 | v_x1_u32r = (((((adc_H << 14) - (((int32_t)_bme280_calib.dig_H4) << 20) -
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| 244 | (((int32_t)_bme280_calib.dig_H5) * v_x1_u32r)) + ((int32_t)16384)) >> 15) *
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| 245 | (((((((v_x1_u32r * ((int32_t)_bme280_calib.dig_H6)) >> 10) *
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| 246 | (((v_x1_u32r * ((int32_t)_bme280_calib.dig_H3)) >> 11) + ((int32_t)32768))) >> 10) +
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| 247 | ((int32_t)2097152)) * ((int32_t)_bme280_calib.dig_H2) + 8192) >> 14));
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| 248 |
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| 249 | v_x1_u32r = (v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) *
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| 250 | ((int32_t)_bme280_calib.dig_H1)) >> 4));
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| 251 |
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| 252 | v_x1_u32r = (v_x1_u32r < 0) ? 0 : v_x1_u32r;
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| 253 | v_x1_u32r = (v_x1_u32r > 419430400) ? 419430400 : v_x1_u32r;
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| 254 | float h = (v_x1_u32r>>12);
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| 255 | return h / 1024.0;
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| 256 | }
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| 257 |
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| 258 | /**************************************************************************/
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| 259 | /*!
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| 260 | Calculates the altitude (in meters) from the specified atmospheric
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| 261 | pressure (in hPa), and sea-level pressure (in hPa).
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| 262 |
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| 263 | @param seaLevel Sea-level pressure in hPa
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| 264 | @param atmospheric Atmospheric pressure in hPa
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| 265 | */
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| 266 | /**************************************************************************/
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| 267 | float BME280::altitude(float seaLevel)
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| 268 | {
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| 269 | // Equation taken from BMP180 datasheet (page 16):
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| 270 | // http://www.adafruit.com/datasheets/BST-BMP180-DS000-09.pdf
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| 271 |
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| 272 | // Note that using the equation from wikipedia can give bad results
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| 273 | // at high altitude. See this thread for more information:
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| 274 | // http://forums.adafruit.com/viewtopic.php?f=22&t=58064
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| 275 |
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| 276 | float atmospheric = pressure() / 100.0F;
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| 277 | return 44330.0 * (1.0 - pow(atmospheric / seaLevel, 0.1903));
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| 278 | }
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| 279 |
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| 280 | BME280 bme280;
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