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253 lines
8.1 KiB
253 lines
8.1 KiB
// -----------------------------------------------------------------------------
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// BMP085/BMP180 Sensor over I2C
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// Copyright (C) 2018 by Xose Pérez <xose dot perez at gmail dot com>
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// -----------------------------------------------------------------------------
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#if SENSOR_SUPPORT && BMP180_SUPPORT
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#pragma once
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#undef I2C_SUPPORT
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#define I2C_SUPPORT 1 // Explicitly request I2C support.
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#include "Arduino.h"
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#include "I2CSensor.h"
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#define BMP180_CHIP_ID 0x55
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#define BMP180_REGISTER_CHIPID 0xD0
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#define BMP180_REGISTER_CAL_AC1 0xAA
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#define BMP180_REGISTER_CAL_AC2 0xAC
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#define BMP180_REGISTER_CAL_AC3 0xAE
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#define BMP180_REGISTER_CAL_AC4 0xB0
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#define BMP180_REGISTER_CAL_AC5 0xB2
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#define BMP180_REGISTER_CAL_AC6 0xB4
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#define BMP180_REGISTER_CAL_B1 0xB6
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#define BMP180_REGISTER_CAL_B2 0xB8
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#define BMP180_REGISTER_CAL_MB 0xBA
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#define BMP180_REGISTER_CAL_MC 0xBC
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#define BMP180_REGISTER_CAL_MD 0xBE
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#define BMP180_REGISTER_VERSION 0xD1
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#define BMP180_REGISTER_SOFTRESET 0xE0
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#define BMP180_REGISTER_CONTROL 0xF4
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#define BMP180_REGISTER_TEMPDATA 0xF6
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#define BMP180_REGISTER_PRESSUREDATA 0xF6
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#define BMP180_REGISTER_READTEMPCMD 0x2E
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#define BMP180_REGISTER_READPRESSURECMD 0x34
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class BMP180Sensor : public I2CSensor {
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public:
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static unsigned char addresses[1];
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// ---------------------------------------------------------------------
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// Public
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// ---------------------------------------------------------------------
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BMP180Sensor(): I2CSensor() {
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_sensor_id = SENSOR_BMP180_ID;
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_count = 2;
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}
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// ---------------------------------------------------------------------
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// Sensor API
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// ---------------------------------------------------------------------
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// Initialization method, must be idempotent
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void begin() {
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if (!_dirty) return;
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_init();
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_dirty = !_ready;
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}
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// Descriptive name of the sensor
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String description() {
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char buffer[20];
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snprintf(buffer, sizeof(buffer), "BMP180 @ I2C (0x%02X)", _address);
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return String(buffer);
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}
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// Type for slot # index
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unsigned char type(unsigned char index) {
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if (index == 0) return MAGNITUDE_TEMPERATURE;
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if (index == 1) return MAGNITUDE_PRESSURE;
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return MAGNITUDE_NONE;
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}
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// Pre-read hook (usually to populate registers with up-to-date data)
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virtual void pre() {
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if (_run_init) {
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i2cClearBus();
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_init();
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}
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if (_chip == 0) {
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_error = SENSOR_ERROR_UNKNOWN_ID;
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return;
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}
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_error = SENSOR_ERROR_OK;
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_error = _read();
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if (_error != SENSOR_ERROR_OK) {
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_run_init = true;
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}
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}
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// Current value for slot # index
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double value(unsigned char index) {
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if (index == 0) return _temperature;
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if (index == 1) return _pressure / 100;
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return 0;
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}
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protected:
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void _init() {
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// Make sure sensor had enough time to turn on. BMP180 requires 2ms to start up
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nice_delay(10);
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// I2C auto-discover
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_address = _begin_i2c(_address, sizeof(BMP180Sensor::addresses), BMP180Sensor::addresses);
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if (_address == 0) return;
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// Check sensor correctly initialized
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_chip = i2c_read_uint8(_address, BMP180_REGISTER_CHIPID);
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if (_chip != BMP180_CHIP_ID) {
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_chip = 0;
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i2cReleaseLock(_address);
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_previous_address = 0;
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_error = SENSOR_ERROR_UNKNOWN_ID;
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// Setting _address to 0 forces auto-discover
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// This might be necessary at this stage if there is a
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// different sensor in the hardcoded address
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_address = 0;
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return;
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}
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_readCoefficients();
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_run_init = false;
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_ready = true;
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}
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void _readCoefficients() {
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_bmp180_calib.ac1 = i2c_read_int16(_address, BMP180_REGISTER_CAL_AC1);
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_bmp180_calib.ac2 = i2c_read_int16(_address, BMP180_REGISTER_CAL_AC2);
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_bmp180_calib.ac3 = i2c_read_int16(_address, BMP180_REGISTER_CAL_AC3);
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_bmp180_calib.ac4 = i2c_read_uint16(_address, BMP180_REGISTER_CAL_AC4);
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_bmp180_calib.ac5 = i2c_read_uint16(_address, BMP180_REGISTER_CAL_AC5);
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_bmp180_calib.ac6 = i2c_read_uint16(_address, BMP180_REGISTER_CAL_AC6);
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_bmp180_calib.b1 = i2c_read_int16(_address, BMP180_REGISTER_CAL_B1);
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_bmp180_calib.b2 = i2c_read_int16(_address, BMP180_REGISTER_CAL_B2);
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_bmp180_calib.mb = i2c_read_int16(_address, BMP180_REGISTER_CAL_MB);
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_bmp180_calib.mc = i2c_read_int16(_address, BMP180_REGISTER_CAL_MC);
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_bmp180_calib.md = i2c_read_int16(_address, BMP180_REGISTER_CAL_MD);
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}
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// Compute B5 coefficient used in temperature & pressure calcs.
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// Based on Adafruit_BMP085_Unified library
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long _computeB5(unsigned long t) {
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long X1 = (t - (long)_bmp180_calib.ac6) * ((long)_bmp180_calib.ac5) >> 15;
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long X2 = ((long)_bmp180_calib.mc << 11) / (X1+(long)_bmp180_calib.md);
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return X1 + X2;
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}
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unsigned char _read() {
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// Read raw temperature
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i2c_write_uint8(_address, BMP180_REGISTER_CONTROL, BMP180_REGISTER_READTEMPCMD);
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nice_delay(5);
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unsigned long t = i2c_read_uint16(_address, BMP180_REGISTER_TEMPDATA);
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// Compute B5 coeficient
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long b5 = _computeB5(t);
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// Final temperature
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_temperature = ((double) ((b5 + 8) >> 4)) / 10.0;
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// Read raw pressure
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i2c_write_uint8(_address, BMP180_REGISTER_CONTROL, BMP180_REGISTER_READPRESSURECMD + (_mode << 6));
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nice_delay(26);
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unsigned long p1 = i2c_read_uint16(_address, BMP180_REGISTER_PRESSUREDATA);
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unsigned long p2 = i2c_read_uint8(_address, BMP180_REGISTER_PRESSUREDATA+2);
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long p = ((p1 << 8) + p2) >> (8 - _mode);
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// Pressure compensation
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long b6 = b5 - 4000;
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long x1 = (_bmp180_calib.b2 * ((b6 * b6) >> 12)) >> 11;
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long x2 = (_bmp180_calib.ac2 * b6) >> 11;
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long x3 = x1 + x2;
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long b3 = (((((int32_t) _bmp180_calib.ac1) * 4 + x3) << _mode) + 2) >> 2;
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x1 = (_bmp180_calib.ac3 * b6) >> 13;
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x2 = (_bmp180_calib.b1 * ((b6 * b6) >> 12)) >> 16;
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x3 = ((x1 + x2) + 2) >> 2;
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unsigned long b4 = (_bmp180_calib.ac4 * (uint32_t) (x3 + 32768)) >> 15;
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unsigned long b7 = ((uint32_t) (p - b3) * (50000 >> _mode));
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if (b7 < 0x80000000) {
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p = (b7 << 1) / b4;
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} else {
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p = (b7 / b4) << 1;
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}
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x1 = (p >> 8) * (p >> 8);
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x1 = (x1 * 3038) >> 16;
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x2 = (-7357 * p) >> 16;
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_pressure = p + ((x1 + x2 + 3791) >> 4);
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return SENSOR_ERROR_OK;
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}
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// ---------------------------------------------------------------------
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unsigned char _chip;
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bool _run_init = false;
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double _temperature = 0;
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double _pressure = 0;
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unsigned int _mode = BMP180_MODE;
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typedef struct {
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int16_t ac1;
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int16_t ac2;
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int16_t ac3;
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uint16_t ac4;
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uint16_t ac5;
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uint16_t ac6;
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int16_t b1;
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int16_t b2;
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int16_t mb;
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int16_t mc;
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int16_t md;
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} bmp180_calib_t;
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bmp180_calib_t _bmp180_calib;
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};
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// Static inizializations
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unsigned char BMP180Sensor::addresses[1] = {0x77};
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#endif // SENSOR_SUPPORT && BMP180_SUPPORT
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