mirror of https://github.com/ArduPilot/ardupilot
252 lines
7.3 KiB
C++
252 lines
7.3 KiB
C++
/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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/*
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* APM_BMP085.cpp - Arduino Library for BMP085 absolute pressure sensor
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* Code by Jordi Mu<4D>oz and Jose Julio. DIYDrones.com
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Sensor is conected to I2C port
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* Sensor End of Conversion (EOC) pin is PC7 (30)
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*
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* Variables:
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* RawTemp : Raw temperature data
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* RawPress : Raw pressure data
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*
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* Temp : Calculated temperature (in 0.1<EFBFBD>C units)
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* Press : Calculated pressure (in Pa units)
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*
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* Methods:
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* Init() : Initialization of I2C and read sensor calibration data
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* Read() : Read sensor data and calculate Temperature and Pressure
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* This function is optimized so the main host don<6F>t need to wait
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* You can call this function in your main loop
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* It returns a 1 if there are new data.
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*
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* Internal functions:
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* Command_ReadTemp(): Send commando to read temperature
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* Command_ReadPress(): Send commando to read Pressure
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* ReadTemp() : Read temp register
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* ReadPress() : Read press register
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* Calculate() : Calculate Temperature and Pressure in real units
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*
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*
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*/
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// AVR LibC Includes
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#include <inttypes.h>
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#include <AP_Common.h>
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#include <AP_Math.h> // ArduPilot Mega Vector/Matrix math Library
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#include <AP_HAL.h>
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#include "AP_Baro_BMP085.h"
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extern const AP_HAL::HAL& hal;
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#define BMP085_ADDRESS 0x77 //(0xEE >> 1)
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#define BMP085_EOC 30 // End of conversion pin PC7
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// the apm2 hardware needs to check the state of the
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// chip using a direct IO port
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// On APM2 prerelease hw, the data ready port is hooked up to PE7, which
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// is not available to the arduino digitalRead function.
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#if CONFIG_HAL_BOARD == HAL_BOARD_APM2
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#define BMP_DATA_READY() (PINE&0x80)
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#else
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#define BMP_DATA_READY() hal.gpio->read(BMP085_EOC)
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#endif
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// oversampling 3 gives highest resolution
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#define OVERSAMPLING 3
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// Public Methods //////////////////////////////////////////////////////////////
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bool AP_Baro_BMP085::init()
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{
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uint8_t buff[22];
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hal.gpio->pinMode(BMP085_EOC, GPIO_INPUT);// End Of Conversion (PC7) input
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BMP085_State = 0; // Initial state
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// We read the calibration data registers
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if (hal.i2c->readRegisters(BMP085_ADDRESS, 0xAA, 22, buff) != 0) {
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healthy = false;
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return false;
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}
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hal.console->println_P(PSTR("read bmp085 calibration regs"));
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ac1 = ((int)buff[0] << 8) | buff[1];
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ac2 = ((int)buff[2] << 8) | buff[3];
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ac3 = ((int)buff[4] << 8) | buff[5];
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ac4 = ((int)buff[6] << 8) | buff[7];
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ac5 = ((int)buff[8] << 8) | buff[9];
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ac6 = ((int)buff[10] << 8) | buff[11];
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b1 = ((int)buff[12] << 8) | buff[13];
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b2 = ((int)buff[14] << 8) | buff[15];
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mb = ((int)buff[16] << 8) | buff[17];
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mc = ((int)buff[18] << 8) | buff[19];
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md = ((int)buff[20] << 8) | buff[21];
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//Send a command to read Temp
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Command_ReadTemp();
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hal.console->println_P(PSTR("read bmp085 temp"));
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BMP085_State = 1;
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// init raw temo
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RawTemp = 0;
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healthy = true;
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return true;
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}
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// Read the sensor. This is a state machine
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// We read Temperature (state=1) and then Pressure (state!=1) on alternate calls
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uint8_t AP_Baro_BMP085::read()
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{
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uint8_t result = 0;
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if (BMP085_State == 1) {
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if (BMP_DATA_READY()) {
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BMP085_State = 2;
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ReadTemp(); // On state 1 we read temp
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Command_ReadPress();
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}
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}else{
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if (BMP_DATA_READY()) {
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BMP085_State = 1; // Start again from state = 1
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ReadPress();
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Calculate();
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Command_ReadTemp(); // Read Temp
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result = 1; // New pressure reading
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}
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}
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if (result) {
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_last_update = hal.scheduler->millis();
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}
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return(result);
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}
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float AP_Baro_BMP085::get_pressure() {
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return Press;
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}
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float AP_Baro_BMP085::get_temperature() {
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return Temp;
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}
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int32_t AP_Baro_BMP085::get_raw_pressure() {
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return RawPress;
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}
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int32_t AP_Baro_BMP085::get_raw_temp() {
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return RawTemp;
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}
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// Private functions: /////////////////////////////////////////////////////////
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// Send command to Read Pressure
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void AP_Baro_BMP085::Command_ReadPress()
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{
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uint8_t res = hal.i2c->writeRegister(BMP085_ADDRESS, 0xF4,
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0x34+(OVERSAMPLING << 6));
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if (res != 0) {
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healthy = false;
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}
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}
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// Read Raw Pressure values
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void AP_Baro_BMP085::ReadPress()
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{
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uint8_t buf[3];
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if (!healthy && hal.scheduler->millis() < _retry_time) {
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return;
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}
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if (hal.i2c->readRegisters(BMP085_ADDRESS, 0xF6, 3, buf) != 0) {
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_retry_time = hal.scheduler->millis() + 1000;
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hal.i2c->setHighSpeed(false);
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healthy = false;
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return;
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}
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RawPress = (((uint32_t)buf[0] << 16)
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| ((uint32_t)buf[1] << 8)
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| ((uint32_t)buf[2])) >> (8 - OVERSAMPLING);
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}
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// Send Command to Read Temperature
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void AP_Baro_BMP085::Command_ReadTemp()
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{
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if (hal.i2c->writeRegister(BMP085_ADDRESS, 0xF4, 0x2E) != 0) {
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healthy = false;
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}
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}
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// Read Raw Temperature values
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void AP_Baro_BMP085::ReadTemp()
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{
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uint8_t buf[2];
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int32_t _temp_sensor;
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if (!healthy && hal.scheduler->millis() < _retry_time) {
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return;
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}
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if (hal.i2c->readRegisters(BMP085_ADDRESS, 0xF6, 2, buf) != 0) {
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_retry_time = hal.scheduler->millis() + 1000;
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hal.i2c->setHighSpeed(false);
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healthy = false;
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return;
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}
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_temp_sensor = buf[0];
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_temp_sensor = (_temp_sensor << 8) | buf[1];
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RawTemp = _temp_filter.apply(_temp_sensor);
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}
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// Calculate Temperature and Pressure in real units.
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void AP_Baro_BMP085::Calculate()
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{
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int32_t x1, x2, x3, b3, b5, b6, p;
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uint32_t b4, b7;
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int32_t tmp;
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// See Datasheet page 13 for this formulas
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// Based also on Jee Labs BMP085 example code. Thanks for share.
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// Temperature calculations
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x1 = ((int32_t)RawTemp - ac6) * ac5 >> 15;
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x2 = ((int32_t) mc << 11) / (x1 + md);
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b5 = x1 + x2;
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Temp = (b5 + 8) >> 4;
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// Pressure calculations
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b6 = b5 - 4000;
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x1 = (b2 * (b6 * b6 >> 12)) >> 11;
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x2 = ac2 * b6 >> 11;
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x3 = x1 + x2;
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//b3 = (((int32_t) ac1 * 4 + x3)<<OVERSAMPLING + 2) >> 2; // BAD
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//b3 = ((int32_t) ac1 * 4 + x3 + 2) >> 2; //OK for OVERSAMPLING=0
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tmp = ac1;
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tmp = (tmp*4 + x3)<<OVERSAMPLING;
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b3 = (tmp+2)/4;
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x1 = ac3 * b6 >> 13;
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x2 = (b1 * (b6 * b6 >> 12)) >> 16;
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x3 = ((x1 + x2) + 2) >> 2;
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b4 = (ac4 * (uint32_t) (x3 + 32768)) >> 15;
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b7 = ((uint32_t) RawPress - b3) * (50000 >> OVERSAMPLING);
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p = b7 < 0x80000000 ? (b7 * 2) / b4 : (b7 / b4) * 2;
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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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Press = p + ((x1 + x2 + 3791) >> 4);
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}
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