BMP180.h

00001 /*
00002   @file BMP180.h
00003   
00004   @brief Barometric Pressure and Temperature Sensor BMP180 Breakout I2C Library      
00005 
00006   @Author spiridion (http://mailme.spiridion.net)
00007 
00008   Tested on LPC1768 and FRDM-KL25Z
00009   
00010   Copyright (c) 2014 spiridion
00011   Released under the MIT License (see http://mbed.org/license/mit)
00012 
00013   Documentation regarding the BMP180 can be found here: 
00014   http://mbed.org/media/uploads/spiridion/bst-bmp180-ds000-09.pdf
00015 */
00016 
00017 #ifndef BMP180_H
00018 #define BMP180_H
00019 
00020 #include "mbed.h"
00021 
00022 ///  default address is 0xEF 
00023 #define BMP180_I2C_ADDRESS 0xEF 
00024 
00025 // Oversampling settings
00026 #define BMP180_OSS_ULTRA_LOW_POWER 0        // 1 sample  and  4.5ms for conversion
00027 #define BMP180_OSS_NORMAL          1        // 2 samples and  7.5ms for conversion
00028 #define BMP180_OSS_HIGH_RESOLUTION 2        // 4 samples and 13.5ms for conversion
00029 #define BMP180_OSS_ULTRA_HIGH_RESOLUTION 3  // 8 samples and 25.5ms for conversion
00030 
00031 #define UNSET_BMP180_PRESSURE_VALUE 0.F
00032 #define UNSET_BMP180_TEMPERATURE_VALUE -273.15F // absolute zero
00033 
00034 /** BMP180 class.
00035  *  Read Pressure and temperature from the BMP180 Breakout I2C sensor
00036  *
00037  * Example:
00038  * @code
00039  * #include "mbed.h"
00040  * #include "BMP180.h"
00041  * 
00042  * #if defined(TARGET_LPC1768)
00043  *     #define PIN_SDA p9
00044  *     #define PIN_SCL p10
00045  * #elif defined(TARGET_KL25Z) // watch out for the PTE0/PTE1 mixed up in the KL25Z doc 
00046  *     #define PIN_SDA PTE0
00047  *     #define PIN_SCL PTE1
00048  * #endif
00049  * 
00050  * int main() 
00051  * {    
00052  *     BMP180 bmp180(PIN_SDA, PIN_SCL);
00053  *     float pressure, temperature;
00054  *     
00055  *     // bmp180.Initialize(); // no altitude compensation and normal oversampling 
00056  *     bmp180.Initialize(64, BMP180_OSS_ULTRA_LOW_POWER); // 64m altitude compensation and low power oversampling
00057  *     
00058  *     while(1) 
00059  *     {        
00060  *         if (bmp180.ReadData(&pressure, &temperature))
00061  *             printf("Pressure(hPa): %8.2f \t Temperature(C): %8.2f\n", pressure, temperature);  
00062  *         wait(1);
00063  *     }
00064  * }
00065  * @endcode
00066  */
00067 class BMP180 
00068 {
00069 
00070 public:
00071 
00072     /** Create a BMP180 instance
00073      * @param i2c object
00074      * @param address: I2C slave address 
00075      */
00076     BMP180(I2C *i2c, int address = BMP180_I2C_ADDRESS); 
00077 
00078     /** Initialization: set member values and read BMP180 calibration parameters
00079      * @param altitude (in meter)
00080      * @param overSamplingSetting 
00081      */
00082     int Initialize(float altitude = 0.F, int overSamplingSetting = BMP180_OSS_NORMAL);
00083 
00084     /** Read pressure and temperature from the BMP180.
00085      * @param pressure (hPa) 
00086      * @param temperature (C) 
00087      * @returns
00088      *   1 on success,
00089      *   0 on error
00090      */    
00091     int ReadData(float* pTemperature = NULL, float* pPressure = NULL);
00092     double ReadAltitude(double sealevelPressure=1029.5);
00093     /** Get temperature from a previous measurement 
00094      *  
00095      * @returns
00096      *   temperature (C)
00097      */    
00098     float GetTemperature() {return m_temperature;};
00099 
00100      /** Get pressure from a previous measurement 
00101      *  
00102      * @returns
00103      *   pressure (hPa)
00104      */    
00105    float GetPressure() {return m_pressure;};
00106 
00107 protected:
00108 
00109     /** Perform temperature measurement
00110      *  
00111      * @returns
00112      *   temperature (C)
00113      */    
00114     int ReadRawTemperature(long* pUt);
00115 
00116     /** Perform pressure measurement 
00117      *  
00118      * @returns
00119      *   temperature (C)
00120      */    
00121     int ReadRawPressure(long* pUp);
00122 
00123     /** Calculation of the temperature from the digital output
00124      */    
00125     float TrueTemperature(long ut);
00126 
00127     /** Calculation of the pressure from the digital output
00128      */    
00129     float TruePressure(long up);
00130 
00131     int m_oss;
00132     float m_temperature;     
00133     float m_pressure;
00134     float m_altitude;
00135 
00136     I2C *m_i2c;   
00137     int m_addr;
00138     char m_data[4];    
00139 
00140     short ac1, ac2, ac3; 
00141     unsigned short ac4, ac5, ac6;
00142     short b1, b2;
00143     short mb, mc, md;
00144     long x1, x2, x3, b3, b5, b6;
00145     unsigned long b4, b7;
00146 
00147 };
00148 
00149 #endif