BMP180.h

00001 /*
00002   @file BMP180.h
00003   @brief Barometric Pressure and Temperature Sensor BMP180 Breakout I2C Library
00004 */
00005 
00006 #ifndef BMP180_H
00007 #define BMP180_H
00008 
00009 #include "mbed.h"
00010 
00011 ///  default address is 0xEF => (0x77<<1 + 1)
00012 #define BMP180_I2C_ADDRESS  0xEF
00013 #define DEGREES             '\u00B0'
00014 #define DEGREES_CELCIUS     "\u00B0C"
00015 
00016 // Oversampling settings
00017 typedef enum {
00018     ULTRA_LOW_POWER       = 0, ///< 1 pressure sample  :  4.5 ms delay
00019     STANDARD              = 1, ///< 2 pressure samples :  7.5 ms delay
00020     HIGH_RESOLUTION       = 2, ///< 4 pressure samples : 13.5 ms delay
00021     ULTRA_HIGH_RESOLUTION = 3  ///< 8 pressure samples : 25.5 ms delay
00022 } OverSamplingSetting;
00023 
00024 /** BMP180 class.
00025  *  Read Pressure and temperature from the BMP180 Breakout I2C sensor
00026  *
00027  * Example:
00028  * @code
00029  * #include "mbed.h"
00030  * #include "BMP180.h"
00031  *
00032  * int main() {
00033  *     BMP180 bmp180(PIN_SDA, PIN_SCL);
00034  *     float pressure, temperature;
00035  *
00036  *     // bmp180.Initialize(); // no altitude compensation and normal oversampling
00037  *     bmp180.Initialize(64, BMP180_OSS_ULTRA_LOW_POWER); // 64m altitude compensation and low power oversampling
00038  *
00039  *     while(1) {
00040  *         if (bmp180.ReadData(&pressure, &temperature))
00041  *             printf("Pressure(hPa): %8.2f \t Temperature(C): %8.2f\n", pressure, temperature);
00042  *         wait(1);
00043  *     }
00044  * }
00045  * @endcode
00046  */
00047 class BMP180 {
00048     public:
00049         /** Create a BMP180 instance
00050          * @param i2c object
00051          */
00052         BMP180(I2C& i2c);
00053 
00054         /** Initialization: set member values and read BMP180 calibration parameters
00055          * @param altitude (in meter)
00056          * @param overSamplingSetting
00057          * @returns
00058          *   1 on success,
00059          *   0 on error
00060          */
00061         int initialize(float altitude = 0.F, OverSamplingSetting oss = STANDARD);
00062 
00063         /** Read pressure and temperature from the BMP180.
00064          * @param pressure (hPa)
00065          * @param temperature (C)
00066          * @returns
00067          *   1 on success,
00068          *   0 on error
00069          */
00070         int readData(float& pTemperature, float& pPressure);
00071 
00072     protected:
00073         /** Perform temperature measurement
00074          *
00075          * @returns
00076          *   temperature (C)
00077          */
00078         int ReadRawTemperature(long* pUt);
00079 
00080         /** Perform pressure measurement
00081          *
00082          * @returns
00083          *   pressure (mbar)
00084          */
00085         int ReadRawPressure(long* pUp);
00086 
00087         /** Calculation of the temperature from the digital output
00088          */
00089         float TrueTemperature(long ut);
00090 
00091         /** Calculation of the pressure from the digital output
00092          */
00093         float TruePressure(long up);
00094 
00095         OverSamplingSetting m_oss;
00096         float m_altitude;
00097 
00098         I2C m_i2c;
00099         char m_data[2];
00100 
00101         //short mb; // Not used?
00102         uint16_t ac4, ac5, ac6;
00103         int16_t ac1, ac2, ac3, b1, b2, b5, md;
00104         long x1, x2, x3, b3, b6, mc;
00105         unsigned long b4, b7;
00106 };
00107 
00108 #endif //BMP180_H