Revision 0:e8f53e502a4c, committed 2015-03-19

Comitter:

timm

Date:

Thu Mar 19 03:46:13 2015 +0000

Commit message:

Bosch BMP085 I2C Driver

Changed in this revision

diff -r 000000000000 -r e8f53e502a4c bmp085.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/bmp085.cpp	Thu Mar 19 03:46:13 2015 +0000
@@ -0,0 +1,146 @@
+#include "mbed.h"
+#include "bmp085.h"
+
+BMP085::BMP085(PinName sclPin, PinName sdaPin)
+{
+    i2c = new I2C(sdaPin, sclPin);
+    i2c->frequency(1000); // run at 1KHz
+}
+
+long BMP085::getUT() { return UT; }
+long BMP085::getUP() { return UP; }
+void BMP085::init() { readCalData(); }
+
+void BMP085::readCalData()
+{
+    char dataWrite[2];
+    char dataRead[2];
+
+    dataWrite[0] = CAL_DATA_AC1;   
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 2, 0);
+    AC1 = ((dataRead[0] << 8) | (dataRead[1]));
+
+    dataWrite[0] = CAL_DATA_AC2;
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 2, 0);
+    AC2 = ((dataRead[0] << 8) | (dataRead[1]));
+
+    dataWrite[0] = CAL_DATA_AC3;
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 2, 0);
+    AC3 = ((dataRead[0] << 8) | (dataRead[1]));
+
+    dataWrite[0] = CAL_DATA_AC4;   
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 2, 0);
+    AC4 = ((dataRead[0] << 8) | (dataRead[1]));
+
+    dataWrite[0] = CAL_DATA_AC5;
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 2, 0);
+    AC5 = ((dataRead[0] << 8) | (dataRead[1]));
+
+    dataWrite[0] = CAL_DATA_AC6;
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 2, 0);
+    AC6 = ((dataRead[0] << 8) | (dataRead[1]));
+
+    dataWrite[0] = CAL_DATA_B1;   
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 2, 0);
+    B1 = ((dataRead[0] << 8) | (dataRead[1]));
+
+    dataWrite[0] = CAL_DATA_B2;
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 2, 0);
+    B2 = ((dataRead[0] << 8) | (dataRead[1]));
+
+    dataWrite[0] = CAL_DATA_MB;   
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 2, 0);
+    MB = ((dataRead[0] << 8) | (dataRead[1]));
+
+    dataWrite[0] = CAL_DATA_MC;
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 2, 0);
+    MC = ((dataRead[0] << 8) | (dataRead[1]));
+
+    dataWrite[0] = CAL_DATA_MD;
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 2, 0);
+    MD = ((dataRead[0] << 8) | (dataRead[1]));
+}
+
+void BMP085::readUncompTemp()
+{
+    char dataWrite[2];
+    char dataRead[2];
+
+    dataWrite[0] = CTRL_REG_ADDR;
+    dataWrite[1] = MEASURE_TEMP_CMD;
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 2, 0); // stop
+    wait_ms(5);
+    dataWrite[0] = DATA_REG_ADDR;
+    dataWrite[1] = 0;
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 2, 0);
+    UT = (long)((dataRead[0] << 8) | (dataRead[1]));
+}
+
+void BMP085::readUncompPressure(int mode)
+{
+    char dataWrite[2];
+    char dataRead[4];
+
+    dataWrite[0] = CTRL_REG_ADDR;
+    dataWrite[1] = (MEASURE_PRES_CMD | ((((char)mode) & 0x3) << 6));
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 2, 0); // stop
+    wait_ms(10 * (mode + 1)); // TODO: ensure this is accurate, based on oss
+    dataWrite[0] = DATA_REG_ADDR;
+    dataWrite[1] = 0;
+    i2c->write(BMP085_I2C_ADDR_WRITE, dataWrite, 1, 1); // no stop
+    i2c->read(BMP085_I2C_ADDR_READ, dataRead, 3, 0);
+    UP = (long)( ((dataRead[0] << 16) | (dataRead[1] << 8) | dataRead[0]) >> ( 8 - mode));
+    //UP = (long)((dataRead[0] << 8) | (dataRead[1]));
+}
+  
+float BMP085::getTemperature()
+{
+    readUncompTemp();
+
+    X1 = (((long)UT - (long)AC6)*(long)AC5) >> 15;
+    X2= ((long)MC << 11)/(X1+ MD);
+    B5 = X1 + X2;
+    T = ((B5 + 8) >> 4);
+    
+    return (float)(T / 10.0);
+}
+
+float BMP085::getPressure(int oss)
+{
+    readUncompPressure(oss);
+  
+    // Calculate B3
+    B6 = B5 - 4000;
+    X1 = (B2 * ((B6 * B6)>>12)) >>11;
+    X2 = (AC2 * B6)>>11;
+    X3 = X1 + X2;
+    B3 = (((((long)AC1) * 4 + X3) << oss) + 2) >> 2;
+
+    // Calculate B4, B7, p
+    X1 = (AC3 + B6) >> 13;
+    X2 = (B1 * ((B6 * B6) >> 12)) >> 16;
+    X3 = ((X1 + X2) + 2 ) >> 2;
+    B4 = (AC4 * (unsigned long)(X3 + 32768)) >> 15;
+    B7 = ((unsigned long)(UP - B3) * (50000 >> oss));
+    if (B7 < 0x80000000) { p = (B7 << 1) / B4; }
+    else { p = (B7/B4) << 1; }
+    
+    X1 = (p >> 8) * (p >> 8);
+    X1 = (X1 * 3038) >> 16;
+    X2 = (-7357 * p) >> 16;
+    p += ((X1 + X2 + 3791) >> 4);
+    
+    return (float)p;
+}
\ No newline at end of file

diff -r 000000000000 -r e8f53e502a4c bmp085.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/bmp085.h	Thu Mar 19 03:46:13 2015 +0000
@@ -0,0 +1,118 @@
+/**
+@file bmp085.h
+
+@brief Header file containing member functions and variables
+
+*/
+
+#ifndef __BMP085_H__
+#define __BMP085_H__
+
+#include "mbed.h"
+
+#define BMP085_I2C_ADDR_READ  (0xEF)
+#define BMP085_I2C_ADDR_WRITE (0xEE)
+
+#define CTRL_REG_ADDR (0xF4)
+#define DATA_REG_ADDR (0xF6)
+
+#define MEASURE_TEMP_CMD (0x2E)
+#define MEASURE_PRES_CMD (0x34)
+
+// MSB addresses, MSB first
+#define CAL_DATA_AC1    (0xAA)
+#define CAL_DATA_AC2    (0xAC)
+#define CAL_DATA_AC3    (0xAE)
+#define CAL_DATA_AC4    (0xB0)
+#define CAL_DATA_AC5    (0xB2)
+#define CAL_DATA_AC6    (0xB4)
+#define CAL_DATA_B1     (0xB6)
+#define CAL_DATA_B2     (0xB8)
+#define CAL_DATA_MB     (0xBA)
+#define CAL_DATA_MC     (0xBC)
+#define CAL_DATA_MD     (0xBE)
+
+
+/** 
+@brief Simple library for interfacing with Bosch BMP085
+
+@brief Revision 1.0
+
+@author Tim Meese
+@date   January 2015
+ *
+ * Example:
+ * @code
+ 
+ #include "mbed.h"
+ #include "bmp085.h"
+ 
+  
+ * @endcode
+ */
+
+
+class BMP085
+{
+
+private:
+
+    // I2C interface
+    I2C * i2c;
+ 
+    const float p0 = 101325;     // Pressure at sea level (Pa)
+    float altitude;
+   
+    // Calibration parameters
+    short AC1;
+    short AC2;
+    short AC3;
+    unsigned short AC4;
+    unsigned short AC5;
+    unsigned short AC6;
+    short B1;
+    short B2;
+    short MB;
+    short MC;
+    short MD;
+    
+    // uncalibrated temp, pressure
+    long UT;    
+    long UP;
+    
+    // shared values 
+    long X1;
+    long X2;
+    long X3;
+    long B3;
+    unsigned long B4;
+    long B5;
+    long B6;
+    unsigned long B7;
+    long T; // temp in 0.1 degrees C
+    long p; // pressure in Pascals
+
+    void readCalData();
+    void readUncompTemp();
+    void readUncompPressure(int mode);
+
+public:
+    /** Create a BMP085 object connected to the specified pins
+    *
+    * @param clkPin  Pin connected to clk
+    * @param dataPin Pin connected to data
+    * 
+    */
+    BMP085(PinName clkPin, PinName dataPin);
+    
+    /** Initialise SHT11
+    *
+    */
+    void init();
+    float getTemperature();
+    float getPressure(int oss);
+    long getUT();
+    long getUP();
+};
+
+#endif /* __BMP085_H__ */