Diff: BMP085/BMP085.cpp

Revision:

5:818c0668fd2d

Child:

9:4e0c3936c756

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BMP085/BMP085.cpp	Sat Oct 13 08:59:03 2012 +0000
@@ -0,0 +1,147 @@
+
+#include "mbed.h"
+#include "BMP085.h"
+
+//I2C Adresse
+#define BMP085_ADRESS 0xEE
+
+#define xpow(x, y) ((long)1 << y)
+
+
+// Constructor
+// -----------------------------------------------
+BMP085::BMP085(PinName sda, PinName scl) : i2c_(sda, scl)
+    {
+    Init();
+    }
+    
+
+// Temperatur und Druck auslesen und berechnen
+// -----------------------------------------------
+void BMP085::Update () 
+    {
+    long P, UTemp, UPressure, X1, X2, X3, B3, B5, B6;
+    unsigned long B4, B7;
+
+    twi_writechar(BMP085_ADRESS, 0xf4, 0x2e);
+    // Wait at least 4.5ms
+    wait(0.005);
+    UTemp = twi_readshort(BMP085_ADRESS, 0xf6);
+    
+    X1 = ((UTemp - AC6) * AC5) >> 15;
+    X2 = (MC << 11) / (X1 + MD);
+    B5 = X1 + X2;
+    Temperature = (float)((B5 + 8) >> 4)/10.0;
+
+    twi_writechar(BMP085_ADRESS, 0xf4, 0x34 + (oss << 6));
+    // Wait at least 4.5ms
+    wait(0.005);
+    UPressure = twi_readlong(BMP085_ADRESS, 0xf6) >> (8 - oss);
+
+    B6 = B5 - 4000;
+    X1 = (B2 * (B6 * B6) >> 12) >> 11;
+    X2 = (AC2 * B6) >> 11;
+    X3 = X1 + X2;
+    B3 = ((AC1 * 4 + X3) << oss) >> 2;    
+
+    X1 = (AC3 * B6) >> 13;
+    X2 = (B1 * (B6 * B6) >> 12) >> 16;
+    X3 = ((X1 + X2) + 2) >> 2;
+    B4 = AC4 * (X3 + 32768) >> 15;
+    
+    B7 = (unsigned long)(UPressure - B3) * (50000 >> oss);
+    
+    if (B7 < 0x80000000) 
+        {
+        P = (2 * B7) / B4;
+        }
+    else 
+        {
+        P = 2* (B7 / B4);
+        }
+    X1 = (P >> 8) * (P >> 8);
+    X1 = (X1 * 3038) >> 16;
+    X2 = (-7357 * P) >> 16;    
+    P = P + ((X1 + X2 + 3791) >> 4);
+    Pressure = (float)P / 100.0;
+    }
+
+
+// Hoehe u.M. berechnen  (Druck in hPa)
+// -----------------------------------------------
+float BMP085::CalcAltitude(float Press)
+    {
+    float A = Press/1013.25;
+    float B = 1/5.25588;
+    float C = pow(A,B);
+    
+    C = 1 - C;
+    C = C / 22.5577e-6;
+    return C;
+    }
+    
+        
+// Drucksensor initialisieren  
+// -----------------------------------------------
+void BMP085::Init () 
+    {
+    AC1 = twi_readshort(BMP085_ADRESS, 0xaa);
+    AC2 = twi_readshort(BMP085_ADRESS, 0xac);
+    AC3 = twi_readshort(BMP085_ADRESS, 0xae);
+    AC4 = twi_readshort(BMP085_ADRESS, 0xb0);
+    AC5 = twi_readshort(BMP085_ADRESS, 0xb2);
+    AC6 = twi_readshort(BMP085_ADRESS, 0xb4);
+    B1 = twi_readshort(BMP085_ADRESS, 0xb6);
+    B2 = twi_readshort(BMP085_ADRESS, 0xb8);
+    MB = twi_readshort(BMP085_ADRESS, 0xba);
+    MC = twi_readshort(BMP085_ADRESS, 0xbc);
+    MD = twi_readshort(BMP085_ADRESS, 0xbe);
+    }
+    
+    
+// -----------------------------------------------
+unsigned short BMP085::twi_readshort (int id, int addr) {
+    unsigned short i;
+
+    i2c_.start();
+    i2c_.write(id);
+    i2c_.write(addr);
+
+    i2c_.start();
+    i2c_.write(id | 1);
+    i = i2c_.read(1) << 8;
+    i |= i2c_.read(0);
+    i2c_.stop();
+
+    return i;
+}
+
+
+// -----------------------------------------------
+unsigned long BMP085::twi_readlong (int id, int addr) {
+    unsigned long i;
+
+    i2c_.start();
+    i2c_.write(id);
+    i2c_.write(addr);
+
+    i2c_.start();
+    i2c_.write(id | 1);
+    i = i2c_.read(1) << 16;
+    i |= i2c_.read(1) << 8;
+    i |= i2c_.read(0);
+    i2c_.stop();
+
+    return i;
+}
+
+
+// -----------------------------------------------
+void BMP085::twi_writechar (int id, int addr, int dat) {
+
+    i2c_.start();
+    i2c_.write(id);
+    i2c_.write(addr);
+    i2c_.write(dat);
+    i2c_.stop();
+}