Diff: BMP085.cpp

Revision:

0:9a1682a09c50

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BMP085.cpp	Wed Jul 17 18:50:28 2013 +0000
@@ -0,0 +1,171 @@
+/*
+ * BMP085.cpp
+ *
+ *  Created on: 13 juil. 2013
+ *      Author: Vincent
+ */
+
+#include "BMP085.h"
+#include <new>
+
+BMP085::BMP085(PinName sda, PinName scl) : i2c_(*reinterpret_cast<I2C*>(i2cRaw))
+{
+    // Placement new to avoid additional heap memory allocation.
+    new(i2cRaw) I2C(sda, scl);
+
+    pressure = 101300;
+    temperature = 298;
+}
+
+BMP085::~BMP085()
+{
+    // If the I2C object is initialized in the buffer in this object, call destructor of it.
+    if(&i2c_ == reinterpret_cast<I2C*>(&i2cRaw))
+        reinterpret_cast<I2C*>(&i2cRaw)->~I2C();
+}
+
+// oversampling setting
+// 0 = ultra low power
+// 1 = standard
+// 2 = high
+// 3 = ultra high resolution
+const unsigned char oversampling_setting = 3; //oversampling for measurement
+const unsigned char pressure_conversiontime[4] = {4.5, 7.5, 13.5, 25.5 };  // delays for oversampling settings 0, 1, 2 and 3
+
+// sensor registers from the BOSCH BMP085 datasheet
+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;
+
+void BMP085::writeRegister(unsigned char r, unsigned char v)
+{
+  char cmd1[2];
+  cmd1[0] = r;
+  cmd1[1] = v;
+  i2c_.write(I2C_ADDRESS,cmd1, 2);
+}
+
+// read a 16 bit register
+int BMP085::readIntRegister(unsigned char r)
+{
+  char cmd1[2];
+  char cmd2[1];
+  //unsigned char msb, lsb;
+  cmd2[0] = r;
+  i2c_.write(I2C_ADDRESS,cmd2, 1);
+  i2c_.read(I2C_ADDRESS, cmd1, 2);
+  return (((int)cmd1[0]<<8) | ((int)cmd1[1]));
+}
+
+// read uncompensated temperature value
+unsigned int BMP085::readUT() {
+  writeRegister(0xf4,0x2e);
+  wait(0.0045); // the datasheet suggests 4.5 ms
+  return readIntRegister(0xf6);
+
+}
+
+// read uncompensated pressure value
+long BMP085::readUP() {
+  writeRegister(0xf4,0x34+(oversampling_setting<<6));
+  wait(pressure_conversiontime[oversampling_setting]*0.001);
+
+  //unsigned char msb, lsb, xlsb;
+  char cmd1[3];
+  char cmd0[1];
+  cmd0[0] = 0xf6;
+  i2c_.write(I2C_ADDRESS,cmd0, 1);
+  i2c_.read(I2C_ADDRESS, cmd1, 3);
+  return (((long)cmd1[0]<<16) | ((long)cmd1[1]<<8) | ((long)cmd1[2])) >>(8-oversampling_setting);
+
+}
+
+// Below there are the utility functions to get data from the sensor.
+
+// read temperature and pressure from sensor
+void BMP085::readSensor() {
+
+  long ut= readUT();
+  long up = readUP();
+
+
+  int x1, x2, x3, b3, b5, b6, p;
+  unsigned int b4, b7;
+  //calculate true temperature
+  x1 = ((long)ut - ac6) * ac5 >> 15;
+  x2 = ((long) mc << 11) / (x1 + md);
+  b5 = x1 + x2;
+  temperature = (b5 + 8) >> 4;
+
+  //calculate true pressure
+  b6 = b5 - 4000;
+  x1 = (b2 * (b6 * b6 >> 12)) >> 11;
+  x2 = ac2 * b6 >> 11;
+  x3 = x1 + x2;
+
+  if (oversampling_setting == 3) b3 = ((int32_t) ac1 * 4 + x3 + 2) << 1;
+  if (oversampling_setting == 2) b3 = ((int32_t) ac1 * 4 + x3 + 2);
+  if (oversampling_setting == 1) b3 = ((int32_t) ac1 * 4 + x3 + 2) >> 1;
+  if (oversampling_setting == 0) b3 = ((int32_t) ac1 * 4 + x3 + 2) >> 2;
+
+  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 >> oversampling_setting);
+  p = b7 < 0x80000000 ? (b7 * 2) / b4 : (b7 / b4) * 2;
+
+  x1 = (p >> 8) * (p >> 8);
+  x1 = (x1 * 3038) >> 16;
+  x2 = (-7357 * p) >> 16;
+  pressure = p + ((x1 + x2 + 3791) >> 4);
+}
+
+void  BMP085::getCalibrationData() {
+  ac1 = readIntRegister(0xAA);
+  ac2 = readIntRegister(0xAC);
+  ac3 = readIntRegister(0xAE);
+  ac4 = readIntRegister(0xB0);
+  ac5 = readIntRegister(0xB2);
+  ac6 = readIntRegister(0xB4);
+  b1 = readIntRegister(0xB6);
+  b2 = readIntRegister(0xB8);
+  mb = readIntRegister(0xBA);
+  mc = readIntRegister(0xBC);
+  md = readIntRegister(0xBE);
+}
+
+float BMP085::press(void)
+{
+    return(pressure);
+}
+
+float BMP085::temp(void)
+{
+    return(temperature);
+}
+
+float BMP085::altitud(void)
+{
+    //press();
+   // temp();
+    float To=298;
+    float ho=0;
+    float Po=101325;
+    //ecuacion
+    float c=(To-0.0065*ho);
+    float e=(pressure/Po);
+    float d=exp(0.19082*log(e));
+    float b=c*d;
+    float alt=153.84615*(To-b);
+    return(alt);
+}
+