Diff: BMP085_sam.cpp

Revision:

0:ad2afb285975

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BMP085_sam.cpp	Fri Oct 14 18:44:39 2011 +0000
@@ -0,0 +1,152 @@
+/*
+   * mbed library to use a Bosch Sensortec BMP085 sensor
+   * Copyright (c) 2010 Hiroshi Suga
+   * Released under the MIT License: http://mbed.org/license/mit
+   */
+  
+  /** @file BMP085.cpp
+   * @brief mbed library to use a Bosch Sensortec BMP085 sensor
+   * barometric pressure sensor BMP085 (Bosch Sensortec)
+   * interface: I2C digital
+   */
+  
+  #include "mbed.h"
+  #include "BMP085.h"
+  
+  #define WEATHER_BMP085 0xee
+  #define xpow(x, y) ((long)1 << y)
+  
+  /**
+   * @brief Initializes interface (private I2C)
+   * @param p_sda port of I2C SDA
+   * @param p_scl port of I2C SCL
+   * @param p_oss parameter of OSS
+   */
+  BMP085::BMP085 (PinName p_sda, PinName p_scl, BMP085_oss p_oss) : i2c(p_sda, p_scl) {
+      init(p_oss);
+  }
+  
+  /**
+   * @brief Initializes interface (public I2C)
+   * @param p_i2c instance of I2C class
+   * @param p_oss parameter of OSS
+   */
+  BMP085::BMP085 (I2C& p_i2c, BMP085_oss p_oss) : i2c(p_i2c) { 
+      init(p_oss);
+  }
+  
+  /**
+   * @brief Get temperature
+   * @return temperature (`C)
+   */
+  float BMP085::get_temperature() {
+      return temperature;
+  }
+  
+  /**
+   * @brief Get pressure
+   * @return pressure (hPa)
+   */
+  float BMP085::get_pressure() {
+      return pressure;
+  }
+  
+  /**
+   * @brief Update results
+   */
+  void BMP085::update () {
+      long t, p, ut, up, x1, x2, x3, b3, b5, b6;
+      unsigned long b4, b7;
+  
+      twi_writechar(WEATHER_BMP085, 0xf4, 0x2e);
+      wait(0.01);
+      ut = twi_readshort(WEATHER_BMP085, 0xf6);
+  
+      twi_writechar(WEATHER_BMP085, 0xf4, 0x34 | (oss << 6));
+      wait(0.05);
+      up = twi_readlong(WEATHER_BMP085, 0xf6) >> (8 - oss);
+  
+      x1 = ((ut - ac6) * ac5) / xpow(2, 15);
+      x2 = ((long)mc * xpow(2, 11)) / (x1 + md);
+      b5 = x1 + x2;
+      t = (b5 + 8) / xpow(2, 4);
+      temperature = (float)t / 10.0;
+  
+      b6 = b5 - 4000;
+      x1 = (b2 * (b6 * b6 / xpow(2, 12))) / xpow(2, 11);
+      x2 = (ac2 * b6) / xpow(2, 11);
+      x3 = x1 + x2;
+      b3 = ((((unsigned long)ac1 * 4 + x3) << oss) + 2) / 4;
+      x1 = ac3 * b6 / xpow(2, 13);
+      x2 = (b1 * (b6 * b6 / xpow(2, 12))) / xpow(2, 16);
+      x3 = ((x1 + x2) + 2) / xpow(2, 2);
+      b4 = (ac4 * (unsigned long)(x3 + 32768)) / xpow(2, 15);
+      b7 = ((unsigned long)up - b3) * (50000 >> oss);
+      if (b7 < (unsigned long)0x80000000) {
+          p = (b7 * 2) / b4;
+      } else {
+          p = (b7 / b4) * 2;
+      }
+      x1 = (p / xpow(2, 8)) * (p / xpow(2, 8));
+      x1 = (x1 * 3038) / xpow(2, 16);
+      x2 = (-7357 * p) / xpow(2, 16);
+      p = p + (x1 + x2 + 3791) / xpow(2, 4);
+      pressure = (float)p / 100.0;
+  }
+  
+  void BMP085::init (BMP085_oss p_oss) {
+      ac1 = twi_readshort(WEATHER_BMP085, 0xaa);
+      ac2 = twi_readshort(WEATHER_BMP085, 0xac);
+      ac3 = twi_readshort(WEATHER_BMP085, 0xae);
+      ac4 = twi_readshort(WEATHER_BMP085, 0xb0);
+      ac5 = twi_readshort(WEATHER_BMP085, 0xb2);
+      ac6 = twi_readshort(WEATHER_BMP085, 0xb4);
+      b1 = twi_readshort(WEATHER_BMP085, 0xb6);
+      b2 = twi_readshort(WEATHER_BMP085, 0xb8);
+      mb = twi_readshort(WEATHER_BMP085, 0xba);
+      mc = twi_readshort(WEATHER_BMP085, 0xbc);
+      md = twi_readshort(WEATHER_BMP085, 0xbe);
+      oss = p_oss;
+  }
+  
+  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();
+  }
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