Diff: BMP085.cpp

Revision:

0:d07617f8ede9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BMP085.cpp	Mon Oct 17 19:43:06 2011 +0000
@@ -0,0 +1,206 @@
+/*
+ * 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);
+    ok=0;
+}
+
+/**
+ * @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);
+    ok=0;
+}
+
+/**
+ * @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 Get altitude e
+ * @return altitude (m)
+ */
+float BMP085::get_altitude() 
+{
+    return altitude;
+}
+
+
+/**
+ * @brief Update results
+ */
+void BMP085::update () 
+{
+   static long t, p, ut, up, x1, x2, x3, b3, b5, b6;
+   static unsigned long b4, b7;
+   static unsigned int nbtick=0;
+
+    switch(nbtick){
+        case 0 : twi_writechar(WEATHER_BMP085, 0xf4, 0x2e);
+                 nbtick=1;
+                 break;
+        case 1 : ut = twi_readshort(WEATHER_BMP085, 0xf6);
+                 twi_writechar(WEATHER_BMP085, 0xf4, 0x34 | (oss << 6));
+                 nbtick=2;
+                 break;
+        case 2 :
+        case 3 :
+        case 4 :
+        case 5 :
+        case 6 :
+        //case 7 : 
+                 nbtick++;
+                 break;
+        case 7 : 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;
+                 ok=1;
+                 nbtick=0;
+                 break;
+         default: nbtick=0; 
+                  break;
+      }
+    /*float To=231; // 298    273,15 + 25
+    float ho=0;
+    float Po=102400; //101325
+    //ecuacion
+    float c=(To-0.0065*ho);
+    float e=(p/Po);
+    float d=exp(0.19082*log(e));  
+    float b=c*d;
+    altitude = 153.84615*(To-b); 
+    
+   /*altitude = (float)44330 * (1 - pow(((float) pressure/Po), 0.190295));
+    float A = pressure/1024.00;
+    float B = 1/5.25588;
+    altitude = pow(A,B);
+    altitude = 1 - altitude;
+    altitude = altitude /0.0000225577;*/
+    
+    
+
+
+    
+}
+
+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();
+}
+