gavin beardall / Mbed 2 deprecated bmp085_lib

Dependencies:   mbed

BMP085/BMP085.cpp@0:2005beefb93e, 2011-10-17 (annotated)

Committer:
gbeardall
Date:
Mon Oct 17 10:41:08 2011 +0000
Revision:
0:2005beefb93e

        

        
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/*





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 * mbed library to use a Bosch Sensortec BMP085 sensor





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 * Copyright (c) 2010 Hiroshi Suga





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 * Released under the MIT License: http://mbed.org/license/mit





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 */





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#include "mbed.h"





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#include "BMP085.h"





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#define WEATHER_BMP085 0xee





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#define xpow(x, y) ((long)1 << y)





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BMP085::BMP085 (PinName p_sda, PinName p_scl, BMP085_oss p_oss) : i2c(p_sda, p_scl) {





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    init(p_oss);





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}





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BMP085::BMP085 (I2C& p_i2c, BMP085_oss p_oss) : i2c(p_i2c) { 





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    init(p_oss);





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}





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float BMP085::get_temperature() {





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    return temperature;





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}





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float BMP085::get_pressure() {





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    return pressure;





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}





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void BMP085::update () {





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    long t, p, ut, up, x1, x2, x3, b3, b5, b6;





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    unsigned long b4, b7;





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    twi_writechar(WEATHER_BMP085, 0xf4, 0x2e);





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    wait(0.01);





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    ut = twi_readshort(WEATHER_BMP085, 0xf6);





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    twi_writechar(WEATHER_BMP085, 0xf4, 0x34 | (oss << 6));





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    wait(0.05);





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    up = twi_readlong(WEATHER_BMP085, 0xf6) >> (8 - oss);





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    x1 = (ut - ac6) * ac5 / xpow(2, 15);





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    x2 = (long)mc * xpow(2, 11) / (x1 + md);





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    b5 = x1 + x2;





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    t = (b5 + 8) / xpow(2, 4);





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    temperature = (float)t / 10.0;





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    b6 = b5 - 4000;





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    x1 = (b2 * (b6 * b6 / xpow(2, 12))) / xpow(2, 11);





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    x2 = ac2 * b6 / xpow(2, 11);





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    x3 = x1 + x2;





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    b3 = ((((unsigned long)ac1 * 4 + x3) << oss) + 2) / 4;





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    x1 = ac3 * b6 / xpow(2, 13);





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    x2 = (b1 * (b6 * b6 / xpow(2, 12))) / xpow(2, 16);





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    x3 = ((x1 + x2) + 2) / xpow(2, 2);





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    b4 = ac4 * (unsigned long)(x3 + 32768) / xpow(2, 15);





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    b7 = ((unsigned long)up - b3) * (50000 >> oss);





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    if (b7 < (unsigned long)0x80000000) {





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        p = (b7 * 2) / b4;





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    } else {





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        p = (b7 / b4) * 2;





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    }





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    x1 = (p / xpow(2, 8)) * (p / xpow(2, 8));





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    x1 = (x1 * 3038) / xpow(2, 16);





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    x2 = (-7357 * p) / xpow(2, 16);





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    p = p + (x1 + x2 + 3791) / xpow(2, 4);





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    pressure = (float)p / 100.0;





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}





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void BMP085::init (BMP085_oss p_oss) {





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    ac1 = twi_readshort(WEATHER_BMP085, 0xaa);





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    ac2 = twi_readshort(WEATHER_BMP085, 0xac);





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    ac3 = twi_readshort(WEATHER_BMP085, 0xae);





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    ac4 = twi_readshort(WEATHER_BMP085, 0xb0);





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    ac5 = twi_readshort(WEATHER_BMP085, 0xb2);





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    ac6 = twi_readshort(WEATHER_BMP085, 0xb4);





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    b1 = twi_readshort(WEATHER_BMP085, 0xb6);





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    b2 = twi_readshort(WEATHER_BMP085, 0xb8);





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    mb = twi_readshort(WEATHER_BMP085, 0xba);





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    mc = twi_readshort(WEATHER_BMP085, 0xbc);





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    md = twi_readshort(WEATHER_BMP085, 0xbe);





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    oss = p_oss;





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}





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unsigned short BMP085::twi_readshort (int id, int addr) {





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    unsigned short i;





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    i2c.start();





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    i2c.write(id);





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    i2c.write(addr);





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    i2c.start();





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    i2c.write(id | 1);





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    i = i2c.read(1) << 8;





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    i |= i2c.read(0);





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    i2c.stop();





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    return i;





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}





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unsigned long BMP085::twi_readlong (int id, int addr) {





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    unsigned long i;





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    i2c.start();





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    i2c.write(id);





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    i2c.write(addr);





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    i2c.start();





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    i2c.write(id | 1);





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    i = i2c.read(1) << 16;





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    i |= i2c.read(1) << 8;





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    i |= i2c.read(0);





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    i2c.stop();





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    return i;





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}





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void BMP085::twi_writechar (int id, int addr, int dat) {





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    i2c.start();





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    i2c.write(id);





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    i2c.write(addr);





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    i2c.write(dat);





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    i2c.stop();





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}