BMP085 - barometric pressure sensor BMP085 http://mbed.…

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barometric pressure sensor BMP085 http://mbed.org/users/okini3939/notebook/barometric-pressure-sensor-bmp085/ http://mbed.org/users/okini3939/notebook/weatherduino-on-mbed/

Dependents: WeatherPlatform_20110408 WeatherPlatform ENVLogger WeatherStation ... more

BMP085.cpp@0:6245372b9179, 2010-10-14 (annotated)

Committer:: okini3939
Date:: Thu Oct 14 11:28:45 2010 +0000
Revision:: 0:6245372b9179
Child:: 1:80e4c62baf09

Who changed what in which revision?

User	Revision	Line number	New contents of line
okini3939	0:6245372b9179	1	/*
okini3939	0:6245372b9179	2	* mbed library to use a Bosch Sensortec BMP085 sensor
okini3939	0:6245372b9179	3	* Copyright (c) 2010 Hiroshi Suga
okini3939	0:6245372b9179	4	* Released under the MIT License: http://mbed.org/license/mit
okini3939	0:6245372b9179	5	*/
okini3939	0:6245372b9179	6
okini3939	0:6245372b9179	7	#include "mbed.h"
okini3939	0:6245372b9179	8	#include "BMP085.h"
okini3939	0:6245372b9179	9
okini3939	0:6245372b9179	10	#define WEATHER_BMP085 0xee
okini3939	0:6245372b9179	11	#define xpow(x, y) ((long)1 << y)
okini3939	0:6245372b9179	12
okini3939	0:6245372b9179	13
okini3939	0:6245372b9179	14	BMP085::BMP085 (PinName p_sda, PinName p_scl, BMP085_oss p_oss) : i2c(p_sda, p_scl) {
okini3939	0:6245372b9179	15	init(p_oss);
okini3939	0:6245372b9179	16	}
okini3939	0:6245372b9179	17
okini3939	0:6245372b9179	18	BMP085::BMP085 (I2C& p_i2c, BMP085_oss p_oss) : i2c(p_i2c) {
okini3939	0:6245372b9179	19	init(p_oss);
okini3939	0:6245372b9179	20	}
okini3939	0:6245372b9179	21
okini3939	0:6245372b9179	22	float BMP085::get_temperature() {
okini3939	0:6245372b9179	23	return temperature;
okini3939	0:6245372b9179	24	}
okini3939	0:6245372b9179	25
okini3939	0:6245372b9179	26	float BMP085::get_pressure() {
okini3939	0:6245372b9179	27	return pressure;
okini3939	0:6245372b9179	28	}
okini3939	0:6245372b9179	29
okini3939	0:6245372b9179	30	void BMP085::update () {
okini3939	0:6245372b9179	31	long t, p, ut, up, x1, x2, x3, b3, b5, b6;
okini3939	0:6245372b9179	32	unsigned long b4, b7;
okini3939	0:6245372b9179	33
okini3939	0:6245372b9179	34	twi_writechar(WEATHER_BMP085, 0xf4, 0x2e);
okini3939	0:6245372b9179	35	wait(0.01);
okini3939	0:6245372b9179	36	ut = twi_readshort(WEATHER_BMP085, 0xf6);
okini3939	0:6245372b9179	37
okini3939	0:6245372b9179	38	twi_writechar(WEATHER_BMP085, 0xf4, 0x34 \| (oss << 6));
okini3939	0:6245372b9179	39	wait(0.05);
okini3939	0:6245372b9179	40	up = twi_readlong(WEATHER_BMP085, 0xf6) >> (8 - oss);
okini3939	0:6245372b9179	41
okini3939	0:6245372b9179	42	x1 = (ut - ac6) * ac5 / xpow(2, 15);
okini3939	0:6245372b9179	43	x2 = (long)mc * xpow(2, 11) / (x1 + md);
okini3939	0:6245372b9179	44	b5 = x1 + x2;
okini3939	0:6245372b9179	45	t = (b5 + 8) / xpow(2, 4);
okini3939	0:6245372b9179	46	temperature = (float)t / 10.0;
okini3939	0:6245372b9179	47
okini3939	0:6245372b9179	48	b6 = b5 - 4000;
okini3939	0:6245372b9179	49	x1 = (b2 * (b6 * b6 / xpow(2, 12))) / xpow(2, 11);
okini3939	0:6245372b9179	50	x2 = ac2 * b6 / xpow(2, 11);
okini3939	0:6245372b9179	51	x3 = x1 + x2;
okini3939	0:6245372b9179	52	b3 = ((((unsigned long)ac1 * 4 + x3) << oss) + 2) / 4;
okini3939	0:6245372b9179	53	x1 = ac3 * b6 / xpow(2, 13);
okini3939	0:6245372b9179	54	x2 = (b1 * (b6 * b6 / xpow(2, 12))) / xpow(2, 16);
okini3939	0:6245372b9179	55	x3 = ((x1 + x2) + 2) / xpow(2, 2);
okini3939	0:6245372b9179	56	b4 = ac4 * (unsigned long)(x3 + 32768) / xpow(2, 15);
okini3939	0:6245372b9179	57	b7 = ((unsigned long)up - b3) * (50000 >> oss);
okini3939	0:6245372b9179	58	if (b7 < (unsigned long)0x80000000) {
okini3939	0:6245372b9179	59	p = (b7 * 2) / b4;
okini3939	0:6245372b9179	60	} else {
okini3939	0:6245372b9179	61	p = (b7 / b4) * 2;
okini3939	0:6245372b9179	62	}
okini3939	0:6245372b9179	63	x1 = (p / xpow(2, 8)) * (p / xpow(2, 8));
okini3939	0:6245372b9179	64	x1 = (x1 * 3038) / xpow(2, 16);
okini3939	0:6245372b9179	65	x2 = (-7357 * p) / xpow(2, 16);
okini3939	0:6245372b9179	66	p = p + (x1 + x2 + 3791) / xpow(2, 4);
okini3939	0:6245372b9179	67	pressure = (float)p / 100.0;
okini3939	0:6245372b9179	68	}
okini3939	0:6245372b9179	69
okini3939	0:6245372b9179	70	void BMP085::init (BMP085_oss p_oss) {
okini3939	0:6245372b9179	71	ac1 = twi_readshort(WEATHER_BMP085, 0xaa);
okini3939	0:6245372b9179	72	ac2 = twi_readshort(WEATHER_BMP085, 0xac);
okini3939	0:6245372b9179	73	ac3 = twi_readshort(WEATHER_BMP085, 0xae);
okini3939	0:6245372b9179	74	ac4 = twi_readshort(WEATHER_BMP085, 0xb0);
okini3939	0:6245372b9179	75	ac5 = twi_readshort(WEATHER_BMP085, 0xb2);
okini3939	0:6245372b9179	76	ac6 = twi_readshort(WEATHER_BMP085, 0xb4);
okini3939	0:6245372b9179	77	b1 = twi_readshort(WEATHER_BMP085, 0xb6);
okini3939	0:6245372b9179	78	b2 = twi_readshort(WEATHER_BMP085, 0xb8);
okini3939	0:6245372b9179	79	mb = twi_readshort(WEATHER_BMP085, 0xba);
okini3939	0:6245372b9179	80	mc = twi_readshort(WEATHER_BMP085, 0xbc);
okini3939	0:6245372b9179	81	md = twi_readshort(WEATHER_BMP085, 0xbe);
okini3939	0:6245372b9179	82	oss = p_oss;
okini3939	0:6245372b9179	83	}
okini3939	0:6245372b9179	84
okini3939	0:6245372b9179	85	unsigned short BMP085::twi_readshort (int id, int addr) {
okini3939	0:6245372b9179	86	unsigned short i;
okini3939	0:6245372b9179	87
okini3939	0:6245372b9179	88	i2c.start();
okini3939	0:6245372b9179	89	i2c.write(id);
okini3939	0:6245372b9179	90	i2c.write(addr);
okini3939	0:6245372b9179	91
okini3939	0:6245372b9179	92	i2c.start();
okini3939	0:6245372b9179	93	i2c.write(id \| 1);
okini3939	0:6245372b9179	94	i = i2c.read(1) << 8;
okini3939	0:6245372b9179	95	i \|= i2c.read(0);
okini3939	0:6245372b9179	96	i2c.stop();
okini3939	0:6245372b9179	97
okini3939	0:6245372b9179	98	return i;
okini3939	0:6245372b9179	99	}
okini3939	0:6245372b9179	100
okini3939	0:6245372b9179	101	unsigned long BMP085::twi_readlong (int id, int addr) {
okini3939	0:6245372b9179	102	unsigned long i;
okini3939	0:6245372b9179	103
okini3939	0:6245372b9179	104	i2c.start();
okini3939	0:6245372b9179	105	i2c.write(id);
okini3939	0:6245372b9179	106	i2c.write(addr);
okini3939	0:6245372b9179	107
okini3939	0:6245372b9179	108	i2c.start();
okini3939	0:6245372b9179	109	i2c.write(id \| 1);
okini3939	0:6245372b9179	110	i = i2c.read(1) << 16;
okini3939	0:6245372b9179	111	i \|= i2c.read(1) << 8;
okini3939	0:6245372b9179	112	i \|= i2c.read(0);
okini3939	0:6245372b9179	113	i2c.stop();
okini3939	0:6245372b9179	114
okini3939	0:6245372b9179	115	return i;
okini3939	0:6245372b9179	116	}
okini3939	0:6245372b9179	117
okini3939	0:6245372b9179	118	void BMP085::twi_writechar (int id, int addr, int dat) {
okini3939	0:6245372b9179	119
okini3939	0:6245372b9179	120	i2c.start();
okini3939	0:6245372b9179	121	i2c.write(id);
okini3939	0:6245372b9179	122	i2c.write(addr);
okini3939	0:6245372b9179	123	i2c.write(dat);
okini3939	0:6245372b9179	124	i2c.stop();
okini3939	0:6245372b9179	125	}

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Type:	Library
Created:	14 Oct 2010
Imports:	1379
Forks:	4
Commits:	3
Dependents:	20
Dependencies:	0
Followers:	43

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Barometric Pressure Sensor - BMP085

Grove Barometer Sensor

BMP085.cpp@0:6245372b9179, 2010-10-14 (annotated)

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