Pressure Sensor

Dependencies:   mbed-src

Fork of bmp085_lib by Suga koubou

Files at this revision

API Documentation at this revision

Comitter:
okini3939
Date:
Mon Sep 27 15:55:35 2010 +0000
Child:
1:1d88eb9f5bbd
Commit message:

Changed in this revision

BMP085/.meta Show annotated file Show diff for this revision Revisions of this file
BMP085/BMP085.cpp Show annotated file Show diff for this revision Revisions of this file
BMP085/BMP085.h Show annotated file Show diff for this revision Revisions of this file
main.cpp Show annotated file Show diff for this revision Revisions of this file
mbed.bld Show annotated file Show diff for this revision Revisions of this file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BMP085/.meta	Mon Sep 27 15:55:35 2010 +0000
@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+<root>
+  <global/>
+  <data>
+    <created_ts>1284991866</created_ts>
+    <last_mod_ts>1284991866</last_mod_ts>
+    <is_archive>0</is_archive>
+    <is_published>0</is_published>
+    <is_svn>0</is_svn>
+    <is_module>0</is_module>
+    <is_lib>1</is_lib>
+  </data>
+</root>
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BMP085/BMP085.cpp	Mon Sep 27 15:55:35 2010 +0000
@@ -0,0 +1,133 @@
+/*
+ * mbed library to use a Bosch Sensortec BMP085 sensor
+ * Copyright (c) 2010 Hiroshi Suga
+ * Released under the MIT License: http://mbed.org/license/mit
+ */
+
+#include "mbed.h"
+#include "BMP085.h"
+
+#define WEATHER_BMP085 0xee
+#define xpow(x, y) ((long)1 << y)
+
+
+BMP085::BMP085 (PinName p_sda, PinName p_scl, BMP085_oss p_oss) : i2c(p_sda, p_scl) {
+    init(p_oss);
+}
+
+BMP085::BMP085 (I2C& p_i2c, BMP085_oss p_oss) : i2c(p_i2c) { 
+    init(p_oss);
+}
+
+float BMP085::get_temperature() {
+    return temperature;
+}
+
+float BMP085::get_pressure() {
+    return pressure;
+}
+
+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) {
+
+    i2c.start();
+    i2c.write(id);
+    i2c.write(addr);
+
+    i2c.start();
+    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;
+}
+
+char BMP085::twi_writechar (int id, int addr, int dat) {
+
+    i2c.start();
+    i2c.write(id);
+    i2c.write(addr);
+    i2c.write(dat);
+    i2c.stop();
+
+    return 0;
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BMP085/BMP085.h	Mon Sep 27 15:55:35 2010 +0000
@@ -0,0 +1,44 @@
+/*
+ * mbed library to use a Bosch Sensortec BMP085 sensor
+ * Copyright (c) 2010 Hiroshi Suga
+ * Released under the MIT License: http://mbed.org/license/mit
+ */
+ 
+#ifndef BMP085_H
+#define BMP085_H
+
+#include "mbed.h"
+
+enum BMP085_oss {
+    BMP085_oss1 = 0,
+    BMP085_oss2 = 1,
+    BMP085_oss4 = 2,
+    BMP085_oss8 = 3
+};
+
+class BMP085 : public Base {
+public:
+    BMP085(PinName p_sda, PinName p_scl, BMP085_oss p_oss = BMP085_oss1);
+    BMP085(I2C& p_i2c, BMP085_oss p_oss = BMP085_oss1);
+
+    float get_temperature();
+    float get_pressure();
+    void update();
+
+protected:
+    void init(BMP085_oss);
+    unsigned short twi_readshort (int, int);
+    unsigned long twi_readlong (int, int);
+    char twi_writechar (int, int, int);
+
+    I2C i2c;
+    float temperature;
+    float pressure;
+
+private:
+
+    short ac1, ac2, ac3, b1, b2, mb, mc, md, oss;
+    unsigned short ac4, ac5, ac6;
+};
+
+#endif
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Sep 27 15:55:35 2010 +0000
@@ -0,0 +1,19 @@
+#include "mbed.h"
+#include "BMP085.h"
+
+BMP085 bmp085(p9, p10);
+
+DigitalOut myled(LED1);
+Serial pc(USBTX, USBRX);
+
+int main() {
+    while(1) {
+        myled = 1;
+
+        bmp085.update();
+        pc.printf("p:%6.2f hPa / t:%6.2f C\n", bmp085.get_pressure(), bmp085.get_temperature());
+
+        myled = 0;
+        wait(3);
+    }
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Mon Sep 27 15:55:35 2010 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/e2ac27c8e93e