José Claudio / Mbed 2 deprecated ReadingPress_BMP085

Bosh pressure sensor

Dependencies:   mbed

Fork of BMP085 by Suga koubou

BMP085.cpp@2:dee533027e61, 2013-06-12 (annotated)

Committer:
jose_claudiojr
Date:
Wed Jun 12 13:10:12 2013 +0000
Revision:
2:dee533027e61
Parent:
1:80e4c62baf09 
Bosh pressure sensor

Who changed what in which revision?

UserRevisionLine numberNew 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 1:80e4c62baf09 7 /** @file BMP085.cpp
okini3939 1:80e4c62baf09 8 * @brief mbed library to use a Bosch Sensortec BMP085 sensor
okini3939 1:80e4c62baf09 9 * barometric pressure sensor BMP085 (Bosch Sensortec)
okini3939 1:80e4c62baf09 10 * interface: I2C digital
okini3939 1:80e4c62baf09 11 */
okini3939 1:80e4c62baf09 12
okini3939 0:6245372b9179 13 #include "mbed.h"
okini3939 0:6245372b9179 14 #include "BMP085.h"
okini3939 0:6245372b9179 15
okini3939 0:6245372b9179 16 #define WEATHER_BMP085 0xee
okini3939 0:6245372b9179 17 #define xpow(x, y) ((long)1 << y)
okini3939 0:6245372b9179 18
okini3939 1:80e4c62baf09 19 /**
okini3939 1:80e4c62baf09 20 * @brief Initializes interface (private I2C)
okini3939 1:80e4c62baf09 21 * @param p_sda port of I2C SDA
okini3939 1:80e4c62baf09 22 * @param p_scl port of I2C SCL
okini3939 1:80e4c62baf09 23 * @param p_oss parameter of OSS
okini3939 1:80e4c62baf09 24 */
jose_claudiojr 2:dee533027e61 25 BMP085::BMP085 (PinName sda, PinName scl, BMP085_oss p_oss): i2c(sda, scl)
jose_claudiojr 2:dee533027e61 26 {
okini3939 0:6245372b9179 27 init(p_oss);
okini3939 0:6245372b9179 28 }
okini3939 0:6245372b9179 29
okini3939 1:80e4c62baf09 30 /**
okini3939 1:80e4c62baf09 31 * @brief Get temperature
okini3939 1:80e4c62baf09 32 * @return temperature (`C)
okini3939 1:80e4c62baf09 33 */
jose_claudiojr 2:dee533027e61 34 float BMP085::get_temperature()
jose_claudiojr 2:dee533027e61 35 {
okini3939 0:6245372b9179 36 return temperature;
okini3939 0:6245372b9179 37 }
okini3939 0:6245372b9179 38
okini3939 1:80e4c62baf09 39 /**
okini3939 1:80e4c62baf09 40 * @brief Get pressure
okini3939 1:80e4c62baf09 41 * @return pressure (hPa)
okini3939 1:80e4c62baf09 42 */
okini3939 0:6245372b9179 43 float BMP085::get_pressure() {
okini3939 0:6245372b9179 44 return pressure;
okini3939 0:6245372b9179 45 }
okini3939 0:6245372b9179 46
okini3939 1:80e4c62baf09 47 /**
okini3939 1:80e4c62baf09 48 * @brief Update results
okini3939 1:80e4c62baf09 49 */
okini3939 0:6245372b9179 50 void BMP085::update () {
okini3939 0:6245372b9179 51 long t, p, ut, up, x1, x2, x3, b3, b5, b6;
okini3939 0:6245372b9179 52 unsigned long b4, b7;
okini3939 0:6245372b9179 53
okini3939 0:6245372b9179 54 twi_writechar(WEATHER_BMP085, 0xf4, 0x2e);
okini3939 0:6245372b9179 55 wait(0.01);
okini3939 0:6245372b9179 56 ut = twi_readshort(WEATHER_BMP085, 0xf6);
okini3939 0:6245372b9179 57
okini3939 0:6245372b9179 58 twi_writechar(WEATHER_BMP085, 0xf4, 0x34 | (oss << 6));
okini3939 0:6245372b9179 59 wait(0.05);
okini3939 0:6245372b9179 60 up = twi_readlong(WEATHER_BMP085, 0xf6) >> (8 - oss);
okini3939 0:6245372b9179 61
okini3939 0:6245372b9179 62 x1 = (ut - ac6) * ac5 / xpow(2, 15);
okini3939 0:6245372b9179 63 x2 = (long)mc * xpow(2, 11) / (x1 + md);
okini3939 0:6245372b9179 64 b5 = x1 + x2;
okini3939 0:6245372b9179 65 t = (b5 + 8) / xpow(2, 4);
okini3939 0:6245372b9179 66 temperature = (float)t / 10.0;
okini3939 0:6245372b9179 67
okini3939 0:6245372b9179 68 b6 = b5 - 4000;
okini3939 0:6245372b9179 69 x1 = (b2 * (b6 * b6 / xpow(2, 12))) / xpow(2, 11);
okini3939 0:6245372b9179 70 x2 = ac2 * b6 / xpow(2, 11);
okini3939 0:6245372b9179 71 x3 = x1 + x2;
okini3939 0:6245372b9179 72 b3 = ((((unsigned long)ac1 * 4 + x3) << oss) + 2) / 4;
okini3939 0:6245372b9179 73 x1 = ac3 * b6 / xpow(2, 13);
okini3939 0:6245372b9179 74 x2 = (b1 * (b6 * b6 / xpow(2, 12))) / xpow(2, 16);
okini3939 0:6245372b9179 75 x3 = ((x1 + x2) + 2) / xpow(2, 2);
okini3939 0:6245372b9179 76 b4 = ac4 * (unsigned long)(x3 + 32768) / xpow(2, 15);
okini3939 0:6245372b9179 77 b7 = ((unsigned long)up - b3) * (50000 >> oss);
okini3939 0:6245372b9179 78 if (b7 < (unsigned long)0x80000000) {
okini3939 0:6245372b9179 79 p = (b7 * 2) / b4;
okini3939 0:6245372b9179 80 } else {
okini3939 0:6245372b9179 81 p = (b7 / b4) * 2;
okini3939 0:6245372b9179 82 }
okini3939 0:6245372b9179 83 x1 = (p / xpow(2, 8)) * (p / xpow(2, 8));
okini3939 0:6245372b9179 84 x1 = (x1 * 3038) / xpow(2, 16);
okini3939 0:6245372b9179 85 x2 = (-7357 * p) / xpow(2, 16);
okini3939 0:6245372b9179 86 p = p + (x1 + x2 + 3791) / xpow(2, 4);
okini3939 0:6245372b9179 87 pressure = (float)p / 100.0;
okini3939 0:6245372b9179 88 }
okini3939 0:6245372b9179 89
okini3939 0:6245372b9179 90 void BMP085::init (BMP085_oss p_oss) {
okini3939 0:6245372b9179 91 ac1 = twi_readshort(WEATHER_BMP085, 0xaa);
okini3939 0:6245372b9179 92 ac2 = twi_readshort(WEATHER_BMP085, 0xac);
okini3939 0:6245372b9179 93 ac3 = twi_readshort(WEATHER_BMP085, 0xae);
okini3939 0:6245372b9179 94 ac4 = twi_readshort(WEATHER_BMP085, 0xb0);
okini3939 0:6245372b9179 95 ac5 = twi_readshort(WEATHER_BMP085, 0xb2);
okini3939 0:6245372b9179 96 ac6 = twi_readshort(WEATHER_BMP085, 0xb4);
okini3939 0:6245372b9179 97 b1 = twi_readshort(WEATHER_BMP085, 0xb6);
okini3939 0:6245372b9179 98 b2 = twi_readshort(WEATHER_BMP085, 0xb8);
okini3939 0:6245372b9179 99 mb = twi_readshort(WEATHER_BMP085, 0xba);
okini3939 0:6245372b9179 100 mc = twi_readshort(WEATHER_BMP085, 0xbc);
okini3939 0:6245372b9179 101 md = twi_readshort(WEATHER_BMP085, 0xbe);
okini3939 0:6245372b9179 102 oss = p_oss;
okini3939 0:6245372b9179 103 }
okini3939 0:6245372b9179 104
jose_claudiojr 2:dee533027e61 105 unsigned short BMP085::twi_readshort (int id, int addr)
jose_claudiojr 2:dee533027e61 106 {
okini3939 0:6245372b9179 107 unsigned short i;
okini3939 0:6245372b9179 108
okini3939 0:6245372b9179 109 i2c.start();
okini3939 0:6245372b9179 110 i2c.write(id);
okini3939 0:6245372b9179 111 i2c.write(addr);
okini3939 0:6245372b9179 112
okini3939 0:6245372b9179 113 i2c.start();
okini3939 0:6245372b9179 114 i2c.write(id | 1);
okini3939 0:6245372b9179 115 i = i2c.read(1) << 8;
okini3939 0:6245372b9179 116 i |= i2c.read(0);
okini3939 0:6245372b9179 117 i2c.stop();
okini3939 0:6245372b9179 118
okini3939 0:6245372b9179 119 return i;
okini3939 0:6245372b9179 120 }
okini3939 0:6245372b9179 121
okini3939 0:6245372b9179 122 unsigned long BMP085::twi_readlong (int id, int addr) {
okini3939 0:6245372b9179 123 unsigned long i;
okini3939 0:6245372b9179 124
okini3939 0:6245372b9179 125 i2c.start();
okini3939 0:6245372b9179 126 i2c.write(id);
okini3939 0:6245372b9179 127 i2c.write(addr);
okini3939 0:6245372b9179 128
okini3939 0:6245372b9179 129 i2c.start();
okini3939 0:6245372b9179 130 i2c.write(id | 1);
okini3939 0:6245372b9179 131 i = i2c.read(1) << 16;
okini3939 0:6245372b9179 132 i |= i2c.read(1) << 8;
okini3939 0:6245372b9179 133 i |= i2c.read(0);
okini3939 0:6245372b9179 134 i2c.stop();
okini3939 0:6245372b9179 135
okini3939 0:6245372b9179 136 return i;
okini3939 0:6245372b9179 137 }
okini3939 0:6245372b9179 138
okini3939 0:6245372b9179 139 void BMP085::twi_writechar (int id, int addr, int dat) {
okini3939 0:6245372b9179 140
okini3939 0:6245372b9179 141 i2c.start();
okini3939 0:6245372b9179 142 i2c.write(id);
okini3939 0:6245372b9179 143 i2c.write(addr);
okini3939 0:6245372b9179 144 i2c.write(dat);
okini3939 0:6245372b9179 145 i2c.stop();
okini3939 0:6245372b9179 146 }