Omar Hagrass / CANSAT_COMBINED

IMU-pressure-tempreture sensors

Dependencies:   CMSIS_DSP_401 DHT22 MPU9150_DMP QuaternionMath MODSERIAL mbed-src FATFileSystem111 SDFileSystem11 Camera_LS_Y201_CANSAT

Dependents:   combined_F

BMP085/BMP085.cpp@4:dbb8e901826d, 2015-09-09 (annotated)

Committer:
Hagrass
Date:
Wed Sep 09 14:38:04 2015 +0000
Revision:
4:dbb8e901826d
Parent:
0:5f608863559a 
cansat 3;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Hagrass 0:5f608863559a 1 /*
Hagrass 0:5f608863559a 2 * mbed library to use a Bosch Sensortec BMP085 sensor
Hagrass 0:5f608863559a 3 * Copyright (c) 2010 Hiroshi Suga
Hagrass 0:5f608863559a 4 * Released under the MIT License: http://mbed.org/license/mit
Hagrass 0:5f608863559a 5 */
Hagrass 0:5f608863559a 6
Hagrass 0:5f608863559a 7 #include "mbed.h"
Hagrass 0:5f608863559a 8 #include "BMP085.h"
Hagrass 0:5f608863559a 9
Hagrass 0:5f608863559a 10 #define WEATHER_BMP085 0xee
Hagrass 0:5f608863559a 11 #define xpow(x, y) ((long)1 << y)
Hagrass 0:5f608863559a 12 const float ALTITUDE_EXPONENT = 1/5.255;
Hagrass 0:5f608863559a 13 const float ALTITUDE_PRESSURE_REFERENCE = 100000;
Hagrass 0:5f608863559a 14 const float ALTITUDE_COEFF = 44330.0;
Hagrass 0:5f608863559a 15 float BMP085::calcAltitude(int pressure) {
Hagrass 0:5f608863559a 16 //Compute an estimate of altitude
Hagrass 0:5f608863559a 17 // see page 15 of manual
Hagrass 0:5f608863559a 18 float float_comp_pressure = (float) pressure;
Hagrass 0:5f608863559a 19 float altitude = float_comp_pressure/ALTITUDE_PRESSURE_REFERENCE;
Hagrass 0:5f608863559a 20 altitude = pow(altitude, ALTITUDE_EXPONENT);
Hagrass 0:5f608863559a 21 altitude = 1.0 - altitude;
Hagrass 0:5f608863559a 22 altitude *= ALTITUDE_COEFF;
Hagrass 0:5f608863559a 23 // formula is: altitude = 44330 * (1-pow((p/p0), 1/5.255))
Hagrass 0:5f608863559a 24 return altitude;
Hagrass 0:5f608863559a 25 }
Hagrass 0:5f608863559a 26
Hagrass 0:5f608863559a 27 BMP085::BMP085 (PinName p_sda, PinName p_scl, BMP085_oss p_oss) : i2c(p_sda, p_scl) {
Hagrass 0:5f608863559a 28 init(p_oss);
Hagrass 0:5f608863559a 29 }
Hagrass 0:5f608863559a 30
Hagrass 0:5f608863559a 31 BMP085::BMP085 (I2C& p_i2c, BMP085_oss p_oss) : i2c(p_i2c) {
Hagrass 0:5f608863559a 32 init(p_oss);
Hagrass 0:5f608863559a 33 }
Hagrass 0:5f608863559a 34
Hagrass 0:5f608863559a 35 float BMP085::get_temperature() {
Hagrass 0:5f608863559a 36 return temperature;
Hagrass 0:5f608863559a 37 }
Hagrass 0:5f608863559a 38
Hagrass 0:5f608863559a 39 float BMP085::get_pressure() {
Hagrass 0:5f608863559a 40 return pressure;
Hagrass 0:5f608863559a 41
Hagrass 0:5f608863559a 42 }
Hagrass 0:5f608863559a 43
Hagrass 0:5f608863559a 44 void BMP085::update () {
Hagrass 0:5f608863559a 45 long t, p, ut, up, x1, x2, x3, b3, b5, b6;
Hagrass 0:5f608863559a 46 unsigned long b4, b7;
Hagrass 0:5f608863559a 47
Hagrass 0:5f608863559a 48 twi_writechar(WEATHER_BMP085, 0xf4, 0x2e);
Hagrass 0:5f608863559a 49 wait(0.01);
Hagrass 0:5f608863559a 50 ut = twi_readshort(WEATHER_BMP085, 0xf6);
Hagrass 0:5f608863559a 51
Hagrass 0:5f608863559a 52 twi_writechar(WEATHER_BMP085, 0xf4, 0x34 | (oss << 6));
Hagrass 0:5f608863559a 53 wait(0.05);
Hagrass 0:5f608863559a 54 up = twi_readlong(WEATHER_BMP085, 0xf6) >> (8 - oss);
Hagrass 0:5f608863559a 55
Hagrass 0:5f608863559a 56 x1 = (ut - ac6) * ac5 / xpow(2, 15);
Hagrass 0:5f608863559a 57 x2 = (long)mc * xpow(2, 11) / (x1 + md);
Hagrass 0:5f608863559a 58 b5 = x1 + x2;
Hagrass 0:5f608863559a 59 t = (b5 + 8) / xpow(2, 4);
Hagrass 0:5f608863559a 60 temperature = (float)t / 10.0;
Hagrass 0:5f608863559a 61
Hagrass 0:5f608863559a 62 b6 = b5 - 4000;
Hagrass 0:5f608863559a 63 x1 = (b2 * (b6 * b6 / xpow(2, 12))) / xpow(2, 11);
Hagrass 0:5f608863559a 64 x2 = ac2 * b6 / xpow(2, 11);
Hagrass 0:5f608863559a 65 x3 = x1 + x2;
Hagrass 0:5f608863559a 66 b3 = ((((unsigned long)ac1 * 4 + x3) << oss) + 2) / 4;
Hagrass 0:5f608863559a 67 x1 = ac3 * b6 / xpow(2, 13);
Hagrass 0:5f608863559a 68 x2 = (b1 * (b6 * b6 / xpow(2, 12))) / xpow(2, 16);
Hagrass 0:5f608863559a 69 x3 = ((x1 + x2) + 2) / xpow(2, 2);
Hagrass 0:5f608863559a 70 b4 = ac4 * (unsigned long)(x3 + 32768) / xpow(2, 15);
Hagrass 0:5f608863559a 71 b7 = ((unsigned long)up - b3) * (50000 >> oss);
Hagrass 0:5f608863559a 72 if (b7 < (unsigned long)0x80000000) {
Hagrass 0:5f608863559a 73 p = (b7 * 2) / b4;
Hagrass 0:5f608863559a 74 } else {
Hagrass 0:5f608863559a 75 p = (b7 / b4) * 2;
Hagrass 0:5f608863559a 76 }
Hagrass 0:5f608863559a 77 x1 = (p / xpow(2, 8)) * (p / xpow(2, 8));
Hagrass 0:5f608863559a 78 x1 = (x1 * 3038) / xpow(2, 16);
Hagrass 0:5f608863559a 79 x2 = (-7357 * p) / xpow(2, 16);
Hagrass 0:5f608863559a 80 p = p + (x1 + x2 + 3791) / xpow(2, 4);
Hagrass 0:5f608863559a 81 pressure = (float)p / 100.0;
Hagrass 0:5f608863559a 82 }
Hagrass 0:5f608863559a 83
Hagrass 0:5f608863559a 84 void BMP085::init (BMP085_oss p_oss) {
Hagrass 0:5f608863559a 85 ac1 = twi_readshort(WEATHER_BMP085, 0xaa);
Hagrass 0:5f608863559a 86 ac2 = twi_readshort(WEATHER_BMP085, 0xac);
Hagrass 0:5f608863559a 87 ac3 = twi_readshort(WEATHER_BMP085, 0xae);
Hagrass 0:5f608863559a 88 ac4 = twi_readshort(WEATHER_BMP085, 0xb0);
Hagrass 0:5f608863559a 89 ac5 = twi_readshort(WEATHER_BMP085, 0xb2);
Hagrass 0:5f608863559a 90 ac6 = twi_readshort(WEATHER_BMP085, 0xb4);
Hagrass 0:5f608863559a 91 b1 = twi_readshort(WEATHER_BMP085, 0xb6);
Hagrass 0:5f608863559a 92 b2 = twi_readshort(WEATHER_BMP085, 0xb8);
Hagrass 0:5f608863559a 93 mb = twi_readshort(WEATHER_BMP085, 0xba);
Hagrass 0:5f608863559a 94 mc = twi_readshort(WEATHER_BMP085, 0xbc);
Hagrass 0:5f608863559a 95 md = twi_readshort(WEATHER_BMP085, 0xbe);
Hagrass 0:5f608863559a 96 oss = p_oss;
Hagrass 0:5f608863559a 97 }
Hagrass 0:5f608863559a 98
Hagrass 0:5f608863559a 99 unsigned short BMP085::twi_readshort (int id, int addr) {
Hagrass 0:5f608863559a 100 unsigned short i;
Hagrass 0:5f608863559a 101
Hagrass 0:5f608863559a 102 i2c.start();
Hagrass 0:5f608863559a 103 i2c.write(id);
Hagrass 0:5f608863559a 104 i2c.write(addr);
Hagrass 0:5f608863559a 105
Hagrass 0:5f608863559a 106 i2c.start();
Hagrass 0:5f608863559a 107 i2c.write(id | 1);
Hagrass 0:5f608863559a 108 i = i2c.read(1) << 8;
Hagrass 0:5f608863559a 109 i |= i2c.read(0);
Hagrass 0:5f608863559a 110 i2c.stop();
Hagrass 0:5f608863559a 111
Hagrass 0:5f608863559a 112 return i;
Hagrass 0:5f608863559a 113 }
Hagrass 0:5f608863559a 114
Hagrass 0:5f608863559a 115 unsigned long BMP085::twi_readlong (int id, int addr) {
Hagrass 0:5f608863559a 116 unsigned long i;
Hagrass 0:5f608863559a 117
Hagrass 0:5f608863559a 118 i2c.start();
Hagrass 0:5f608863559a 119 i2c.write(id);
Hagrass 0:5f608863559a 120 i2c.write(addr);
Hagrass 0:5f608863559a 121
Hagrass 0:5f608863559a 122 i2c.start();
Hagrass 0:5f608863559a 123 i2c.write(id | 1);
Hagrass 0:5f608863559a 124 i = i2c.read(1) << 16;
Hagrass 0:5f608863559a 125 i |= i2c.read(1) << 8;
Hagrass 0:5f608863559a 126 i |= i2c.read(0);
Hagrass 0:5f608863559a 127 i2c.stop();
Hagrass 0:5f608863559a 128
Hagrass 0:5f608863559a 129 return i;
Hagrass 0:5f608863559a 130 }
Hagrass 0:5f608863559a 131
Hagrass 0:5f608863559a 132 void BMP085::twi_writechar (int id, int addr, int dat) {
Hagrass 0:5f608863559a 133
Hagrass 0:5f608863559a 134 i2c.start();
Hagrass 0:5f608863559a 135 i2c.write(id);
Hagrass 0:5f608863559a 136 i2c.write(addr);
Hagrass 0:5f608863559a 137 i2c.write(dat);
Hagrass 0:5f608863559a 138 i2c.stop();
Hagrass 0:5f608863559a 139 }