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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@1:80e4c62baf09, 2010-12-13 (annotated)
- Committer:
- okini3939
- Date:
- Mon Dec 13 14:02:24 2010 +0000
- Revision:
- 1:80e4c62baf09
- Parent:
- 0:6245372b9179
- Child:
- 2:5e2b1f3c0a6a
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 | 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 | */ |
| okini3939 | 0:6245372b9179 | 25 | BMP085::BMP085 (PinName p_sda, PinName p_scl, BMP085_oss p_oss) : i2c(p_sda, p_scl) { |
| okini3939 | 0:6245372b9179 | 26 | init(p_oss); |
| okini3939 | 0:6245372b9179 | 27 | } |
| okini3939 | 0:6245372b9179 | 28 | |
| okini3939 | 1:80e4c62baf09 | 29 | /** |
| okini3939 | 1:80e4c62baf09 | 30 | * @brief Initializes interface (public I2C) |
| okini3939 | 1:80e4c62baf09 | 31 | * @param p_i2c instance of I2C class |
| okini3939 | 1:80e4c62baf09 | 32 | * @param p_oss parameter of OSS |
| okini3939 | 1:80e4c62baf09 | 33 | */ |
| okini3939 | 0:6245372b9179 | 34 | BMP085::BMP085 (I2C& p_i2c, BMP085_oss p_oss) : i2c(p_i2c) { |
| okini3939 | 0:6245372b9179 | 35 | init(p_oss); |
| okini3939 | 0:6245372b9179 | 36 | } |
| okini3939 | 0:6245372b9179 | 37 | |
| okini3939 | 1:80e4c62baf09 | 38 | /** |
| okini3939 | 1:80e4c62baf09 | 39 | * @brief Get temperature |
| okini3939 | 1:80e4c62baf09 | 40 | * @return temperature (`C) |
| okini3939 | 1:80e4c62baf09 | 41 | */ |
| okini3939 | 0:6245372b9179 | 42 | float BMP085::get_temperature() { |
| okini3939 | 0:6245372b9179 | 43 | return temperature; |
| okini3939 | 0:6245372b9179 | 44 | } |
| okini3939 | 0:6245372b9179 | 45 | |
| okini3939 | 1:80e4c62baf09 | 46 | /** |
| okini3939 | 1:80e4c62baf09 | 47 | * @brief Get pressure |
| okini3939 | 1:80e4c62baf09 | 48 | * @return pressure (hPa) |
| okini3939 | 1:80e4c62baf09 | 49 | */ |
| okini3939 | 0:6245372b9179 | 50 | float BMP085::get_pressure() { |
| okini3939 | 0:6245372b9179 | 51 | return pressure; |
| okini3939 | 0:6245372b9179 | 52 | } |
| okini3939 | 0:6245372b9179 | 53 | |
| okini3939 | 1:80e4c62baf09 | 54 | /** |
| okini3939 | 1:80e4c62baf09 | 55 | * @brief Update results |
| okini3939 | 1:80e4c62baf09 | 56 | */ |
| okini3939 | 0:6245372b9179 | 57 | void BMP085::update () { |
| okini3939 | 0:6245372b9179 | 58 | long t, p, ut, up, x1, x2, x3, b3, b5, b6; |
| okini3939 | 0:6245372b9179 | 59 | unsigned long b4, b7; |
| okini3939 | 0:6245372b9179 | 60 | |
| okini3939 | 0:6245372b9179 | 61 | twi_writechar(WEATHER_BMP085, 0xf4, 0x2e); |
| okini3939 | 0:6245372b9179 | 62 | wait(0.01); |
| okini3939 | 0:6245372b9179 | 63 | ut = twi_readshort(WEATHER_BMP085, 0xf6); |
| okini3939 | 0:6245372b9179 | 64 | |
| okini3939 | 0:6245372b9179 | 65 | twi_writechar(WEATHER_BMP085, 0xf4, 0x34 | (oss << 6)); |
| okini3939 | 0:6245372b9179 | 66 | wait(0.05); |
| okini3939 | 0:6245372b9179 | 67 | up = twi_readlong(WEATHER_BMP085, 0xf6) >> (8 - oss); |
| okini3939 | 0:6245372b9179 | 68 | |
| okini3939 | 0:6245372b9179 | 69 | x1 = (ut - ac6) * ac5 / xpow(2, 15); |
| okini3939 | 0:6245372b9179 | 70 | x2 = (long)mc * xpow(2, 11) / (x1 + md); |
| okini3939 | 0:6245372b9179 | 71 | b5 = x1 + x2; |
| okini3939 | 0:6245372b9179 | 72 | t = (b5 + 8) / xpow(2, 4); |
| okini3939 | 0:6245372b9179 | 73 | temperature = (float)t / 10.0; |
| okini3939 | 0:6245372b9179 | 74 | |
| okini3939 | 0:6245372b9179 | 75 | b6 = b5 - 4000; |
| okini3939 | 0:6245372b9179 | 76 | x1 = (b2 * (b6 * b6 / xpow(2, 12))) / xpow(2, 11); |
| okini3939 | 0:6245372b9179 | 77 | x2 = ac2 * b6 / xpow(2, 11); |
| okini3939 | 0:6245372b9179 | 78 | x3 = x1 + x2; |
| okini3939 | 0:6245372b9179 | 79 | b3 = ((((unsigned long)ac1 * 4 + x3) << oss) + 2) / 4; |
| okini3939 | 0:6245372b9179 | 80 | x1 = ac3 * b6 / xpow(2, 13); |
| okini3939 | 0:6245372b9179 | 81 | x2 = (b1 * (b6 * b6 / xpow(2, 12))) / xpow(2, 16); |
| okini3939 | 0:6245372b9179 | 82 | x3 = ((x1 + x2) + 2) / xpow(2, 2); |
| okini3939 | 0:6245372b9179 | 83 | b4 = ac4 * (unsigned long)(x3 + 32768) / xpow(2, 15); |
| okini3939 | 0:6245372b9179 | 84 | b7 = ((unsigned long)up - b3) * (50000 >> oss); |
| okini3939 | 0:6245372b9179 | 85 | if (b7 < (unsigned long)0x80000000) { |
| okini3939 | 0:6245372b9179 | 86 | p = (b7 * 2) / b4; |
| okini3939 | 0:6245372b9179 | 87 | } else { |
| okini3939 | 0:6245372b9179 | 88 | p = (b7 / b4) * 2; |
| okini3939 | 0:6245372b9179 | 89 | } |
| okini3939 | 0:6245372b9179 | 90 | x1 = (p / xpow(2, 8)) * (p / xpow(2, 8)); |
| okini3939 | 0:6245372b9179 | 91 | x1 = (x1 * 3038) / xpow(2, 16); |
| okini3939 | 0:6245372b9179 | 92 | x2 = (-7357 * p) / xpow(2, 16); |
| okini3939 | 0:6245372b9179 | 93 | p = p + (x1 + x2 + 3791) / xpow(2, 4); |
| okini3939 | 0:6245372b9179 | 94 | pressure = (float)p / 100.0; |
| okini3939 | 0:6245372b9179 | 95 | } |
| okini3939 | 0:6245372b9179 | 96 | |
| okini3939 | 0:6245372b9179 | 97 | void BMP085::init (BMP085_oss p_oss) { |
| okini3939 | 0:6245372b9179 | 98 | ac1 = twi_readshort(WEATHER_BMP085, 0xaa); |
| okini3939 | 0:6245372b9179 | 99 | ac2 = twi_readshort(WEATHER_BMP085, 0xac); |
| okini3939 | 0:6245372b9179 | 100 | ac3 = twi_readshort(WEATHER_BMP085, 0xae); |
| okini3939 | 0:6245372b9179 | 101 | ac4 = twi_readshort(WEATHER_BMP085, 0xb0); |
| okini3939 | 0:6245372b9179 | 102 | ac5 = twi_readshort(WEATHER_BMP085, 0xb2); |
| okini3939 | 0:6245372b9179 | 103 | ac6 = twi_readshort(WEATHER_BMP085, 0xb4); |
| okini3939 | 0:6245372b9179 | 104 | b1 = twi_readshort(WEATHER_BMP085, 0xb6); |
| okini3939 | 0:6245372b9179 | 105 | b2 = twi_readshort(WEATHER_BMP085, 0xb8); |
| okini3939 | 0:6245372b9179 | 106 | mb = twi_readshort(WEATHER_BMP085, 0xba); |
| okini3939 | 0:6245372b9179 | 107 | mc = twi_readshort(WEATHER_BMP085, 0xbc); |
| okini3939 | 0:6245372b9179 | 108 | md = twi_readshort(WEATHER_BMP085, 0xbe); |
| okini3939 | 0:6245372b9179 | 109 | oss = p_oss; |
| okini3939 | 0:6245372b9179 | 110 | } |
| okini3939 | 0:6245372b9179 | 111 | |
| okini3939 | 0:6245372b9179 | 112 | unsigned short BMP085::twi_readshort (int id, int addr) { |
| okini3939 | 0:6245372b9179 | 113 | unsigned short i; |
| okini3939 | 0:6245372b9179 | 114 | |
| okini3939 | 0:6245372b9179 | 115 | i2c.start(); |
| okini3939 | 0:6245372b9179 | 116 | i2c.write(id); |
| okini3939 | 0:6245372b9179 | 117 | i2c.write(addr); |
| okini3939 | 0:6245372b9179 | 118 | |
| okini3939 | 0:6245372b9179 | 119 | i2c.start(); |
| okini3939 | 0:6245372b9179 | 120 | i2c.write(id | 1); |
| okini3939 | 0:6245372b9179 | 121 | i = i2c.read(1) << 8; |
| okini3939 | 0:6245372b9179 | 122 | i |= i2c.read(0); |
| okini3939 | 0:6245372b9179 | 123 | i2c.stop(); |
| okini3939 | 0:6245372b9179 | 124 | |
| okini3939 | 0:6245372b9179 | 125 | return i; |
| okini3939 | 0:6245372b9179 | 126 | } |
| okini3939 | 0:6245372b9179 | 127 | |
| okini3939 | 0:6245372b9179 | 128 | unsigned long BMP085::twi_readlong (int id, int addr) { |
| okini3939 | 0:6245372b9179 | 129 | unsigned long i; |
| okini3939 | 0:6245372b9179 | 130 | |
| okini3939 | 0:6245372b9179 | 131 | i2c.start(); |
| okini3939 | 0:6245372b9179 | 132 | i2c.write(id); |
| okini3939 | 0:6245372b9179 | 133 | i2c.write(addr); |
| okini3939 | 0:6245372b9179 | 134 | |
| okini3939 | 0:6245372b9179 | 135 | i2c.start(); |
| okini3939 | 0:6245372b9179 | 136 | i2c.write(id | 1); |
| okini3939 | 0:6245372b9179 | 137 | i = i2c.read(1) << 16; |
| okini3939 | 0:6245372b9179 | 138 | i |= i2c.read(1) << 8; |
| okini3939 | 0:6245372b9179 | 139 | i |= i2c.read(0); |
| okini3939 | 0:6245372b9179 | 140 | i2c.stop(); |
| okini3939 | 0:6245372b9179 | 141 | |
| okini3939 | 0:6245372b9179 | 142 | return i; |
| okini3939 | 0:6245372b9179 | 143 | } |
| okini3939 | 0:6245372b9179 | 144 | |
| okini3939 | 0:6245372b9179 | 145 | void BMP085::twi_writechar (int id, int addr, int dat) { |
| okini3939 | 0:6245372b9179 | 146 | |
| okini3939 | 0:6245372b9179 | 147 | i2c.start(); |
| okini3939 | 0:6245372b9179 | 148 | i2c.write(id); |
| okini3939 | 0:6245372b9179 | 149 | i2c.write(addr); |
| okini3939 | 0:6245372b9179 | 150 | i2c.write(dat); |
| okini3939 | 0:6245372b9179 | 151 | i2c.stop(); |
| okini3939 | 0:6245372b9179 | 152 | } |
Barometric Pressure Sensor - BMP085
Grove Barometer Sensor