José Claudio
/
ReadingPress_BMP085
Bosh pressure sensor
Fork of BMP085 by
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?
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 | */ |
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 | } |