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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/
BMP085/BMP085.cpp@1:1d88eb9f5bbd, 2010-10-14 (annotated)
- Committer:
- okini3939
- Date:
- Thu Oct 14 11:27:32 2010 +0000
- Revision:
- 1:1d88eb9f5bbd
- Parent:
- 0:dbba605ca87c
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| okini3939 | 0:dbba605ca87c | 1 | /* |
| okini3939 | 0:dbba605ca87c | 2 | * mbed library to use a Bosch Sensortec BMP085 sensor |
| okini3939 | 0:dbba605ca87c | 3 | * Copyright (c) 2010 Hiroshi Suga |
| okini3939 | 0:dbba605ca87c | 4 | * Released under the MIT License: http://mbed.org/license/mit |
| okini3939 | 0:dbba605ca87c | 5 | */ |
| okini3939 | 0:dbba605ca87c | 6 | |
| okini3939 | 0:dbba605ca87c | 7 | #include "mbed.h" |
| okini3939 | 0:dbba605ca87c | 8 | #include "BMP085.h" |
| okini3939 | 0:dbba605ca87c | 9 | |
| okini3939 | 0:dbba605ca87c | 10 | #define WEATHER_BMP085 0xee |
| okini3939 | 0:dbba605ca87c | 11 | #define xpow(x, y) ((long)1 << y) |
| okini3939 | 0:dbba605ca87c | 12 | |
| okini3939 | 0:dbba605ca87c | 13 | |
| okini3939 | 0:dbba605ca87c | 14 | BMP085::BMP085 (PinName p_sda, PinName p_scl, BMP085_oss p_oss) : i2c(p_sda, p_scl) { |
| okini3939 | 0:dbba605ca87c | 15 | init(p_oss); |
| okini3939 | 0:dbba605ca87c | 16 | } |
| okini3939 | 0:dbba605ca87c | 17 | |
| okini3939 | 0:dbba605ca87c | 18 | BMP085::BMP085 (I2C& p_i2c, BMP085_oss p_oss) : i2c(p_i2c) { |
| okini3939 | 0:dbba605ca87c | 19 | init(p_oss); |
| okini3939 | 0:dbba605ca87c | 20 | } |
| okini3939 | 0:dbba605ca87c | 21 | |
| okini3939 | 0:dbba605ca87c | 22 | float BMP085::get_temperature() { |
| okini3939 | 0:dbba605ca87c | 23 | return temperature; |
| okini3939 | 0:dbba605ca87c | 24 | } |
| okini3939 | 0:dbba605ca87c | 25 | |
| okini3939 | 0:dbba605ca87c | 26 | float BMP085::get_pressure() { |
| okini3939 | 0:dbba605ca87c | 27 | return pressure; |
| okini3939 | 0:dbba605ca87c | 28 | } |
| okini3939 | 0:dbba605ca87c | 29 | |
| okini3939 | 0:dbba605ca87c | 30 | void BMP085::update () { |
| okini3939 | 0:dbba605ca87c | 31 | long t, p, ut, up, x1, x2, x3, b3, b5, b6; |
| okini3939 | 0:dbba605ca87c | 32 | unsigned long b4, b7; |
| okini3939 | 0:dbba605ca87c | 33 | |
| okini3939 | 0:dbba605ca87c | 34 | twi_writechar(WEATHER_BMP085, 0xf4, 0x2e); |
| okini3939 | 0:dbba605ca87c | 35 | wait(0.01); |
| okini3939 | 0:dbba605ca87c | 36 | ut = twi_readshort(WEATHER_BMP085, 0xf6); |
| okini3939 | 0:dbba605ca87c | 37 | |
| okini3939 | 0:dbba605ca87c | 38 | twi_writechar(WEATHER_BMP085, 0xf4, 0x34 | (oss << 6)); |
| okini3939 | 0:dbba605ca87c | 39 | wait(0.05); |
| okini3939 | 0:dbba605ca87c | 40 | up = twi_readlong(WEATHER_BMP085, 0xf6) >> (8 - oss); |
| okini3939 | 0:dbba605ca87c | 41 | |
| okini3939 | 0:dbba605ca87c | 42 | x1 = (ut - ac6) * ac5 / xpow(2, 15); |
| okini3939 | 0:dbba605ca87c | 43 | x2 = (long)mc * xpow(2, 11) / (x1 + md); |
| okini3939 | 0:dbba605ca87c | 44 | b5 = x1 + x2; |
| okini3939 | 0:dbba605ca87c | 45 | t = (b5 + 8) / xpow(2, 4); |
| okini3939 | 0:dbba605ca87c | 46 | temperature = (float)t / 10.0; |
| okini3939 | 0:dbba605ca87c | 47 | |
| okini3939 | 0:dbba605ca87c | 48 | b6 = b5 - 4000; |
| okini3939 | 0:dbba605ca87c | 49 | x1 = (b2 * (b6 * b6 / xpow(2, 12))) / xpow(2, 11); |
| okini3939 | 0:dbba605ca87c | 50 | x2 = ac2 * b6 / xpow(2, 11); |
| okini3939 | 0:dbba605ca87c | 51 | x3 = x1 + x2; |
| okini3939 | 0:dbba605ca87c | 52 | b3 = ((((unsigned long)ac1 * 4 + x3) << oss) + 2) / 4; |
| okini3939 | 0:dbba605ca87c | 53 | x1 = ac3 * b6 / xpow(2, 13); |
| okini3939 | 0:dbba605ca87c | 54 | x2 = (b1 * (b6 * b6 / xpow(2, 12))) / xpow(2, 16); |
| okini3939 | 0:dbba605ca87c | 55 | x3 = ((x1 + x2) + 2) / xpow(2, 2); |
| okini3939 | 0:dbba605ca87c | 56 | b4 = ac4 * (unsigned long)(x3 + 32768) / xpow(2, 15); |
| okini3939 | 0:dbba605ca87c | 57 | b7 = ((unsigned long)up - b3) * (50000 >> oss); |
| okini3939 | 0:dbba605ca87c | 58 | if (b7 < (unsigned long)0x80000000) { |
| okini3939 | 0:dbba605ca87c | 59 | p = (b7 * 2) / b4; |
| okini3939 | 0:dbba605ca87c | 60 | } else { |
| okini3939 | 0:dbba605ca87c | 61 | p = (b7 / b4) * 2; |
| okini3939 | 0:dbba605ca87c | 62 | } |
| okini3939 | 0:dbba605ca87c | 63 | x1 = (p / xpow(2, 8)) * (p / xpow(2, 8)); |
| okini3939 | 0:dbba605ca87c | 64 | x1 = (x1 * 3038) / xpow(2, 16); |
| okini3939 | 0:dbba605ca87c | 65 | x2 = (-7357 * p) / xpow(2, 16); |
| okini3939 | 0:dbba605ca87c | 66 | p = p + (x1 + x2 + 3791) / xpow(2, 4); |
| okini3939 | 0:dbba605ca87c | 67 | pressure = (float)p / 100.0; |
| okini3939 | 0:dbba605ca87c | 68 | } |
| okini3939 | 0:dbba605ca87c | 69 | |
| okini3939 | 0:dbba605ca87c | 70 | void BMP085::init (BMP085_oss p_oss) { |
| okini3939 | 0:dbba605ca87c | 71 | ac1 = twi_readshort(WEATHER_BMP085, 0xaa); |
| okini3939 | 0:dbba605ca87c | 72 | ac2 = twi_readshort(WEATHER_BMP085, 0xac); |
| okini3939 | 0:dbba605ca87c | 73 | ac3 = twi_readshort(WEATHER_BMP085, 0xae); |
| okini3939 | 0:dbba605ca87c | 74 | ac4 = twi_readshort(WEATHER_BMP085, 0xb0); |
| okini3939 | 0:dbba605ca87c | 75 | ac5 = twi_readshort(WEATHER_BMP085, 0xb2); |
| okini3939 | 0:dbba605ca87c | 76 | ac6 = twi_readshort(WEATHER_BMP085, 0xb4); |
| okini3939 | 0:dbba605ca87c | 77 | b1 = twi_readshort(WEATHER_BMP085, 0xb6); |
| okini3939 | 0:dbba605ca87c | 78 | b2 = twi_readshort(WEATHER_BMP085, 0xb8); |
| okini3939 | 0:dbba605ca87c | 79 | mb = twi_readshort(WEATHER_BMP085, 0xba); |
| okini3939 | 0:dbba605ca87c | 80 | mc = twi_readshort(WEATHER_BMP085, 0xbc); |
| okini3939 | 0:dbba605ca87c | 81 | md = twi_readshort(WEATHER_BMP085, 0xbe); |
| okini3939 | 0:dbba605ca87c | 82 | oss = p_oss; |
| okini3939 | 0:dbba605ca87c | 83 | } |
| okini3939 | 0:dbba605ca87c | 84 | |
| okini3939 | 0:dbba605ca87c | 85 | unsigned short BMP085::twi_readshort (int id, int addr) { |
| okini3939 | 0:dbba605ca87c | 86 | unsigned short i; |
| okini3939 | 0:dbba605ca87c | 87 | |
| okini3939 | 0:dbba605ca87c | 88 | i2c.start(); |
| okini3939 | 0:dbba605ca87c | 89 | i2c.write(id); |
| okini3939 | 0:dbba605ca87c | 90 | i2c.write(addr); |
| okini3939 | 0:dbba605ca87c | 91 | |
| okini3939 | 0:dbba605ca87c | 92 | i2c.start(); |
| okini3939 | 0:dbba605ca87c | 93 | i2c.write(id | 1); |
| okini3939 | 0:dbba605ca87c | 94 | i = i2c.read(1) << 8; |
| okini3939 | 0:dbba605ca87c | 95 | i |= i2c.read(0); |
| okini3939 | 0:dbba605ca87c | 96 | i2c.stop(); |
| okini3939 | 0:dbba605ca87c | 97 | |
| okini3939 | 0:dbba605ca87c | 98 | return i; |
| okini3939 | 0:dbba605ca87c | 99 | } |
| okini3939 | 0:dbba605ca87c | 100 | |
| okini3939 | 0:dbba605ca87c | 101 | unsigned long BMP085::twi_readlong (int id, int addr) { |
| okini3939 | 0:dbba605ca87c | 102 | unsigned long i; |
| okini3939 | 0:dbba605ca87c | 103 | |
| okini3939 | 0:dbba605ca87c | 104 | i2c.start(); |
| okini3939 | 0:dbba605ca87c | 105 | i2c.write(id); |
| okini3939 | 0:dbba605ca87c | 106 | i2c.write(addr); |
| okini3939 | 0:dbba605ca87c | 107 | |
| okini3939 | 0:dbba605ca87c | 108 | i2c.start(); |
| okini3939 | 0:dbba605ca87c | 109 | i2c.write(id | 1); |
| okini3939 | 0:dbba605ca87c | 110 | i = i2c.read(1) << 16; |
| okini3939 | 0:dbba605ca87c | 111 | i |= i2c.read(1) << 8; |
| okini3939 | 0:dbba605ca87c | 112 | i |= i2c.read(0); |
| okini3939 | 0:dbba605ca87c | 113 | i2c.stop(); |
| okini3939 | 0:dbba605ca87c | 114 | |
| okini3939 | 0:dbba605ca87c | 115 | return i; |
| okini3939 | 0:dbba605ca87c | 116 | } |
| okini3939 | 0:dbba605ca87c | 117 | |
| okini3939 | 1:1d88eb9f5bbd | 118 | void BMP085::twi_writechar (int id, int addr, int dat) { |
| okini3939 | 0:dbba605ca87c | 119 | |
| okini3939 | 0:dbba605ca87c | 120 | i2c.start(); |
| okini3939 | 0:dbba605ca87c | 121 | i2c.write(id); |
| okini3939 | 0:dbba605ca87c | 122 | i2c.write(addr); |
| okini3939 | 0:dbba605ca87c | 123 | i2c.write(dat); |
| okini3939 | 0:dbba605ca87c | 124 | i2c.stop(); |
| okini3939 | 0:dbba605ca87c | 125 | } |