-
Notifications
You must be signed in to change notification settings - Fork 19
/
bmp085.c
210 lines (184 loc) · 5.76 KB
/
bmp085.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
/*
bmp085 lib 0x01
copyright (c) Davide Gironi, 2012
Released under GPLv3.
Please refer to LICENSE file for licensing information.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <avr/io.h>
#include <util/delay.h>
#include "bmp085.h"
//variables
static int bmp085_regac1, bmp085_regac2, bmp085_regac3, bmp085_regb1, bmp085_regb2, bmp085_regmb, bmp085_regmc, bmp085_regmd;
static unsigned int bmp085_regac4, bmp085_regac5, bmp085_regac6;
static long bmp085_rawtemperature, bmp085_rawpressure;
//path to i2c fleury lib
#include BMP085_I2CFLEURYPATH
/*
* i2c write
*/
void bmp085_writemem(uint8_t reg, uint8_t value) {
i2c_start_wait(BMP085_ADDR | I2C_WRITE);
i2c_write(reg);
i2c_write(value);
i2c_stop();
}
/*
* i2c read
*/
void bmp085_readmem(uint8_t reg, uint8_t buff[], uint8_t bytes) {
uint8_t i =0;
i2c_start_wait(BMP085_ADDR | I2C_WRITE);
i2c_write(reg);
i2c_rep_start(BMP085_ADDR | I2C_READ);
for(i=0; i<bytes; i++) {
if(i==bytes-1)
buff[i] = i2c_readNak();
else
buff[i] = i2c_readAck();
}
i2c_stop();
}
#if BMP085_FILTERPRESSURE == 1
#define BMP085_AVARAGECOEF 21
static long k[BMP085_AVARAGECOEF];
long bmp085_avaragefilter(long input) {
uint8_t i=0;
long sum=0;
for (i=0; i<BMP085_AVARAGECOEF; i++) {
k[i] = k[i+1];
}
k[BMP085_AVARAGECOEF-1] = input;
for (i=0; i<BMP085_AVARAGECOEF; i++) {
sum += k[i];
}
return (sum /BMP085_AVARAGECOEF) ;
}
#endif
/*
* read calibration registers
*/
void bmp085_getcalibration(void) {
uint8_t buff[2];
memset(buff, 0, sizeof(buff));
bmp085_readmem(BMP085_REGAC1, buff, 2);
bmp085_regac1 = ((int)buff[0] <<8 | ((int)buff[1]));
bmp085_readmem(BMP085_REGAC2, buff, 2);
bmp085_regac2 = ((int)buff[0] <<8 | ((int)buff[1]));
bmp085_readmem(BMP085_REGAC3, buff, 2);
bmp085_regac3 = ((int)buff[0] <<8 | ((int)buff[1]));
bmp085_readmem(BMP085_REGAC4, buff, 2);
bmp085_regac4 = ((unsigned int)buff[0] <<8 | ((unsigned int)buff[1]));
bmp085_readmem(BMP085_REGAC5, buff, 2);
bmp085_regac5 = ((unsigned int)buff[0] <<8 | ((unsigned int)buff[1]));
bmp085_readmem(BMP085_REGAC6, buff, 2);
bmp085_regac6 = ((unsigned int)buff[0] <<8 | ((unsigned int)buff[1]));
bmp085_readmem(BMP085_REGB1, buff, 2);
bmp085_regb1 = ((int)buff[0] <<8 | ((int)buff[1]));
bmp085_readmem(BMP085_REGB2, buff, 2);
bmp085_regb2 = ((int)buff[0] <<8 | ((int)buff[1]));
bmp085_readmem(BMP085_REGMB, buff, 2);
bmp085_regmb = ((int)buff[0] <<8 | ((int)buff[1]));
bmp085_readmem(BMP085_REGMC, buff, 2);
bmp085_regmc = ((int)buff[0] <<8 | ((int)buff[1]));
bmp085_readmem(BMP085_REGMD, buff, 2);
bmp085_regmd = ((int)buff[0] <<8 | ((int)buff[1]));
}
/*
* get raw temperature as read by registers, and do some calculation to convert it
*/
void bmp085_getrawtemperature(void) {
uint8_t buff[2];
memset(buff, 0, sizeof(buff));
long ut,x1,x2;
//read raw temperature
bmp085_writemem(BMP085_REGCONTROL, BMP085_REGREADTEMPERATURE);
_delay_ms(5); // min. 4.5ms read Temp delay
bmp085_readmem(BMP085_REGCONTROLOUTPUT, buff, 2);
ut = ((long)buff[0] << 8 | ((long)buff[1])); //uncompensated temperature value
//calculate raw temperature
x1 = ((long)ut - bmp085_regac6) * bmp085_regac5 >> 15;
x2 = ((long)bmp085_regmc << 11) / (x1 + bmp085_regmd);
bmp085_rawtemperature = x1 + x2;
}
/*
* get raw pressure as read by registers, and do some calculation to convert it
*/
void bmp085_getrawpressure(void) {
uint8_t buff[3];
memset(buff, 0, sizeof(buff));
long up,x1,x2,x3,b3,b6,p;
unsigned long b4,b7;
#if BMP085_AUTOUPDATETEMP == 1
bmp085_getrawtemperature();
#endif
//read raw pressure
bmp085_writemem(BMP085_REGCONTROL, BMP085_REGREADPRESSURE+(BMP085_MODE << 6));
_delay_ms(2 + (3<<BMP085_MODE));
bmp085_readmem(BMP085_REGCONTROLOUTPUT, buff, 3);
up = ((((long)buff[0] <<16) | ((long)buff[1] <<8) | ((long)buff[2])) >> (8-BMP085_MODE)); // uncompensated pressure value
//calculate raw pressure
b6 = bmp085_rawtemperature - 4000;
x1 = (bmp085_regb2* (b6 * b6) >> 12) >> 11;
x2 = (bmp085_regac2 * b6) >> 11;
x3 = x1 + x2;
b3 = (((((long)bmp085_regac1) * 4 + x3) << BMP085_MODE) + 2) >> 2;
x1 = (bmp085_regac3 * b6) >> 13;
x2 = (bmp085_regb1 * ((b6 * b6) >> 12)) >> 16;
x3 = ((x1 + x2) + 2) >> 2;
b4 = (bmp085_regac4 * (uint32_t)(x3 + 32768)) >> 15;
b7 = ((uint32_t)up - b3) * (50000 >> BMP085_MODE);
p = b7 < 0x80000000 ? (b7 << 1) / b4 : (b7 / b4) << 1;
x1 = (p >> 8) * (p >> 8);
x1 = (x1 * 3038) >> 16;
x2 = (-7357 * p) >> 16;
bmp085_rawpressure = p + ((x1 + x2 + 3791) >> 4);
#if BMP085_FILTERPRESSURE == 1
bmp085_rawpressure = bmp085_avaragefilter(bmp085_rawpressure);
#endif
}
/*
* get celsius temperature
*/
int16_t bmp085_gettemperature(void) {
bmp085_getrawtemperature();
/*long x1, x2;
x1 = ((bmp085_rawtemperature - bmp085_regac6) * bmp085_regac5) >> 15;
x2 = (bmp085_regmc << 11) / (x1 + bmp085_regmd);
return (((x1 + x2 + 8) >> 4) - 32.0f) / 1.8f;
*/
long temperature = ((bmp085_rawtemperature + 8)>>4);
temperature = temperature;
return temperature;
}
/*
* get pressure
*/
long bmp085_getpressure(void) {
bmp085_getrawpressure();
return (bmp085_rawpressure + BMP085_UNITPAOFFSET);
}
/*
* get altitude
*/
int16_t bmp085_getaltitude(void) {
bmp085_getrawpressure();
return ((1 - pow(bmp085_rawpressure/(double)101325, 0.1903 )) / 0.0000225577) + BMP085_UNITMOFFSET;
}
/*
* init bmp085
*/
void bmp085_init(void) {
bmp085_getcalibration(); //get calibration data
bmp085_getrawtemperature(); //update raw temperature, at least the first time
#if BMP085_FILTERPRESSURE == 1
//initialize the avarage filter
uint8_t i=0;
for (i=0; i<BMP085_AVARAGECOEF; i++) {
bmp085_getrawpressure();
}
#endif
}