/
main.c
177 lines (147 loc) · 5.53 KB
/
main.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
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <limits.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/i2c-dev.h>
#include <linux/i2c.h>
static const char* dev_name = "/dev/i2c-1";
uint8_t dev_addr = 0x76;
int fd;
int digT[3], digP[9], digH[6];
double t_fine;
int i2c_read(uint8_t reg_addr, uint8_t* data, uint16_t length) {
struct i2c_msg messages[] = {
{ dev_addr, 0, 1, ®_addr },
{ dev_addr, I2C_M_RD, length, data },
};
struct i2c_rdwr_ioctl_data ioctl_data = { messages, 2 };
if (ioctl(fd, I2C_RDWR, &ioctl_data) != 2) {
fprintf(stderr, "i2c_read: failed to ioctl: %s\n", strerror(errno));
return -1;
}
return 0;
}
int i2c_write(uint8_t reg_addr, const uint8_t* data, uint16_t length) {
uint8_t* buffer = (uint8_t*)malloc(length + 1);
if (buffer == NULL) {
fprintf(stderr, "i2c_write: failed to memory allocate\n");
return -1;
}
buffer[0] = reg_addr;
memcpy(&buffer[1], data, length);
struct i2c_msg message = { dev_addr, 0, length + 1, buffer };
struct i2c_rdwr_ioctl_data ioctl_data = { &message, 1 };
if (ioctl(fd, I2C_RDWR, &ioctl_data) != 1) {
fprintf(stderr, "i2c_write: failed to ioctl: %s\n", strerror(errno));
free(buffer);
return -1;
}
free(buffer);
return 0;
}
void get_calib_param() {
uint8_t calib[32] = {};
int i;
i2c_read(0x88, calib, 24);
i2c_read(0xA1, &calib[24], 1);
i2c_read(0xE1, &calib[25], 7);
digT[0] = ((calib[1] << 8) | calib[0]);
digT[1] = ((calib[3] << 8) | calib[2]);
digT[2] = ((calib[5] << 8) | calib[4]);
digP[0] = ((calib[7] << 8) | calib[6]);
digP[1] = ((calib[9] << 8) | calib[8]);
digP[2] = ((calib[11]<< 8) | calib[10]);
digP[3] = ((calib[13]<< 8) | calib[12]);
digP[4] = ((calib[15]<< 8) | calib[14]);
digP[5] = ((calib[17]<< 8) | calib[16]);
digP[6] = ((calib[19]<< 8) | calib[18]);
digP[7] = ((calib[21]<< 8) | calib[20]);
digP[8] = ((calib[23]<< 8) | calib[22]);
digH[0] = ( calib[24] );
digH[1] = ((calib[26]<< 8) | calib[25]);
digH[2] = ( calib[27] );
digH[3] = ((calib[28]<< 4) | (0x0F & calib[29]));
digH[4] = ((calib[30]<< 4) | ((calib[29] >> 4) & 0x0F));
digH[5] = ( calib[31] );
for (i = 1; i < 2; i++) if (digT[i] & 0x8000) digT[i] = (-digT[i] ^ 0xFFFF) + 1;
for (i = 1; i < 8; i++) if (digP[i] & 0x8000) digP[i] = (-digP[i] ^ 0xFFFF) + 1;
for (i = 0; i < 6; i++) if (digH[i] & 0x8000) digH[i] = (-digH[i] ^ 0xFFFF) + 1;
}
double compensate_P(uint32_t adc_P) {
double pressure = 0.0;
double v1 = (t_fine / 2.0) - 64000.0;
double v2 = (((v1 / 4.0) * (v1 / 4.0)) / 2048) * digP[5];
v2 = v2 + ((v1 * digP[4]) * 2.0);
v2 = (v2 / 4.0) + (digP[3] * 65536.0);
v1 = (((digP[2] * (((v1 / 4.0) * (v1 / 4.0)) / 8192)) / 8) + ((digP[1] * v1) / 2.0)) / 262144;
v1 = ((32768 + v1) * digP[0]) / 32768;
if (v1 == 0) return 0;
pressure = ((1048576 - adc_P) - (v2 / 4096)) * 3125;
if (pressure < 0x80000000) pressure = (pressure * 2.0) / v1;
else pressure = (pressure / v1) * 2;
v1 = (digP[8] * (((pressure / 8.0) * (pressure / 8.0)) / 8192.0)) / 4096;
v2 = ((pressure / 4.0) * digP[7]) / 8192.0;
pressure = pressure + ((v1 + v2 + digP[6]) / 16.0);
return pressure / 100;
}
double compensate_T(uint32_t adc_T) {
double v1 = (adc_T / 16384.0 - digT[0] / 1024.0) * digT[1];
double v2 = (adc_T / 131072.0 - digT[0] / 8192.0) * (adc_T / 131072.0 - digT[0] / 8192.0) * digT[2];
t_fine = v1 + v2;
double temperature = t_fine / 5120.0;
return temperature;
}
double compensate_H(uint32_t adc_H) {
double var_h = t_fine - 76800.0;
if (var_h == 0) return 0;
var_h = (adc_H - (digH[3] * 64.0 + digH[4]/16384.0 * var_h)) * (digH[1] / 65536.0 * (1.0 + digH[5] / 67108864.0 * var_h * (1.0 + digH[2] / 67108864.0 * var_h)));
if (var_h > 100.0) return 100.0;
else if (var_h < 0.0) return 0.0;
else return var_h;
}
void read_data(double *temp, double *pres, double *hum) {
uint8_t data[8] = {};
i2c_read(0xF7, data, 8);
uint32_t pres_raw = (data[0] << 12) | (data[1] << 4) | (data[2] >> 4);
uint32_t temp_raw = (data[3] << 12) | (data[4] << 4) | (data[5] >> 4);
uint32_t hum_raw = (data[6] << 8) | data[7];
*temp = compensate_T(temp_raw);
*pres = compensate_P(pres_raw);
*hum = compensate_H(hum_raw);
}
void setup() {
uint8_t osrs_t = 1; // Temperature oversampling x 1
uint8_t osrs_p = 1; // Pressure oversampling x 1
uint8_t osrs_h = 1; // Humidity oversampling x 1
uint8_t mode = 3; // Normal mode
uint8_t t_sb = 5; // Tstandby 1000ms
uint8_t filter = 0; // Filter off
uint8_t spi3w_en = 0; // 3-wire SPI Disable
uint8_t ctrl_meas_reg = (osrs_t << 5) | (osrs_p << 2) | mode;
uint8_t config_reg = (t_sb << 5) | (filter << 2) | spi3w_en;
uint8_t ctrl_hum_reg = osrs_h;
i2c_write(0xF2, &ctrl_hum_reg, 1);
i2c_write(0xF4, &ctrl_meas_reg, 1);
i2c_write(0xF5, &config_reg, 1);
}
int main() {
fd = open(dev_name, O_RDWR);
if (fd < 0) {
fprintf(stderr, "Failed to open i2c: %s\n", strerror(errno));
return INT_MIN;
}
setup();
get_calib_param();
double temp, pres, hum;
read_data(&temp, &pres, &hum);
printf("temp: %-6.2f°C\n", temp);
printf("pressure : %7.2f hPa\n", pres);
printf("hum : %6.2f %%\n", hum);
close(fd);
return 0;
}