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50 lines
1.2 KiB
C
50 lines
1.2 KiB
C
#include <stdlib.h>
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#include <stdio.h> //to print error
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#include <unistd.h> //header file for standard I2c send and receive commands
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#include <sys/ioctl.h> //setup I2c devices
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#include <linux/i2c-dev.h> //definitions and structures
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#include <i2c/smbus.h> //smbus commands
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#include "HTU21D_H.h"
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//Declarations of functions
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// Temperature:
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int get_temp(int fd, double *temp){
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reset_sensor(fd);
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char buffer[3];
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__s32 res = i2c_smbus_read_i2c_block_data(fd, HTU21D_TEMP, sizeof(buffer), buffer);
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if (res < 0){
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perror("Error -1: Failed to read from the device");
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return -1;
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}
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*temp = -46.85+175.72*(buffer[0]*256+buffer[1])/65536.0;
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return 0;
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}
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// Humidity
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//int get_hum(int fd, double *hum);
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int get_hum(int fd, double *hum){
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reset_sensor(fd);
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char buffer[3];
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__s32 res = i2c_smbus_read_i2c_block_data(fd, HTU21D_HUM, sizeof(buffer), buffer);
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if ( res < 0 ){
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perror("Error -3: Failed to read humidity ");
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return -1;
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}
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*hum = -6+125*(buffer[0]*256+buffer[1])/65536.0;
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return 0;
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}
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// Reset Sensor
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int reset_sensor(int fd){
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if(0 > ioctl(fd, I2C_SLAVE, HTU21D_ADDR)){
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perror("Error -2: Failed to reset");
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return -2;
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}
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i2c_smbus_write_byte(fd, HTU21D_RESET);
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return 0;
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}
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