Added htu21d.h, htu21d.c and main.c, temperature test OK

htu21d.c

@@ -0,0 +1,34 @@
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <linux/i2c-dev.h>
+#include <i2c/smbus.h>
+#include <stdio.h>
+
+#include "htu21d.h"
+
+// i2cReset
+int i2cReset(int fd){
+	if(ioctl(fd, I2C_SLAVE, ADDR)<0){
+		perror("Failed to open the I2C bus: reset\n");
+		return -1;
+	}
+	i2c_smbus_write_byte(fd, RESET);
+	return 0;
+}
+
+// get temp
+int getTemp(int fd, double *temp){
+	char buffer[3];
+	__s32 response = i2c_smbus_read_i2c_block_data(fd, TEMP, 3, buffer);
+	if(response<0){
+		perror("Failed to read temperature from sensor \n");
+		return -1;
+	}
+	*temp = -46.85+175.72*(buffer[0]*256+buffer[1])/65536;
+	return 0;
+}
+
+// get humidity
+int getHum(int fd, double *humidity){
+	return 0;
+}

htu21d.h

@@ -12,8 +12,10 @@
 #define RESET 0xFE
 
 // prototype functions:
+int i2cReset(int fs);
+
 int getTemp(int fd, double *temp);
 
 int getHum(int fd, double *hum);
 
-#endif // HTU21D_H
+#endif // HTUD_H

main.c

@@ -0,0 +1,30 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+
+#include "htu21d.h"
+
+int main(int argc, char *argv[]){
+	int fd;
+	int status;
+	double temperature;
+
+	char path[20];
+
+	snprintf(path, sizeof(path), "/dev/i2c-%d", 1);
+	fd = open(path, O_RDWR);
+	if(fd<0){
+		perror("Unable to access the i2c bus path\n");
+		return -1;
+	}
+	i2cReset(fd);
+	status = getTemp(fd, &temperature);
+	if(status<0){
+		perror("Unable to get temperature \n");
+		return -1;
+	}
+	printf("%5.2f C\n", temperature);
+	return 0;
+}
+