Reading huge amount of data throught i2c - c

Question

I am trying to receive huge amount of data throught i2c. Here is my code. The main problem is that it takes more than 2 seconds when i need to let it be done in less than 0.5 sec. Here is the device: https://www.st.com/resource/en/datasheet/lsm6ds33.pdf
image with i2c interface
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#include <time.h>
#include <sys/time.h>
#include <fcntl.h>
#include <stdint.h>
#include <stddef.h>
#define FIFO_DATA_OUT_L 0x3E
#define FIFO_DATA_OUT_H 0X3F
struct timeval stop, start;
int main()
{
uint8_t addressL = FIFO_DATA_OUT_L;
uint8_t addressH = FIFO_DATA_OUT_H;
uint8_t resultL;
uint8_t resultH;
int16_t result;
gettimeofday(&start,NULL);
int fd;
if ((fd = open("/dev/i2c-0",O_RDWR))< 0)
{
perror("failed to connect to i2c");
exit(0);
}
ioctl(fd,I2C_SLAVE,0x6b);// Setting slave address
long i;
for (i=0; i< 2499; i++)
{
write(fd,&addressL,1);
read(fd,&resultL,1);
write(fd,&addressH,1);
read(fd,&resultH,1);
result = (resultH << 8) | resultL;
}
gettimeofday(&stop,NULL);
printf("Time elapsed: %d \n",stop.tv_sec-start.tv_sec);
return;
}
I am wondering if there is some possibility to make things faster. Cheers.

Answer 1

I think your FIFO size is 2 Byte then you can write/read 2 Byte each time instead of 1.
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#include <time.h>
#include <sys/time.h>
#include <fcntl.h>
#include <stdint.h>
#include <stddef.h>
#define FIFO_DATA_OUT_L 0x3E
#define FIFO_DATA_OUT_H 0X3F
struct timeval stop, start;
int main()
{
uint8_t addressL = FIFO_DATA_OUT_L;
uint8_t addressH = FIFO_DATA_OUT_H;
uint16_t result;
gettimeofday(&start,NULL);
int fd;
if ((fd = open("/dev/i2c-0",O_RDWR))< 0)
{
perror("failed to connect to i2c");
exit(0);
}
ioctl(fd,I2C_SLAVE,0x6b);// Setting slave address
long i;
for (i=0; i< 1250; i++)
{
write(fd,&addressL,2);
read(fd,&result,2);
}
gettimeofday(&stop,NULL);
printf("Time elapsed: %d \n",stop.tv_sec-start.tv_sec);
return;
}