#include <stdio.h>
#include <fcntl.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#define DEV "/dev/i2c/0"

int main() {
    int fd;
    
    fd = open(DEV, O_RDWR);
    if (fd < 0)
        perror("open");
    
    int address=0x20;
    unsigned char buf[]="plaa";
    while (1) {
//    for (address=0; address<0x7F; address++) {
        if (ioctl(fd, I2C_SLAVE, address) < 0)
            perror("ioctl");
        if (read(fd, buf, 1) != 1) {
            perror("read");
            printf("%02x-", address);
        } else
            printf("%02x+ %02x ", address, buf[0]);
        
        //if ((address & 0x0F) == 0x0F)
            printf("\n");
//    }
    usleep(200000);
    }

    return 0;
}