Raspberry drives Stepper

# 5 wire Steppermotor  with driver uln2003 and i2c portmultiplexer pcf8574
# compile with 
# gcc -o go_step  go_step.c
# pcf8574 p0 -> uln2003 in1 and so on.

#include <stdio.h>
#include <stdlib.h>
#include <linux/i2c-dev.h>
#include <linux/i2c.h>
#include <fcntl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>


char Device[] = "/dev/i2c-1";
int fd;
int res;
int  address = 0x20;
char Buffer[1];




int main(int argc, char** argv)                                                // Programmstart
{
int i;
int t;
unsigned char ca[8];

ca[0]= 0x08;
ca[1]= 0x12;
ca[2]= 0x04;
ca[3]= 0x06;
ca[4]= 0x02;
ca[5]= 0x03;
ca[6]= 0x01;
ca[7]= 0x09;


        fd = open(Device, O_RDWR);

        if (ioctl(fd, I2C_SLAVE, address) < 0)                                 // Set the port options and set the address of the device we wish to speak to
        {
                printf("Unable to get bus access to talk to slave\n");
                exit(1);
        }

        //res = write(fd, argv[1], 1);
       for(t=0; t<3600;t++)
      {
       i=0;
       while ( i<8)
       {
       //     printf("%d \n", i);
       //sprintf(Buffer,"%d",i);
       Buffer[0]=ca[i]; 
        res = write(fd, Buffer, 1);
        i++;
        usleep(6000);
        //not less then 1500
       }
       }
        close(fd);
        return 0;
}