void delay(){
  for(volatile long i=0;i<100000;i++);
}
void setup(){
  volatile unsigned char *dirA;
  dirA=0X21;
  *dirA=0Xff;
  volatile unsigned char *dirB;
  dirB=0X24;
  *dirB=0Xff;
}
void loop(){
  volatile unsigned char *outA;
  outA=0X22;
  for(int i=0;i<8;i+=2){
    *outA=(1<<i)|(1<<(i+1));
    delay();
    *outA=0X00;
    delay();
  }
  volatile unsigned char *outB;
  outB=0X25;
  for(int j=0;j<8;j+=2){
    *outB=(1<<j)|(1<<(j+1));
    delay();
    *outB=0X00;
    delay();
  }
  for(int j=6;j>=0;j-=2){
    *outB=(1<<j)|(1<<(j+1));
    delay();
    *outB=0X00;
    delay();
  }
  for(int i=6;i>=0;i-=2){
    *outA=(1<<i)|(1<<(i+1));
    delay();
    *outA=0X00;
    delay();
  }
}