read_ACK(15);

delay(100);

display(15);

}

void loop(){

send_tag();

read_ACK(25);

delay(100);

if (!cmp_id ()) {

if (test_ACK ()) {

display (25);

delay (100);

}

}

copy_id ();

}

void copy_id (void) {//save old id

int ai, oi;

for (oi=0, ai=19; oi<5; oi++,ai++) {

old_id[oi] = receive_ACK[ai];

}

}

char cmp_id (void){//return true if find id is old

int ai, oi;

for (oi=0,ai=19; oi<5; oi++,ai++) {

if (old_id[oi] != receive_ACK[ai])

return 0;

}

return 1;

}