Hi Waqar,

I applaud you for your persistance.

You explanation of how you did your pulse detection was completely baffling, and I can't imagine that you got it working. But your algorithm description later in this thread was pretty straight forward. It should be simple to implement.

OK. You say you've done your research and read all the replies, but just need a little example. Your persistance, but not your effort, is paying off.

Here is a simple state machine to keep track of various states and inputs while unlocking a combination lock. There's a lot left undefined here, but it should be obvious what I'm trying to do, even if I've mistyped.

void combination_lock (void)
{
static char state = LOCKED;

switch (state)
{
case LOCKED:
if (turn_direction == RIGHT)
state = GET_FIRST_NUMBER;
break;

case GET_FIRST_NUMBER:
if (number == FIRST_NUMBER)
state = TURN_AROUND_1;
else if (turn_direction == LEFT)
state = LOCKED;
break;

case TURN_AROUND_1:
if (turn_direction == LEFT)
state = GET_SECOND_NUMBER;
else
state = LOCKED;
break;

case GET_SECOND_NUMBER:
if (number == SECOND_NUMBER)
state = TURN_AROUND_2;
else if (turn_direction == RIGHT)
state = LOCKED;
break;

case TURN_AROUND_2:
if (turn_direction = RIGHT)
state = GET_THIRD_NUMBER;
else
state = LOCKED;
break;

case GET_THIRD_NUMBER:
if (number == THIRD_NUMBER)
state = UNLOCKED;
else if (turn_direction == LEFT)
state = LOCKED;
break;

case UNLOCKED:
if (turn_direction == RIGHT ||
turn_direction == LEFT)
{
state = LOCKED;
lock_status = CLOSED;
}
else
lock_status = OPEN;
break;

default:
state = LOCKED;
lock_status = CLOSED;
}
}

Don't ask me to translate C to assembler...I use a compiler to do that, you can do it as you choose. Likewise, it's your task to understand the concept enough to apply it to your project.

Dennis