Posted by John Chappel on January 21, 1998 at 14:04:53:
In Reply to: More Questions posted by Jim on January 20, 1998 at 08:48:11:
The handout assumes a synchronous reset. You can use an asynchronous reset
with minor changes.
: 2) Can someone give a couple examples of bit stuffing, specifically what about this 'last packet idea'?
If the original data is 0111111111111 (12 1's in a row), change it to
011111101111110 before performing NRZI encoding.
The easiest way to do this is to take the original data from a shift register.
As you shift it out, count the number of consecutive 1's. If you get 6
consecutive 1's stop shifting and send a 0 to the NRZI encoder instead.
: 3) In general doesnt bit-stuffing corrupt your data?
Bit stuffing changes the data, so you have to "unstuff" it at the receiver.
After NRZI decoding, shift the data into a shift register. As you shift
it in, count the number of consectutive 1's. If you get 6 in a row,
stop shifting and discard the next bit (which better have been a 0).
: 4) What das heck does 32'h55aa1234 and 16'haaaa mean?
n'hx means an n-bit number in hexidecimal format with the value x.
Ex: 3'h5 = 101
: 5)I assume that the packet to send out has no spaces inside, because that would eliminate the point of synchronizing with the clock? In other the whole packet is created somehwo first, then sent out all in one shot?
Correct, there cannot be any spaces.
: 6) This is a BIG lab, are we expected to get the whole thing done!?
Yup.