This is the only picture that was provided to me. I can\'t get it any clearer. 2

Question

This is the only picture that was provided to me. I can't get it any clearer.

2. A Linear Feedback Shift Register (LFSR) is a type of counter that generates a "pseudo random" sequence. They are used all over the place when you need "sort-of" random numbers. An LFSR will generate a random- seeming sequence of numbers, but they're pseudo-random because they repeat after some point in the se- quence. This turns out to be quite helpful in some situations where you want to be able to test things with the same sequence of numbers, but that sequence should be sort of random. A full LFSR will repeat after 2" 1 iterations. That is, it will have only one fewer number in the "counting" sequence than a full binary counter. In particular, note that this LFSR does NOT include 0000 in its counting sequence (a common issue with LFSRSD. So, if you clear the counter to all 0's it will never start counting. Instead you should "preset" the counter to all 1's. Thus, my schematic is using DFFs with preset instead of clear. There's a lot of math out there to reason about LFSR sequences (that we're not going to cover!). In this case I'll give you a four-bit 2 1 LFSR schematic (next page). Your job is (a) Write in ISE Verilog code for this four-bit LFSR (b) Write a testbench for this LFSR and simulate it c) Hand in the results of the simulation that clearly show the sequence of 4-bit values that this LFSR goes through.

Explanation / Answer

LFSR is nothing but Linear Feedback Shift Register is a sequential shift register with combinational feedback logic around it that causes it to pseudo randomly cycle through a sequence of binary values.

=> Feedback around LFSR's shift register comes from a selection of points in the register chainand constitute either XORing or XNORing these points to provide point back into the register.

=>The LFSR basically loops through repetitive sequences of pseudo random values. The maximum length of sequence is (2^n) - 1.

Please upload the clear picture so that i can answer the rest question also

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