What is an LFSR (Linear Feedback Shift Register)?
If you can find an LFSR diagram, you will see that it is just a shift register of n-bits. Depending on the desired count sequence, different bits are tapped at the outputs of the individual flip-flops (registers), and these bits are taken as inputs to an XOR gate and then fed back to the shift input of the entire shift-register. As far as I know, there is no direct, easy way to determine what bits to tap as feedback for a given count sequence. Computer programs exist to help figure that out, and there are also tables published that describe which taps to choose in order to get the maximum count sequence before repeating a bit pattern (2^n -1 counts) LFSRs are useful in certain circumstances. They can provide an efficient implementation of a counter (can you see why it is efficient?), however the count sequence is “pseudo-random”, in other words it is not intuitively predictable, but it is repeatable. This is useful in many testing applications, and also in applications where you need t
