Friday, October 28, 2016

Ring Counter

A ring counter is circuit made up of N flip flops as shown in the figure below. It is used to generate N unique states from the N flip flops in a simple way. We can generate N unique states from counters too, but that would need more complex circuit than a simple ring counter.

As shown in the figure above the output of the last flip flop becomes the input to the serial input of the first flip flop. As shown in the truth table below, when we start the sequence from 1000 as the output of the flip flops, each clock pulse causes the 1 bit to shift to the next flip flop. Thus in any state the output of only one flip flop is going to be high, thus uniquely identifying the sate as highlighted in the truth table.

An N state ring counter will need N flip flops.

The video below shows the operation of a ring counter .

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