A Johnson counter is a modified ring counter, where the inverted output from the last flip flop is connected to the input to the first. The register cycles through a sequence of bit-patterns. The MOD of the Johnson counter is 2n if n flip-flops are used. The main advantage of the Johnson counter counter is that it only needs half the number of flip-flops compared to the standard ring counter for the same MOD.
It can be implemented using D-type flip-flops (or JK-type flip-flops).
Truth Table | |||
---|---|---|---|
State | Q0 | Q1 | Q2 |
0 | 0 | 0 | 0 |
1 | 1 | 0 | 0 |
2 | 1 | 1 | 0 |
3 | 1 | 1 | 1 |
4 | 0 | 1 | 1 |
5 | 0 | 0 | 1 |
With advertising revenues falling despite increasing numbers of visitors, we need your help to maintain and improve this site, which takes time, money and hard work. Thanks to the generosity of our visitors who gave earlier, you are able to use this site at no charge.
If you have benefited from this site and are able, please give $10 via Paypal. It will allow us continue into the future. It only takes a minute. Thanks!