SEQUENCE GENERATOR USING FLIP-FLOPS

Sequence generators are a type of logic circuits used to give a prescribed or pre-desired output.  Counters are a special kind of sequence generators they pass through a definite number of states in a pre-determined order. There are mainly two types of counters - synchronous and asynchronous counters. In Synchronous counters, the flip flops are triggered with the same clock simultaneously whereas in Asynchronous counters the flip flops are triggered with different clock or from the output of previous flip-flops. There are various types of counters within them such as UP counter, DOWN counter and UP/DOWN counter. For instance, a 4-bit up-counter will count from 15 to 0 while the order is reversed in the case of 4-bit down-counter. These circuits when suitably manipulated by making a logic circuit are often made to count till an intermediate level as well. This means that rather than counting till 15 we can terminate the method by resetting the counter just at say 7.