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Introduction

Counter

Counters are beside the logic operations the basic elements of all digital controls.

Since the clock pulses occur at known intervals, the counter can be used as an instrument for measuring time and therefore period or frequency.

On principle there are two counting organisations:

- Asynchronous (serial, ripple) counter

Each Flip-Flop is triggered by the previous Flip-Flop, and thus the counter has a cumulative settling time. (Delay time, tp)

- Synchronous (parallel) counter

Here, every Flip-Flop is triggered by the clock (synchronous), and thus the settling time is simply equal to the delay time of a single Flip-Flop.