A little quick one:

In the previous article we mentioned sequential circuits, the type of circuits that can "remember" states, depending their outputs on these previously saved states and the signal introduced. We also talked about one specific example of these circuits, the Shift Registers, elements that shift states from bit to bit in a particular sequence. In this case, we'll talk about other sequential device in particular, the counter.

Let's begin.

What is a counter?

A counter, as you can suppose by Its name, Is a sequential device, formed by either J-K or D type latches (depending on the situation) that can count up or down to a determined amount of states in a working cycle (By example, counting from 0 to 16 in BCD code). In this case we'll focus on Binary Counters, the ones that have their sequences according to the binary code.

Types of Binary Counters:

While referring to these devices, what usually separates them is the way that their clock signals are introduced, having for this two categories:

• Synchronous Counters

• Asynchronous Counters.

Synchronous counters are defined by the fact that the clock signal in all the Latches that form their Logic Diagram are introduced from a common source. Meaning this that all the data is introduced at more or less the same time with every single pulse.

Asynchronous counters are a little bit more tricky. All the clock inputs are not connected to the same signal, due to the fact that they are connected to the previous flip flop output, depending on the state of the latter to trigger any operations in these. In this case, the data has certain delay from flip flop to flip flop while responding to the previous device signal.

A Counter's Module:

The module of a counter is simply the amount of states that a counter can pass through in every work cycle before resetting to Its initial state (Think of It as the amount of states that the counter can count). For example, If a binary counter can count up to 16 states in binary (0000 to 1111), that means It is a MOD-16 counter.

We hope, that as in all our articles, the information provided here can be of use to you and the projects you realize in the future, recommending always to take appropiate measures in order to not damage the IC used.