Binary Counter in Digital Electronics

In digital electronics, a binary counter is a type of sequential logic circuit which is able to count in binary numbers. A binary counter can counter from 0 to 2(n-1), where n is the total number of bits in the counter.

Basically, a binary counter is a type of digital circuit which counts the number of clock pulses that occur over a time period.

The binary counters are built up of flip flops, where a flip flop is a most elementary memory element that can store 1-bit of information. In a binary counter, each flip flop represents one bit of the binary number. The counter increases its count by one whenever a clock pulse occurs.

For example, a 3-bit binary counter can count from 000 (0) to 111 (7) before wrapping around to 000 again. We can design a binary counter to count up or down. Also, a binary counter has more advanced features such as ability to reset the count to zero, to load a specific count, etc.

Now, let us discuss different types of binary counters.

Types of Binary Counters

There are many types of binary counters present. Some common types of binary counters are defined as follows −

• Asynchronous Counter − The type of binary counter in which the flip flops do not receive the same clock pulse at the same time is called an asynchronous counter. The asynchronous counter is also known as ripple counter. It is the simplest type of binary counter. In the case of asynchronous binary counter, each flip flop is triggered by the output of the previous flip flop. Therefore, the asynchronous counters suffer from propagation delay.

• Synchronous Counter − The type of binary counter in which all the flip flops receive the same clock pulse at the same time is known as a synchronous counter. Since, all the flip flops of the synchronous counter are triggered by the same clock pulse, therefore, their outputs change simultaneously. This will result in the no propagation delay between the flip flops.

• Up Counter − The type of binary counter that counts upwards from zero to its maximum count value is known as up counter. In the case of up counter, the count is increased by one on each clock pulse.

• Down Counter − The type of binary counter that counts downwards from its maximum count value to zero is known as a down counter. In the down counter, the count value of the counter is decreased by one on each clock pulse.

• Up/Down Counter − The type of binary counter that can count in both upward and downward directions is known as a up/down counter. In the up/down counter, the direction of count is determined by a control input signal.

Design of Binary Counter

The general procedure that is followed for designing a binary counter is described in the following steps −

Step (1) − Determine the count range

Firstly, we have to determine the count range of the counter. It involves determining the minimum and maximum values that our binary counter has to count. This count range depends upon the application requirements.

Step (2) − Select the number of bits

In this step, we have to select the number of bits required for the counter. The number of bits depends upon the requirement of the count range. The count range of a binary counter is given by 2n, where n is the number of bits. For example, a 3-bit counter can count up to 8 different values, ranging from 000 (0) to 111 (7).

Step (3) − Select a proper counter type

Depending on the application requirements, select a proper type of counter. The chosen counter should have speed and accuracy required by the application. For example, asynchronous counters are used in simple and less expensive applications, whereas synchronous counters are used in applications where timing is critical.

Step (4) − Select the flip-flops

In this step, we have to choose the flip-flops used to implement the counter. The selected flip flops must be able to handle the desired count range and the clock frequency. In binary counters, the D flip flop is most commonly used type of the flip flop.

Step (5) − Write the excitation table and derive the minimal expression

Write the excitation table of the flip-flop for the counter as per the given state diagram. And derive the minimal expressions using K-map.

Step (6) − Design the counter circuit and test it

Connect the flip flops as per the expressions and test the counter to ensure that it counts correctly and reliably.

Advantages of Binary Counter

The major advantages of binary counters are listed as follows −

• Binary counters have high accuracy, i.e. they count number of clock pulses that occur over a time accurately.

• Binary counters consume less power because they are generally designed by using low power logic gates and flip flops.

• Binary counters are easy to design as they can be realized by using standard logic gates and flip flops.

• Binary counters have fast response. Therefore, they can operate at high clock frequencies.

• Binary counters are reliable. Thus, they can work for a long period of time without requiring maintenance.

• Binary counter is a versatile device as it can be used in a wide range of applications such as frequency dividers, digital clocks, etc.

Limitations of Binary Counters

The following are the major limitations of binary counters −

• Binary counter can count in a limited range, where the maximum limit of the counter is determined by the number of bits.

• Binary counter produces an output signal in the binary form which is limited to some applications and for more applications, it requires an additional circuitry to convert it in a suitable form.

• Binary counters are susceptible to electronic noise which may cause errors in the counting.

Applications of Binary Counters

Binary counters are used in numerous digital systems. Some common applications of binary counters are listed below.

• Binary counters are used in digital clocks and other digital timing devices.

• Binary counter can be used as a frequency divider, where it divides the frequency of the input signal by a fixed value.

• Binary counter can also be used as a shift register.

• In digital systems like computers, binary counters can be used as memory address decoders.

• Binary counter can also be used as a sequence generator, where it can generate sequences of binary codes.

• Binary counters can be used in error detection and correction applications.

This is all about binary counters in digital electronics. In conclusion, the binary counter is a versatile device used in several counting applications in digital electronics.