In order to know the frequency value of the unknown counter, the connection is done in the way that unknown frequency is connected to one input and sample pulse signals are connected to other input of AND gate. Binary counters are the type of counters which follow a binary sequence and an n-bit counter is designed of “n” number of flip-flops where the count starts from 0 to 2n-1. In most of the digital kind of electronic circuits and applications, the digital counters are employed through Toggle flip-flops or by using any other kind of flip-flop which can be connected in the way to provide the essential switching operation, or else with the usage of specific counting integrated circuits like the 74LS90. There exist numerous kinds of counters which can be Mod 4, Mod 8, Mod 5, and Mod 16 counters, and many more. The Mod counter can count from ‘0’ to ‘2n – 1’. When a counter resets automatically after counting of ‘n’ bits, it is termed as Mod-n counter where ‘n’ corresponds to an integer. The number where the BCD circuit can count is termed as “Modulus” also called “Mod”. In this way, many counters can have a series connection in order to count up to our required number. The circuit counts from decimal ‘0’ to ‘9’ and after this NAND gate resets the circuits and starts to count again from ‘0’ that is 0000. So, the circuits hold the capability of counting 16 states (means 16 bits) where only 10 out of 16 are utilized. In the circuit diagram of the decade counter, the operation is explained in four stages where every stage is included with a flip flop. The most common implementation of this counter is in 74LS90 which is an asynchronous decade counter. A four-bit decade counter will operate as a BCD counter by skipping any 6 outputs from the 24 outputs. The values that a BCD counter counts are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 in binary format, and many others. As the counter counts ten unique combinations of the applied input, it is termed a decade counter. It performs the operation of resetting automatically when there is a new clock input signal. In consideration of this, this article today explains on BCD counter, its operation, design, and implementations? What is BCD Counter or Decade Counter?Ī BCD (Binary Coded Decimal) counter also termed as decade counter is a series type of digital counter which is designed to count ten digits. With this operation, counters are usually employed in many applications and these are designed as isolated IC’s and even integrated into huge integrated circuits. Every pulse that acts as input to the clock either increases or decreases the numbers count on the counter. The generally used type is a sequential digital logic circuit having an input line termed as a clock and has multiple output lines and the values those are on the output lines signify a number in the binary system. The one advantage of synchronous counter over asynchronous counter is, it can operate on higher frequency than asynchronous counter as it does not have cumulative delay because of same clock is given to each flip flop.įigure-2: Synchronous Counter Circuit and Timing Diagramįrom circuit diagram we see that Q0 bit gives response to each falling edge of clock while Q1 is dependent on Q0, Q2 is dependent on Q1 and Q0, Q3 is dependent on Q2,Q1 and Q0.In the scope of digital logics, a counter is a tool that accumulates the information of how many times a specific process or event is occurring probably like a clock. Unlike the asynchronous counter, synchronous counter has one global clock which drives each flip flop so output changes in parallel. In this way ripples are generated through Q0,Q1,Q2,Q3 hence it is also called RIPPLE counter. It is evident from timing diagram that Q0 is changing as soon as the rising edge of clock pulse is encountered, Q1 is changing when rising edge of Q0 is encountered(because Q0 is like clock pulse for second flip flop) and so on. We can understand it by following diagram-įigure-1: Asynchronous Counter Circuit and Timing Diagram In asynchronous counter we don’t use universal clock, only first flip flop is driven by main clock and the clock input of rest of the following counters is driven by output of previous flip flops. Classification of CountersĬounters are broadly divided into two categories For example, in UP counter a counter increases count for every rising edge of clock. Counters are used in digital electronics for counting purpose, they can count specific event happening in the circuit. Design and verify the 4- Bit Synchronous/ Asynchronous Counter using JK flip flop IntroductionĪ counter is a device which stores (and sometimes displays) the number of times a particular event or process has occurred, often in relationship to a clock signal.
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