What is a counter and its classification

Last Update Time: 2018-12-15 15:15:54


The process of counting the number of input pulses is called counting, and the digital circuit that can complete the counting work is called the counter.

The internal of the counter consists of a trigger, a trigger can be recorded as two states, so the counter composed of n flip-flops can accumulate the maximum number of counts for 2 ". A counter can accumulate the number of counts, called the module of the counter ( M ), also known as the count length of the counter. Commonly used counters generally refer to sequential circuits that count consecutive pulses. The so-called continuous count means that its state is incremented by binary number ( + 1 ) or decrement ( -1 ). The subscript 0 is always used to represent the lowest bit ( LSB ) in the state bit of the counter.

 In the counting process of the counter, in addition to the count of the input pulse, no other input signal is needed, and the count of the input pulse is generally used as an internal touch the clock signal of the transmitter is not considered to be a transmission signal, so the counter is considered to have no ( unnecessary ) input signal during the counting process. Many integrated counters have asynchronous clear end and other extended input terminals, and the output is always affected by the losers.

1. The classification of the counter

( 1 ) According to the circuit structure, the counter can be divided into an asynchronous counter and a synchronous counter.

The clock signal ( CP ) of each trigger in the asynchronous counter is not the same signal, and the actions of each output are not made at the same time, will be divided into successively, there are different delays. The clock input ( CLK ) of each flip-flop inside the synchronous counter is directly connected together, and the clock signal ( CP ) is the same signal, the action of each output terminal is controlled uniformly under the clock signal.

( 2 ) The counter can be divided into an addition counter, a subtraction counter and a reversible counter according to the counting method. The state of the adder counter increases with the input pulse in the binary number. The state of the subtracting counter decreases as the number of the input pulse is in the binary number. Reversible counter generally has a plus and minus counting control terminal, under its control, both can be added to count, can also be reduced count.

 ( 3 ) According to the count length ( the module of the counter ), it is generally divided into binary counter, decimal counter and any binary counter. A binary counter is a counter that counts the output according to the binary counting rule, and the count length is 2n, which is generally called the n-bit binary counter. The decimal counter is the counter ( 1001 ) 2 from ( 0000 ) 2 according to the binary count rule.

 

This article is from Allicdata Electronics Limited.

 

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