Counters
- Sequential circuit that goes through a prescribed sequence of states upon the application of input pulses is called a counter.
- In a counter, the sequence of states may follow a binary count or any other sequence of states.
- Counters are used for counting the number of occurrences of an event and are useful for generating timing sequences to control operations in a digital system.
- A counter that follows the binary sequence is called a binary counter.
- An n-bit binary counter consists of n flip-flop and can count in binary from 0 tot”-1
- Up counters increasers in value and down counters decreases in value.
Asynchronous Counter (Ripple Counter)
In ripper counter tree flip-flop output transition serve as a source for triggering e.g., in a binary ripple counter consists of a series connection of complementing flip-flops (T or JK), with the output of each flip flop to the CP input of next higher order flip-flop.
Synchronous Counter
Synchronous counter is distinguished from ripple counter such that in synchronous counter clock pulses are applied to the CP inputs of all p-flop simultaneously, rather than one at a time in succession as in ripple counter.
The decision whether flip-flop is to be complemented or not is determined from the value of J and K inputs at the time of the pulse.
Registers
- A register consists of a group of flip-flops with a common clock input. R’s4ster are commonly used to store and shift binary data.
Key Points
An n bits register has a group of 0 flip-flop which can store a binary information of n bits.
ShirtRegister
It is a register in which binary data can be stored and then shifted left or right when a clock pulse is applied , Bits shifted out one end of ther the register may be either lost or shifted back in on the other end.