13-04-2013, 04:25 PM
DESIGN AND IMPLEMENTATION OF COUNTERS
AIM
To design and implement a 4 bit Synchronous and Asynchronous counter using JK Flip
Flops.
THEORY:
Synchronous Counter:
A counter is a register capable of counting number of clock pulse arriving at its clock
input. Counter represents the number of clock pulses arrived. A specified sequence of states
appears as counter output. This is the main difference between a register and a counter. There are
two types of counter, synchronous and asynchronous. In synchronous common clock is given to
all flip flop and in asynchronous first flip flop is clocked by external pulse and then each
successive flip flop is clocked by Q or Q output of previous stage. A soon the clock of second
stage is triggered by output of first stage. Because of inherent propagation delay time all flip
flops are not activated at same time which results in asynchronous operation.
Asynchronous Counter:
Asynchronous decade counter is also called as ripple counter. In a ripple counter the flip
flop output transition serves as a source for triggering other flip flops. In other words the clock
pulse inputs of all the flip flops are triggered not by the incoming pulses but rather by the
transition that occurs in other flip flops. The term asynchronous refers to the events that do not
occur at the same time. With respect to the counter operation, asynchronous means that the flip
flop within the counter are not made to change states at exactly the same time, they do not
because the clock pulses are not connected directly to the clock input of each flip flop in the
counter.
PROCEDURE:
1. Connections are given as per the circuit diagram on the bread board.
2. The power supply is switched ON and set a voltage of 5 Volts.
3. If the input to be given to a gate is logic ‘1’ then it is connected to +5 Volts and if the input to be given to the gate is logic ‘0’ then the particular input terminal is connected to ground.
4. Truth table of 4 bit Synchronous Counter is verified.
5. If the output is logic ‘1’ then the LED glows, if the output is logic ‘0’ then the LED does not glow.