The attached narrated power point presentation reviews the construction, working and timing diagrams of ring and johnson counters as well as asynchronous and synchronous up, down, up/down and decade counters using popular flipflop ICs. The material will be useful for KTU B Tech second year students who prepare for the subject CSL 202, Digital Laboratory.
2. 2
Contents
• Counters using Flipflop ICs.
• Ring and Johnson Counters.
• Asynchronous Counters.
• Synchronous Counters.
• UP/Down Counters.
• Decade Counters.
• Timing Diagrams.
• Counter Applications.
3. 3
Counters using Flipflops
• Use of D flipflops or JK flipflops in T flipflop
configuration.
• Each flipflop divides input frequency by
two – frequency divider.
• Counters can be binary or biquinary.
• Binary Counters – straight sequence.
• Biquinary Counters – skip interim states.
• Counters can be synchronous (clock
driven) or asynchronous (ripple counter).
5. 5
Asynchronous Counters
• Also called ripple counters.
• Clock trigger to toggle LSB.
• Output of one flipflop to serve as clock for
succeeding flipflop.
• Number of flipflops depend on maximum
count and the total number of states of the
counter.
• Maximum number of states = 2N, N –
number of flipflops.
6. 6
Synchronous Counter
• All flipflops clocked from a single source.
• Clock common to all flipflops.
• Flipflops change states in synchronism
with the clock.
• Number of flipflops depend on the
maximum count and total number of states
of the counter.
• Maximum number of states = 2N, N –
number of flipflops.
27. 27
Procedure
• Assemble the circuits on the breadboard
provided along with the trainer kit.
• Initial reset/clear and LSB preset for the
ring counter.
• Clock input to be applied from the clock
source provided in the trainer kit.
• Outputs to be observed using LEDs
provided in the trainer kit.
• Verify the state tables and draw timing
diagrams.
