SCHOOL OF ELECTROTECHNOLOGY

FACULTY OF ENGINEERING.City Campus

TRAINING Centre for Telecommunication,

Computing and Electrotechnology.

Counters.

Cliff Srahan, 2 April, 2001

A counter is a circuit that responds to a number of input pulses by

storing a binary number that is equal to the number of input pulses, up to a maximum or modulus number for that circuit.

generating one output pulse for the modulus number of input pulses

A counter has two related applications:

as a counter.

as a pulse divider.

As a counter, can count pulses, and so events that generate pulses. The modulus number is the highest number that a circuit can record.

As a divider, it can divide a number of pulses by the modulus number, that is, for each m pulses in, one output pulse is generated.

Practical counters and dividers must have a modulus such as 10, 16, 100. Such circuits have been designed, but they are relatively expensive. Practical circuits are based on digital flip flops, so we start our study with modulus 2 counters.

We need to cover:

Mod 2 counters, using D and JK flip flops.

Mod 4, 8,16 etc counters.

Mod anything counters using feedback.

Synchronous (parallel) and asynchronous (ripple) counters.

Refs:

Floyd Chapter 9.

http://www.wfu.edu/users/matthews/courses/p230/CM6/digital.html counter.ppt

http://members.spree.com/sip/jackwebb/dig6.htm __________________________________ find a couple of __________________________________ refs of your own.