Need a Quick Mod-N Counter?

Despite living in the world of programmable logic and readily accessible off the shelf digital solutions, there may be times in which constructing a small counter from scratch will be much more cost effective and time efficient. For times such as these, the shortcut method to creating counters is a valuable and simple technique to have in the back of your mind.

That being stated, there are two caveats, maybe more, to this technique that must be known. The first and foremost is that the generated logic may not always represent the most efficient use of logic gates; thus this technique, when applied to the letter, fails to take into account redundancies. The second caveat is that attempting to apply this technique to more exotic counting progressions will result in either failure or a very convoluted answer and therefore must be dealt with by other techniques. Both of these troubling aspects can be mitigated by either using other techniques as a supplement and/or employing the use of good 'ole inspection (I think I've heard the word 'inspection' in every EE class I've been in -.- ).

I would like to express my gratitude to Dr. Nathan Dodge for teaching me this shortcut method in his EE2310 digital systems class during my freshman year at the University of Texas at Dallas.

Organization

• Page 01: Introduction - You are here
• Page 02: A Few Basics
• Page 03: Step 1 - How many bits?
• Page 04: Step 2 - Create a Generic Base-2 Counter
• Page 05: Step 3 - Comparison Table
• Page 06: Step 4 - Insert in the Required Gates
• Page 07: Step 5 - Wire up to the Final Count
• Page 08: More Info - Exotic Counting
• Page 09: Review - Quick Guide
• Page 10: Practice - You know you need it!
• Page 11: Answers - The good stuff

Disclaimer

Although this tutorial has been checked over, mistakes are certainly possible because I was probably writing this during the late nights and/or when I didn't want to do my homework (Yes, I have homework in college). Therefore, before attempting to replicate or borrow ideas, it would be wise to verify the information presented herein by yourself and/or with a 3rd party who has sufficient knowledge of the material.