DE Unit 9: Synchronous Counters

Flip Flops in Action Again


 Download the Unit Rubric

A “Bug Bot” is a small robot that moves by itself with no program.  A successful Bug Bot moves like this:

  • It drives forward on its own as two motors spin
  • When the Bug Bot hits something its antennae bumps a switch
  • The switch makes one of the motors turn in reverse to the Bug Bot can move around things

Bug Bots are special because they do not require a program.  Instead, the batteries, motors, and switches are hard-wired in such a way that the mechanisms function on their own. As you design and build your own Bug Bot, we’ll go through three major steps:

  1. Wire it using the common wiring diagram to wire, test, and solder your Bug Bot’s wiring
  2. Design and draw what you want your Bug Bot to look like when it’s done
  3. Build your Bug Bot so it looks cool and functions properly

When you’re done, you’ll have your own working Bug Bot!

PART 1: Synchronous Counters

(20 pts)  About 3 days

Last unit we studied asynchronous counters, where each digit incremented individually and the increment to the counter rippled down the digits.  Synchronous counters – introduced here – will have each digit counting at the same time (synchronously).  With this tool, we’ll be able to make faster counters with a more complex circuit.

PART 2: Medium Scale Integration

(20 pts)  About 4 days

There are some IC chips that are more complex than simple AND/OR/INVERTER and the like.  These Medium-Scale Integrated (MSI) chips provide new tools like built in counters that can be easily breadboarded or simulated for PLD upload.  Here you get to play with a few of those and see how they work.

PART 3: 60 Second Timer

(30 pts)  About 3 days

Now for the real challenge: designing and building your own counter!  Here you’ll combine all of the knowledge you’ve gathered on flip-flops and synchronous counters to create a complete 60-second timer circuit.  You’ll design it with two kinds of logic and two seven segment display drivers to get everything working.

 Download the part 1 rubric

 Download the part 2 rubric

 Download the part 3 rubric

PART 1: Synchronous Counters

Creating your first synchronous counters

Synchronous Counters Overview

We spent the last unit looking at asynchronous counters.  In them, we used flip-flops of different types to create counters that counted up or down, had reset and suspend functions, and combined all of these into the giant “Now Serving” display circuit.  The biggest problem with asynchronous counters is that the numerical value needs to ‘carry over’ from digit to digit as the flip-flops cycle.  This ripple-effect wasn’t a big deal for our 2-bit counters, but as counters get more and more complex it can become a large problem.  The solution?  synchronous counters.


 Take 2 pages of detailed notes on the Synchronous Counters presentations.

Complete the Synchronous Counters Assignment

 Make sure all your simulated circuits work correctly in Multisim

 Have Mr. Benshoof confirm your working simulations


Synchronous Counters Introduction

Asynchronous vs. Synchronous

Detailed Synchronous Counter Explanation

What’s Due In Synchronous Counters Part 1: Synchronous Counters

  • Synchronous Counter Notes
  • Synchronous Counter Assignment
  • Successful Simulations
  • Benshoof’s Check-Off

Here’s what’s due in Part 1: Synchronous Counters

  1.  2 pages of detailed notes from the Synchronous Counters presentations
  2. Complete the Synchronous Counters Assignment
  3. Confirm that your simulated synchronous counters work as intended
  4.  Have Benshoof check-off your working simulations

PART 2: Medium Scale Integration

Using MSI IC chips in the development of counters

MSI Introduction

Synchronous counters are so useful - and used so often - that they've been combined into a Medium Scale Integrated (MSI) IC Chip.  These IC chips are self-contained binary counters that use internal flip-flops to make the job of counter creation much simpler.  In this part of the unit we'll focus on two specific MSI IC Chips: the 74LS163 Up-counter and the 74LS193 Up/Down-counter.  These tools will make some pretty fancy circuits a little simpler to put together!


 Take 2 pages of detailed notes on the various MSI presentations.

Complete the MSI 74LS163 Counters Assignment

 Breadboard your final 74LS163 circuit

Complete the MSI 74LS193 Counters Assignment

 Breadboard your final 74LS193 circuit

 Have Mr. Benshoof confirm your working simulations


Medium Scale Integration

74LS163 Upcounter Description

Example 74LS193 Circuit

What's Due In Synchronous Counters Part 2: Medium Scale Integration

  • MSI Notes
  • 74LS163 Upcounter Assignment
  • 74LS163 Breadboarding
  • 74LS193 Up/Down Assignment
  • 74LS193 Breadboarding
  • Benshoof's Check-Off

Here's what's due in Part 2: Medium Scale Integration

  1.  Take 2 good pages of notes on Medium Scale Integration
  2. Complete the MSI 74LS163 Counters Assignment
  3. Complete the breadboarding of your 74LS163 Up Counter
  4. Complete the MSI 74LS193 Counters Assignment
  5. Complete the breadboarding of your 74LS193 Up/Down Counter
  6.  Have Benshoof check-off your working circuits

PART 3: 60 Second Timer

Combine all the ideas of synchronous counters into one large circuit!

60 Second Timer Overview

In this last part of the unit, your job is to combine all the ideas from the rest of this unit - and from unit 8 - to make one large circuit that can function as a 60-second timer.  As you do this, you'll create a complex circuits with three main parts.  First, your circuit will need the one's place counter which will be built with an MSI logic (from part 2).  Next, that counter will carry-over to the ten's place counter which will be built using the SSI logic (from part 1) of J/K flip-flops.  Finally, those two systems will put out their signals to a pair of 7-segment display drivers paired with displays.  Together, you'll create a circuit that counts from 00 to 60 and then stops and can be reset.


 Document your design process in your engineering notebook

Complete the 60-Second Timer Challenge

 Breadboard your 60-Second Timer using your CMODS6 chip

 Have Mr. Benshoof confirm your working simulations


What's Due In Synchronous Counters Part 3: 60-Second Timer

  • Document Design Process
  • 60-Second Timer Assignment
  • Breadboard Timer
  • Benshoof's Check-Off

Here's what's due in Part 3: 60-Second Timer

  1. Document your entire design process
  2.  Complete the 60-Second Timer Challenge
  3.  Complete the breadboarding of your 60-Second Timer using your CMODS6 Chip
  4.  Have Benshoof check-off your finished timer

Double Check: Unit Expectations

Check what you need to have completed by the unit deadline

The purpose of this unit is to learn how a variety of new tools can be used to create synchronous counters.  You should have worked with J/K Flip Flops to create counters, then with the MSI 163/193 IC chips.  Finally, you should have combined all those ideas into one complete circuit that functions as a 60-second timer.  By the unit deadline, you should have completed and be able to submit the following items:

Engineering Notebook:

 (Part 1) Synchronous Counter notes

 (Part 2) Medium Scale Integration (MSI) Notes

 (Part 3) Documentation of your 60-Second Timer design process

Building & Making:

 (Part 1) Synchronous Counter Assignment

 (Part 1) Multisim your J/K Flip Flop synchronous counter circuit

 (Part 2) MSI 74LS163 Assignment & Breadboard your final 74LS163 circuit

 (Part 2) MSI 74LS193 Assignment & Breadboard your final 74LS193 circuit

 (Part 3) 60-Second Timer Assignment

 (Part 3) Breadboard your 60-Second Timer using the CMODS6

Benshoof Checkpoints

 (Part 1) Benshoof should have seen your working counter simulations before you moved on

 (Part 2) Benshoof should have seen your working breaboards before you moved on

 (Part 3) Benshoof should have seen your working 60-second timer