DE Unit 8: Flip Flops & Counters

New tools for building asynchronous counters


Last semester we were briefly introduced to the idea of a “Flip Flop”.  Here, we will get into the details of the D-FlipFlop and the J/K-FlipFlop and see what can be done with them.  These tools help us store a single piece of information and use that to create more complex systems like counters.  As you learn about Flip Flops, you’ll go through three major steps:

  1. Learn how D-Flip Flops and J/K-Flip Flops work and how to wire them into circuits
  2. Learn how Flip Flops are applied in both shift registers and event detection
  3. Simulate Asynchronous Counters in Multisim

When you’re done, Flip Flops will be a new tool for you to use when developing

PART 1: Flip Flops

(20 pts)  About 3 days

This unit begins with an introduction to the use of Flip Flops.  We saw flip flops last semester in some of our circuits, but here we get to actually learn what they do and how to use them.  We’ll also see how flip flops can be used for event detection in circuits and then we’ll build examples in Multisim.

PART 2: Shift Registers

(30 pts)  About 3 days

Next we’ll investigate another application of flip flops: shift registers.  Shift registers will help us keep track of longer strings of bits and data, and will help us work our way into the more complex problem of building an asynchronous counter.

PART 3: Asynchronous Counters

(20 pts)  About 3 days

Here we’ll put together more complex asynchronous counters.  First we’ll build a modulus counter that will allow us to set the starting and ending value of the counter.  Then we’ll build in the functionality to be able to suspend the counter and the ability to reset the counter.

 Download the part 1 rubric

 Download the part 2 rubric

 Download the part 3 rubric

PART 1: Flip Flops

Learning about D and J/K Flip Flops

Flip Flop Pin Diagrams

 Flip Flop Assignment

The first thing we get to work on in this unit is our understanding of the Flip Flop.  Flip Flops are a tool that we can use in a digital circuit that helps us store single bits of information (individual 0’s/1’s) for use later on in the circuit.  Flip Flops come in two flavors: “D Flip Flops” and “J/K Flip Flops” that both can be used to hold bits of information.  We’ve seen them used in previous circuits that we built to make counters and random number generators.  Here we will investigate Flip Flops further and start to look at how they can be used in more complex circuit design.


 Take notes on the function of both D-Flip Flops and J/K-Flip Flops

 Take notes on applying Flip Flops in the creation of the Transparent D Latch

 Complete the Flip Flop Assignment

Flip Flops

Flip Flop Application: D-Latch

Flip Flop Explained

What’s Due In Flip Flops & Counters Part 1: Flip Flops

  • Notes: Flip Flops
  • Notes: Applications
  • Flip Flop Assignment
  • Benshoof’s Check-Off

Here’s what’s due in Part 1: Flip Flops

  1.  Take notes on the two kinds of Flip Flops and how they function
  2.  Take notes on some of the applications of Flip Flops
  3.  Complete the Flip Flop Assignment
  4.  Have Benshoof check-off your assignment

PART 2: Shift Registers

Flip Flop Applications

Asynchronous Counters


Flip Flops are relatively simple tools that can have very cool and complex applications.  Earlier you should have looked at event detection and how the Flip Flop can be used to trigger other actions in a circuit.  Here we get to look at how Flip Flops can be used as “shift registers”.  A shift register is a circuit that simply passes single bits of information ‘left’ or ‘right’ along the circuit.  Flip Flops are perfect for this.  In this part of the unit we’ll learn a bit about shift registers and see them in action as we build our first simple asynchronous counter.


 Take notes on the Asynchronous Counter and its function

 Complete the Shift Registers Assignment

 Complete the Simple Counter Assignment

What’s Due In Flip Flops & Counters 2: Shift Registers

  • Asynchronous Notes
  • Shift Register Assignment
  • Simple Counter Assignment
  • Benshoof’s Check-Off

Here’s what’s due in Part 1: Wiring

  1.  Notes on Asynchronous Counters
  2. Shift Registers Assignment
  3.  Asynchronous Counters Assignment
  4.  Have Benshoof check-off your careful drawing

PART 3: Build It!

Put your plan into action and build your Bug Bot in our workshop

Soldering – how to!  Give some thoughts and notes that summarize the big ideas

Check out this video on how to solder

Check out this video on how to wire your bugbot

Check out this extra video on troubleshooting

What’s Due In Bug Bot Part 3: Build It!

  • Build It
  • (Extra Credit) Decorate it
  • Benshoof’s Check-Off

Here’s what’s due in Part 3: Build It!

  1.  Get into the makerspace and build your Bug Bot!  Make sure it functions properly!
  2.  If you have extra time, give your Bug Bot that special touch by painting, lasering, or making stickers to customize it!
  3.  Have Benshoof check-off your finished, working Bug Bot

Double Check: Unit Expectations

Check what you need to have completed by the unit deadline

The purpose of this unit is to use the Engineering Design Process to wire, design, and build a working Bug Bot.  You should have had the chance to do some soldering, design your own Bug Bot, and use the tools in our makerspace to build your Bug Bot.  If you were really on-task and working hard, you should have also had time to decorate your Bug Bot to make it look super cool.  By the unit deadline, you should have completed and be able to submit the following items:

Engineering Notebook:

 (Part 1) Definition of problem, criteria, constraints, and Bug Bot Overview notes

 (Part 1) Wiring diagram, soldering notes, and wiring reflection

 (Part 2) Bug Bot Design brainstorm, notes, and careful drawing

 (Part 3) Final drawing/picture, half-page written reflection on Bug Bots

Building & Making:

 (Part 1) Wiring should work, soldering should be clean and complete

 (Part 2) Bug Bot design should be carefully drawn out including labels and diagrams

 (Part 3) The Bug Bot should be assembled and should function properly

Benshoof Checkpoints

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

 (Part 2) Benshoof should have seen your careful drawing before you moved on

 (Part 3) Benshoof should have seen your working Bug Bot