Random Thoughts On Studying

Quick even more random note...Still trying to figure out how I want this blog to be laid out, as for now its just my current thoughts at the moment. Hopefully it will also contain some useful engineering knowledge for those who are looking to jump on the Electrical Bus...no pun intended.

I have been pretty busy with work and summer classes as I have reached the point where I must start studying in order to catch up with the material. Its funny how it works out where you don't start actually trying until you realize you have a midterm the next week.

This led me to go through my study music I decided on a couple crucial points for effective studying.

• Classical music works very well as it eventually just turns to relaxing background noise
• Dubstep just leads to facebook surfing / fist pumping
• Rock unfortunately leads to pencil drumming
• Sounds of nature leads to a relaxing and much needed nap

Although music can never be a solution to the ultimate problem... Procrastination! So watch this video to get some motivation and study.

Flip Flop Basics

Flips Flops...when I first encountered them in ENEE244 I had no idea what they were besides a funny name. I came into the course knowing absolutely nothing about digital components or really how a computer functioned on the hardware level.

What I am going to briefly cover here (in probably a multiple part series due to the important nature of the material) is the essence of chapter 6 in Givones book.

Basic logic elements and, or, not xor, etc gates have well defined uses and are easy to see how to implement. If your basic circuit or task requires you to two input sources to be logical 1, or high (1 in the binary world, or typically +5 volts) in order for the output to be a logical 1 you would use an and gate.

Flip-Flops are a sequential network, or one that has "memory" and are its heart is a bistable element.

This is the first hurdle one must conquer, understanding how this works. Imagine X is a 0, then the output of the top not gate will be logical 1. this is also connected to the input of the lower not gate and therefore its output or Q' is logical 0. It is a complementary device and one might wonder well it seems common sense, but what are its applications?

Good Question! This is were Flip-flops come in to play, they are bistable elements that also have inputs and will hold their output states as long as it is connected to some power source (usually denoted Vcc). We will consider synchronous flip flops that run off of a clock in order to function.

We will skip over latches as they are essentially identical to flip-flops except for the fact that they respond continuously to inputs...they are level triggered.

You can have many different types, SR, D, T, and JK. They all have their own specific truth table but have the same underlying function of storing a piece of information.

What you can do with these is the interesting part. Any system you want to build or design can be constructed using flip-flops if it needs some form of memory.  A Shift Register is a great example of a simple flip-flop implementation and will be covered in the next article! More complex examples include computer memory.

Flip-flops take some time to really understand and my goal is to have some "sample projects" as the focus of the next couple articles to walk through the actual design process.

Water Cooling and Computer Part Sale

Water cooling a system has always been something I have wanted to do, not necessarily because I hated hearing fans constantly running while I was studying or doing homework (read playing Starcraft II). It was mainly something that just sounded fun.

This website has a great overview of water cooling and should be read over if your considering doing it yourself.

The cost is the major deterrent for most when considering the water cooling route, as it was for me, however with Fathers Day approaching everyone is having 'Dad-centric' sales...Computer parts are always included in that.

Amazon has a great offer right now, practically anything from memory, hard drives, to water cooling are listed as on sale. This will bring you to their list of items on sale. If you are looking for the water cooling, just do a quick search on it, and one of the best items on sale and about to run out is the actual water used in the system

Circuit Building labs

Hopefully the first two posts serve as a helpful introduction into peaking one's interest into EE and digital design. However, only so much can be accomplished in so little space. The primary way to jump into Electronics is to get your hands dirty with circuit building.




The book displayed on the right Practical Electronics for Inventors is a great book for circuit tips and guides for any electronic hobbyist -- which means its written in a clear easy to understand nature. Highly recommend to further your knowledge, and its cheap.

The University of Maryland offers many labs for this exact purpose. There are four required labs that range in difficulty and topics covered.

• Digital design lab (building circuits like the one mentioned before, but includes verilog programming) ENEE245
• Basic analog circuits, such as rectifier circuits and analog to digital converters. ENEE205
• 300 level transistor based lab, circuits include audio amplifiers and am transmitters/receivers. ENEE307
• 400 level lab of your choice, microprocessor lab, communications lab, etc..

These labs will help cement your basic understanding of the theory and strengthen your ability to work in the industry after graduation. Plus its just pure fun to construct circuits.

An example is an audio amplifier circuit I constructed with my lab partner and hooked up to our cellphones. It took the audio input from our cell phone's, properly amplified it over the frequency range and was used to drive a speaker

 Note: the music used was Dubstep...makes the circuit that much better

Digital Design Example

This will be a continuation from yesterdays post on the foundation of Digital logic and Design. As stated before this is not going to be an in depth explanation of all things digital logic. Givone's Book does a great job of explaining (something ENEE244 does not do) all things digital. However I will in this part go about the process of designing a simple 7 Segment LED display in order to show the power and simplicity of digital design. This design has pre-assembled IC Chips you can purchase to accomplish this, but it is more fun to do it yourself!

7 Segment LED Display

This project will utilize some of the fundamental design principles but will not cover everything. there are many topics covered in the course ranging from K-maps and how to simplify logic, but this will give a upfront idea of what you can do with this knowledge (in a very simple project).

The basic outline of this circuit is:

Where the 4 lines on the left are the inputs (a,b,c,d) and they are sent through a network decoder, accepting the inputs in 8421 format. So 1111 = 8+4+2+1, where 1000= 8+0+0+0, etc.

The decoder breaks this down into 7 outputs (a through g) which each corelate to one segment of the display.

You can have it set up anyway obviously, but if it were set up as above, where if a is high, that segment is on then the truth table for the outputs would look like.

W,X,Y,Z correspond to the for inputs (and correlate to the decimal number desired to be displayed). There are other possible conditions for inputs such as 1010, 1011,1100,1101,1110,1111 but these are 'Dont Care' conditions due to the fact we only want to display decimal numbers. These DC's are used in the K-map simplification of the circuit and is thoroughly discussed in the textbook.

I wont cover the k-map process here but the end result is a digital logic equation for each segment (a through g).

• a = w + y + xz + x'z'
• b = x' + y'z' + yz
• c = x + y' + z
• d = w + yz' + x'y + x'z' + xy'z
• e = x'z' + yz'
• f = w + y'z' + xy' + xz'
• g = w + xy' + x'y + yz'

What you would do with these equations is then create a "chip" from logic gates either by creating the gates from transistors (would be a pretty busy breadboard) or using pre-constructed logic gate chips.

However, these days there are IC chips that accomplish this as well as including some nice troubleshooting/data saving features. The 4511 chip comes to mind.

It may seem like a lot of work for a simple display, but once you go through the process it becomes second nature and then anything you wish to implement becomes possible

If there are any questions/suggestions please leave a comment.

-Brian

Foundations of Digital Design

The outlined road map for most students in EE at UMD (they change it every now and then: can be found here) has digital logic, ENEE244, covered before basic circuit theory. I agree with this layout as digital circuits are extremely easy to understand fundamentally and then provide the motivation to conquer analog circuits.

The textbook for this course, which is 100% needed, is Digital Principles and Design with CD-ROM It can be found pretty cheap used on amazon, whereas the bookstore on campus sells it new for $193.00 (rip off).

Regardless of who teaches this course, Silio or Nakajima, this book will be your number one source of learning.



Note: Both professors have terrible reviews (see ourumd.com for reviews), but both follow very similar exam format and questions. The class really isn't that bad as long as you put forth some effort.

If you wish to pursue computer engineering or anything digital related, this class is an extremely important foundation. It is also in my opinion the last "weed" out course for the degree program.