ArdIAC – Arduino Illustrative Aid to Computation

Way back in high school, I received a copy of the CardIAC computer simulator ( … omputation, there is also a great description with programs and an emulator: from my math teacher. The CardIAC is Bell Lab’s Cardboard Illustrative Aid to Computation, a great introduction to how computers operate on a very low level.  Earlier I had been introduced to the school district’s (School District 214, in North-Western Chicagoland) HP-2000 computer and taken to it like a duck to water. In learning HP’s TSB (Time Share BASIC) I wrote my first emulator, a CardIAC emulator. Unfortunately, I have no memory of the user interface, only the background. Over the past several years, I have wanted to recreate my emulator, but in hardware.

A while back, I ran across the Kim-Uno (a 6502-based KIM computer simulator: http://obsolescenceguaranteed.blogspot. … o-uno.html) which stirred my creativity. I recently ordered an Arduino Nano ( … 59231.html) and several Nokia 5110 LCD modules ( … 45893.html.) Time to play.

Here is my prototype as of this point (note that I have not done the initial wiring yet.)

I prefer to do my prototyping off of a CAD drawing, and then when everything works, it already matches up and so I can just have some boards manufactured.  So, this is what the ArdIAC drawing looks like to this point.

The ArdIAC, so far. The bottom portion is an existing hex keypad, that I designed for my store.

The next step is to get the prototype LCD wired up, and then load some testing code to display something on the LCD.

Since the CardIAC only has 100 words of memory, and the Arduino’s Mega328 has 2K bytes of RAM, this will be enough to simulate the CardIAC.  However, I am thinking of adding an external serial RAM, so that this thing can simulate/emulate more complex systems.

Ideas? Question? Suggestions?

Expanding Your 2313 Experimenter System

In the book Introduction to Microcontrollers, I alluded to the ability to expand your 2313 Experimenter System (2313ES.)  On page 70, I showed a drawing of a breadboard attached to a 2313ES.  This week, we will go ahead and expand our 2313ES with a medium-sized breadboard – this will provide pretty decent expansion capability, but will allow the 2313ES to keep it’s portability.

To start off, you will want to pick a piece of plastic, or something, to use as a base.  In this example, we use a plastic base plate

from Tamiya ( – Eddy was thinking about offering the base plates separately, write to him and ask him about this,) but you could use just about any flat-surfaced item.  Consider a small piece of thin plywood, a small piece of metal, or plastic, cut from the side of something from the trash, a small clipboard without the metal clip, or maybe even the inside of the lid of a plastic pencil case (back-to-school specials abound right now.) The important thing here, is to just make sure that your kit and breadboard (and battery box, if you want it,) will fit.

This 2313 Experimenter System expanded system.

This 2313 Experimenter System board is mounted to a Universal Plate kit from Tamiya to make our expanded system.

Once you find your base, peel the backing off of the sticky foam tape on the bottom of your breadboard, and stick the breadboard into place on your base.   Next you can solder two small pieces of jumper wire to the two power rail holes on your 2313ES printed circuit board (PCB.) Now, peel the backing off of the 2″X2″ foam tape that was included in your kit, and use it to mount your 2313ES near your breadboard.  Then plug the the power wires into the power rails of your breadboard (you could also use the left-most holes in the power rail female headers, of your 2313ES, for a less permanent solution.) Finally, mount your battery box (if you want it) to your base; make sure that you leave access to both the sliding door and the power switch, as they are on opposite sides of the battery box.  Also, if your breadboard has dual power rails on the top and bottom, you will need to connect the two +V, and the two Ground, rails, as we have on the right side of the photos.

Once you get your 2313ES and breadboard mounted, you will want to test the connections to make sure that everything is wired up properly. You can use a simple “blinkenlight” ( – this is the same as the small test device that you built while testing your 2313ES,) to test power; place the negative lead (the one with the resistor) into the ground power rail, and the positive lead into the +V power rail.  Place the power selection jumper over the Pgmr jumpers and connect the programmer and the LED should light up.  You can also simulate the blinkenlight by just plugging an LED and resistor in to the breadboard.

If the LED does not light up, there is a bad connection between the 2313ES and your breadboard.  Remember to disconnect power before changing any of  the wiring, here. Recheck the wires connecting the two pieces.  If you soldered the wires to the holes in the 2313ES, then disconnect one from the breadboard and temporarily replace it with a jumper plugged into the 2313ES’ female header for the power rail.  Connect power again and check that the LED lights up.  If it does, then the wire that you replaced is bad; recheck the soldering and maybe replace the wire.  If the LED still does not work, then remove power, temporarily replace the other wire and check again.  Again, do not forget to jumper the top and bottom V+ and Ground rails together.  LESSON LEARNED – When I first connected this breadboard, I accidentally connect both V+ and Ground to the same rails – not good!  Fortunately, this system is pretty durable.  The USBASP (or the USB port on the computer) detected the short, and just shut down the power to prevent damage.  As soon as I corrected that goof, everything worked again.

Once you get the LED to light, you may want to permanently mount the LED and resistor.  Take a look at the photo for how you may want to do this.  Once you get the parts placed and working, you will want to cut the leads short (make sure that you remember which LED lead is for the cathode (negative.)  This will keep the LED and resistor neat and out of the way – in fact, you may want to use a tiny bit of glue, or epoxy (or hot glue) to keep them in place, it will be more durable that way.

This will provide a quick, and easy, pilot light, to let you know when your 2313ES has power applied.  Just remember that the LED does draw power, even if you are not running any useful program on your Tiny2313 chip.  This is not a lot of current, about 20mA, but it will help to drain your battery, if you are using the battery pack.  Just make sure that you turn off the power switch on your battery box when you are not using the experimenter kit.

Next week, we will start adding stuff to the breadboard expansion.  Stay tuned.

Developing New Products

Today, we are going to start looking at developing new products.  We will begin with getting to know our development kit (starting off with the 2313 Experimenter System.)  This new product was developed, specifically to allow engineering students to learn about microcontrollers, and how to use them.  As an advanced part of learning how to use microcontrollers, you can use the 2313 Experimenter System to develop new products.

The 2313 Experimenter System (from now on, let’s call it the 2313ES for simplicity) provides you with an AVR ATtiny2313A microcontroller, from Atmel, a programming port, three LED lights, two push-button switches, a speaker, and two servo-motor/sensor I/O ports.  In addition, the 2313ES provides the ability to draw it’s power either from the programming port, or a battery – complete with protection from reversed polarity.  There are also two power strips available, to easily provide ground and +V connections for your circuits.  Right next to these power rails, there are additional drill holes to allow you to easily extend power to an optional breadboard.  Our first “product” will not be using the breadboard (don’t worry, we will expand the 2313ES later on.)

The Product
A couple of my kids have had to have braces.  Every kid who has had braces, has heard the admonition from the doctor to “make sure that you brush for three full minutes.”  Of course, when you are doing something that you don’t enjoy, time seems to crawl.  It is very difficult for a kid (of any age) to brush for a full three minutes – it seems to take forever.  So, our first product will be a simple tooth-brushing timer.  The requirements for this product will be pretty simple: start timing and let the user know when the three minutes have passed (by the way, you could also use this for a “time out” timer for young children for when they misbehave.)

The doctor’s office gave both of my kids a simple “hour glass”-style sand timer for them to use, and it does the job; however, I think that it can be improved.  That is what we will work for in this development project.

Developing The Timer
Let’s start off with the hardware side of the timer. Take your 2313ES and make sure that the programming cable is not attached and that the battery box is not turned on.  Now, run a short jumper wire from the the second from the right-most hole (or pin) on the Tiny2313 socket, labeled PB0, to the right-most LED (like the blue wire in the drawing to the right.)  Take a second wire and connect PB1 to the speaker terminal (as shown in yellow.)  This will give us all that we need to start developing the program (the firmware) for our new tooth-brushing timer.  That is one of the beautiful things about development kits (or dev kits;) it is really simple to set up your system for developing new products.  In fact, that is where the dev kit gets it;s name.

The Program
The program that will run our timer, is called the firmware – this is software that is always there, and cannot be easily changed (like you would change from a word processor to an internet browser on your desktop, or laptop, computer.) Normally, you would not want to change the program on your program on a control system.

We will develop our firmware in MCS Electronic’s BASCOM-AVR, as we used in the book, Introduction to Microcontrollers.  Launch your BASCOM program and enter the following:

‘ Title: Tooth-brushing Timer
‘ Author: Art Granzeier, Granzeier Consulting  – Use your name here.
‘ Date: 13 Oct 13  – Use today’s date here.
‘ Description: Delay for 3 minutes and then alert the user.

‘ Configuration Section
$regfile = “ATtiny2313a.dat”     ‘ Specify the micro
$crystal = 1000000                    ‘ Frequency for internal RC clock
$hwstack = 32                             ‘ Default – Use 32 for the HW stack
$swstack = 10                              ‘ Default – Use 10 for the SW stack
$framesize = 40                          ‘ Default – Use 40 for the frame space

Config PortB = Output

‘ Main Program
‘ Pause for 3 minutes

‘ Alert the user
‘ LED on

‘ Tone from speaker


(Note: don’t try to copy and paste from this page – the HTML code will make BASCOM cry.  Instead, use the .BAS file that I have posted here:  Read through the rest of this post first, because this .BAS file contains all of the additional statements as described below.)

This will provide the frame, or skeleton, for our new program.

Now, we need to start the program by counting up for three minutes, when the timer is turned on.  As we covered in the book, you could use the waitms command to wait for a specified number of milliseconds (thousandths of a second.)  Looking through the BASCOM manual (you did download that when you installed BASCOM, right?) we find that there is another command, related to the waitms – the wait.  Looking at this command, we see that this will wait for a specified number of whole seconds.  For longer delays, this is what we need.  Under the comment about pausing for three seconds, type the line:

Wait 180

This will cause the program to pause for 180 seconds, or three minutes.

Next, we need to notify the user that they have been brushing long enough. Under the LED on comment, under Alert the user, type this line:

Set PortB.0

This will cause the LED to turn on, just like the first experiment in the Intro book.  And, now, since we want the user to be notified, even if the kid is not watching the timer, we would add the following line under the tone comment:

Play PortB.1, 500, 125

That is all that we need to meet the initial product requirements for our new timer.  Make sure that the power selection jumper is set to power your 2313ES from the programmer.  Next, take your programmer and connect it up to your 2313ES and plug it into your computer.  Compile the timer program and download it into your ATtiny2313.  Now, unplug the programming cable from the 2313ES, and (with the battery box turned off) switch the power selection jumper back to the battery position.

Now, turn your battery box switch on, and wait.  Remember, that three minutes is a long time, when you are just watching and waiting (remember, “a watched pot never boils.”)  About three minutes after you turn the timer (err, your 2313 Experimenter System) on, the LED will light, and a short tone will come from the speaker.

Well, congratulations on developing your first product!  Of course, this is really the very beginning of your development process.  What you have here is more like your first, rough draft of a term paper; it will still need some clean-up work.  We will cover that in our next blog post.  Until then, play with the program and see what happens when you change things in the program.  Note that the sound statement has three parameters: the first is the pin on which you want the sound pulses to appear; the second is the duration (actually, it is the number of pulses — it will change depending on the tone;) the third parameter is the tone (again, it is not really the tone, but rather the delay between the pin going high and low.)  Take the numbers that I have presented and play with them to get a sound that you like.  Also, since three minutes is a pretty long time when you are experimenting, you will want to change the delay time in the wait statement.  I used five seconds, so that it still seems to be a timer, but it is not a painful wait. Just make sure to put it back to three minutes before we continue next time.

Until, next time – keep on learning.

Introduction to Microcontrollers

I want to introduce you to our newest product: the Introduction to Microcontrollers book and kit.  This set was designed in answer to the question, “how do I get started in microcontrollers?”  This question comes up pretty often in electronics, computer, microcontroller and robotics forums (and off-line, any time that the subjects come up.)  The best way to learn something is to dive right in, and get started; but you will have lots of false starts if you don’t have a guide for the exploration.

You will get a text book, written with total beginners in mind.  The nearly 100 pages include text, sample programs, quizzes and their answers.  You also get a small, simple development system.  This is a 2″ x 2″ Printed Circuit Board (PCB) with an Atmel ATtiny2313 microcontroller, a programming interface, a power connection (able to power the board from the programming interface or a battery, which is included,) and several Input/Output (I/O) devices.  Each I/O pin on the microcontroller, and each I/O device, has a female connector so that you can plug short jumper wires between them.  This allows you to easily connect the I/O devices directly to the microcontroller.

This book starts off by giving a good working description of a microcontroller, and introduces you to the actual controller that you will use for the course.  The second chapter describes programming, and walks you through installing a very powerful programming language for the microcontroller.  In the third chapter, you will actually build the simple development system of your own (all of the parts, including the printed circuit board [PCB] are included in the kit,) as I described above.

The rest of the book (an additional four chapters) are dedicated to getting you started in connecting devices like LED lights and pushbutton switches and programming your microcontroller to do what you want.  I made sure to go over each and every single line in the sample programs, so that you understand what (and how) everything works.  There are many samples included, with directions on how to modify each one to do what you want.

Coming up, we will be presenting a  series of short projects that will expand your knowledge with the Tiny2313 Experimenter System.

We are currently having an introduction sale on this set, for the rest of this month, we are offering the book and kit for only $19.99, that is 33% off the regular price.

Tiny 2313 Experimenter’s Board

There is a new project on which I am working.  For years, I have been taken with development kits.  Since money has always been pretty tight, most of my interest has been in the lower-cost kits.  Also, as a teacher, I have worked for decades to try to teach beginners about electronics, robotics and computers (our tagline reads: Helping to Build a Better Engineer.)

This new project is a very low-cost dev kit to introduce students to microcontrollers using Atmel’s low-end ATtiny2313.  This is a chip that I often find myself choosing when I need a low-cost controller for a project.  The kit is designed to provide much of what an engineer needs to create a new project.  There are pushbutton switchers, LEDs, connectors for servo motors and a speaker.  The board even has a light detecting phototransistor and a thermistor (I may have gone too far with that, since the 2313 has no real analog input – we shall see about that in beta testing.)  All of this fits in a tiny 2″ by 2″ PCB and can mount on a 4-cell AA battery box (with room to spare.)  The target price for this board is around $30-$50, with a beginner’s introduction text included.  There may also be an offer for the bare board for those who would like to roll-their-own.

Basically, I wanted something that is portable, like my Pocket Development Kit (,) and with all the peripherals needed to get started and learn.

Here is a picture of the Tiny2313 Experimenter’s Board, as it currently exists:

As you can see, the board uses a standard 10-pin STK-500 programmer.  There are many of these around, and I am currently evaluating one that I may be able to offer for under $10.  Also, since the STK programmer provides +5V, there is a jumper-switchable option to power this board from either an external battery (or power supply) or the attached programmer.

There is a reverse-polarity protection diode in-line with the battery input.  Yes, this will drop the input voltage by about 0.6V, but the Tiny2313V works just fine at those lower voltages.  This will affect the analog parts of the system, but that is something that I am still considering (also, we have a ‘X61 equivalent in development – the ATtiny26 family has several built-in real ADC (Analog to Digital Convertor) inputs on-board.

One thing that has yet to be determined is whether this is OK, as is.  With the Tiny2313’s analog comparator inputs (rather than true analog input,) the analog devices are only useful if the board has (or has access to) DAC (Digital to Analog Convertor) such as an R-2R circuit.  One change, consideration is whether to drop the servo motor connectors and replace them with a DAC, or to keep the servo interface.  This would lower the board’s value to robotics, but provide better analog capabilities.

Another possibility is to include a tiny breadboard and the resistors to create a simple R-2R DAC.  This would tend to lessen the all-included intent of this design – I really wanted something tiny that has everything needed to get started.  What do you think about these possibilities?  I am most interested in people who are wanted to just get started, or have taught these types of classes before.  Let me know!