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 (http://www.wrighthobbies.com/product.php?productid=62&cat=16&page=1 – Eddy was thinking about offering the base plates separately, write to him and ask him about this,) but you could use just about any

This is actually a cutting board which was included with a cheese & cracker gift set purchased years ago. It will make a nice little development kit base.

This is actually a cutting board which was included with a cheese & cracker gift set purchased years ago. It will make a nice little development kit base.

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.

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 2313ES Exp-1(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 Gound, 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 2313ES Exp-2to make sure that everything is wired up properly. You can use a simple “blinkenlight” (http://www.instructables.com/id/Ghetto-Programming%3a-Getting-started-with-AVR-micro/#step6 – 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 2313ES Exp-3+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 replacing 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.  2313ES Exp-4Take 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 2313ES Exp-5keep 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.

2313 ES

The 2313 Experimenter System

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 Toothbrushing Timeradmonition 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 2313ES - LED & Speaker Connectedshort jumper wire from the the second from the right-most hole (or pin) on the Tiny2313 socket, labelled 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: http://files.granzeier.com/Downloads/Toothbrush.bas.  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.