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LED Dot-Matrix Displayby pinski1 on March 13, 2006

Table of Contents

intro:   LED Dot-Matrix Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

step 1:   Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

step 2:   PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

step 3:   Get the Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

step 4:   Soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

step 5:   Neaten it up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

step 6:   Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

step 7:   The finished thing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

step 8:   Improvements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

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http://www.instructables.com/id/LED-Dot-Matrix-Display/

intro:  LED Dot-Matrix DisplayThis is a simple HOW-TO make your own personalised LED Dot-Matrix display. I will be adding the complete program with an explaination to light the LEDs with. It's alsorather hackable, you can change it to suit yourself.

I decieded to make my own dot matrix display because they look cool, and none can be found in blue, which is the best colour, so I decided, may as well make it myself.

Image Notes1. This LED shouldn't be on, not at all, oh dear, debugging to follow...

step 1: PlanThe first task is to plan the project.

I built the cuircuit on Eagle so I could see the connections and test the LED matrix. It also enabled me to learn how to light the individual LEDs.

First thing to do is to add all the support stuff for PIC, so I need power supply, download socket and reset. I also need to arrange the outputs in simple to use rows. Thisdefined the size of the PCBs so I spent as much time as I could reducing the size until I couldn't get it any smaller.

The next step was to place the 20 LEDs in the dot-matrix, connectign all the anodes in columns and all the cathodes in rows. This is impossible to do without using linkwires unless your using double layer board or double sided board. I wasn't so I will be using link wires.

Image Notes1. The display itself. In this case 20 LEDs arrayed in a matrix with 4 columns and5 rows.

Image Notes1. This is the connector for the top. All the positive columns will connect up tothis.2. This is the side connector, all the negative rows will connect to this.

http://www.instructables.com/id/LED-Dot-Matrix-Display/

2. The side connector, all the negative rows connect to this, which should then beconnected to the side connector on the controller board.3. This is the top connector, all the positive columns are connected to this. Thisshould then be connected to the top connector on the controller board.

3. This is the download socket, it will allow you to re-program the PIC while it isstill attached to the board.4. This is the PIC. I am using a PICAXE18X, for more details look at step 2.5. Because it needs to be powered by something, and PICAXEs like 5v, andhate 9V.6. The reset for the PIC in case it hangs or gets a little confused.

step 2: PCBWell it needed to be made some how.

I designed the PCB on the school computers, which had PCB Wizard 3. Great piece of software, very easy to use but still very powerful. Unfortunately this means while Ihave the PCBWiz3 files, I don't have them in any other format, and the only pictures I have are the photo-etch masks, always good practice to wrap them up in the photo-etch mask paper for later use, or just documentation. Unfortunately they scanned in rather badly.

However as I redesigned the circuit on Eagle, I've gone and re-made the PCB.

Image Notes1. The display board, you can see the long pads where I intend to surface mount the link wires.2. The controller board, there are going to be many link wires, and lots of cleaning up as the tracks will probably come out touching. The downside of miniturisation.

step 3: Get the PartsOnce you know what your going to do you need the parts.

I used:

20 Diffused Blue LEDs1 PICAXE 18X Microcontroller1 serial socket1 22kOhm resistor1 10kOhm resistorlots of black multicore wirelots of red multicore wire

I used a PICAXE PIC as I've used them in school, they are very simple. I find them very simple to program, and then download the program to. PICAXE BASIC is ofcourse the only PIC language I know as well, so that limits them. They are meant to be quite easy to find, although in the UK you can just go to

Rapid Electronics - PICAXE

PICAXE manual - It is a .pdfPICAXE chip data - also a .pdf

I bought the LEDs at the same time, now as I was going for a blue dot-matrix these were my choice, and I paid for that, 48p per LED, so £12 for the whole lot, it wascheaper to buy in a pack of 25. Of course if your going make it you can use what you want, although to use my PCB layouts you'll be wanting a 5mm package.

I needed the 4k7 Ohm resistor for the reset, unless the reset pin (pin 4) is pulled high by the 4k7 ohm resistor then the PIC will constantly reset, which is bad.

I used the stereo socket, 10k ohm resistor and the 22k ohm resistor for the download socket, this means the whole unit is self contained, which is very handy. Alsoprevents the PIC being ruined becasue I keep having to pull it out and eventually end up snapping the legs off, what a way to waste £4.75...

I had the PCBs etched at school so they were essentially free. However we use poor quality boards so the tracks can be pulled off quite easily, but I didn't think thatwould be a problem, not yet at least. Oh was I in for pain.

http://www.instructables.com/id/LED-Dot-Matrix-Display/

Image Notes1. LED Matrix PCB2. Controller PCB3. Solder, how else are we going to attach the componants to the PCBs ?4. Parts, on a black foam, sorry :(5. 25 Diffused Blue LEDs @ £0.48 each, eek !

step 4: SolderingOnce you have the parts, it's time to connect them all together.

The first board I began soldering on was the display board. There were a number of reasons, it looked the most boring, it would be great fun to play with once I'd finished,and it would be boring, wait, did I mention that ?

So once I'd cleaned up the tracks with some wirewool I began cutting and attaching link wires. These were damn fiddly and quite hard to make and then fix in place, so inabsence of a dutiful ceramic-fingered assistant I used sellotape, which lead me to the discovery, not for the first time, that burnt sellotape is nasty nasty stuff.

Once this was complete I started soldering the LEDs, I started from the top and worked my way down doing them individually, until I got bored and started on whole rowsat once. Towards the end it got quite difficult as the LED leads stuck out quite a way. Once all 20 LEDs were soldered, I attacked the back and snipped off all those peskyleads as far down as I could. And true to my earlier thoughts grabbed a spare 6v battery pack and battery clip and began running the wires up and down the connectionslighting up columns. This looked pretty good on it's own, infact, the rest of the project may have been worth it just for this look. Of course for some strange reason wholerows were lighting up together but at this point I didn't quite notice...

Image Notes1. This is the back of the main board, here you can see the PCB layout, not tomention my beautiful soldering.

http://www.instructables.com/id/LED-Dot-Matrix-Display/

Image Notes1. The solder in the background2. PHEW all 20 LEDs attached, complete with 8 mini link wires surface mountedon the back for neatness.3. The legs of the LEDs poking out the back just before I snip them off.

Image Notes1. The top connector on the controller board.2. The LEDs.3. The controller board.4. The top connectors on the LED board. These are connected via the red multi-core wire to the controller pcb.5. The side connectors, connected together with black multi-core wire.

http://www.instructables.com/id/LED-Dot-Matrix-Display/

step 5: Neaten it upOnce you've soldered the boards together it's time to neaten them up. There are a number of things you can do.

Remove excess flux:Flux helps the solder flow and make good contacts however it does look pretty nasty when dried and is best getting rid of for that beautiful look. The best way to do this isyou dab at the board with a rag which you've soaked in acetone. Where abouts would you get acetone I hear you cry ? Well you can get it some art shops, you can alsobuy it at some boating/marine shops as a part of the fibreglass range, however the best source is in fact cheap nail varnish remover. So head down to your nearest cheappharmacist and start looking for the cheapest nail varnish removers. I'm talking about 49p for 200ml, my past experience shows that this comes in pink bottles.

Clean up the edges of the boards:This is as simple as sanding the edges of the board down so that they're smooth and flat. It's also quite nice to round the edges.

And that's is about it for the moment.

Image Notes1. The negative side connector wires, which are a little close to the edge of the pcb.2. The power cables dissappearing off the photo.3. The download socket.4. Cut and sanded PCB edges, makes it look pretty, doesn't hurt your hands, oh and it could almost be professional.5. LEDs galore !!!6. Signs of heavy use ...

step 6: ProgrammingSo you've made it, you've plugged the battery in, but wait, no, it's not working, or maybe you just have to program it ...

Ah that'd be a good idea. Becasue of my forthought, I have a download socket already on the PCB, so, just whack in the download cable, plug that into a serial port onyour PC, get Programming Editor, and get coding!

Of course it helps if you've programmed a PICAXE before, I've had about 4 years experience so far, GCSE and AS/A level.

The first thing to do is to type:

main:

goto main

This just sets up the PICAXE for the program, put the important code between the main and goto main, I do this so I don't forget to do it later. The next task is to set theoutputs, which pins do you want high, and which low. The long and time consuming way is to go:

high 1high 2high 3

low 1low 2low 3

Or you can be cool and set the states all in one line with:

let pins = %00001110

let pins = %00000000

This works by giving each pin a specific digit, so pin 8 is the fist digit, pin 0 is the last digit and so on. We also need to be able to put a time delay in there so the pins areactually left on long enough for the LEDs to light. There are 2 main PICAXE waiting commands, wait and pause, wait 1 waits for 1 second, where as pause 1 waits for

http://www.instructables.com/id/LED-Dot-Matrix-Display/

1uSecond, which is what we need.

Those inclined to nit picking will have noticed that there are only 8 pins on the pins=%00000000 command. Yes, the ninth output on a PICAXE18X is infact the serial outpin. This requires a completely new piece of code to set.

poke $05,%00000000

poke $05,%00001000

I'm not too sure why this works, or why it's nessesary, but I did get it from the friendly people at the PICAXE Forum

So putting all that together gives us:

main: ' Letter Alet pins = %00011000 'poke $05,%00000000 ' Set SERTXD line lowpause 1 'let pins = %00100101 'poke $05,%00001000 ' Set SERTXD line highpause 1 'let pins = %01000101 'poke $05,%00001000 ' Set SERTXD line highpause 1 'let pins = %10001000 'poke $05,%00000000 ' Set SERTXD line lowpause 1 'goto main '

That should display the letter A on you dotmatrix display

Image Notes1. Handy notes, namely the difficult to remember commands and PICAXE notes.2. The letter B in code.3. The PICAXE program editor, unimaginatively named, Programming Editor...4. Good music, this is essential.

step 7: The finished thingHere it is displaying a letter A.

And the second image is of a letter B in the dark, these are diffused blue LEDs with a freshly charged 4x AA 2500mAh battery pack, quite bright. But not so bright as soyou can't see the display, perfect.

http://www.instructables.com/id/LED-Dot-Matrix-Display/

Image Notes1. This LED shouldn't be on, not at all, oh dear, debugging to follow...

Image Notes1. This shouldn't be on, oh dear ...

step 8: ImprovementsIt works, so now what, bask in the glory of a complete, and working project, no, not for a second. How can I make it better, how can I make it cheaper how can I make itCOOLER !!!

Well here's a few idea's that have been bouncing around my head.

SMD LEDs, okay, what if the leds were much smaller, that'd drop the total thickness of the project by what, 5mm, smaller is better. Plus SMD is so much cooler looking,geek +5.

SMD PIC, whoa, more SMT goodness, geek +10 at least, okay it'd be un-removeable, but you can still download programs to it while it's on the board. Oh and it'd dropthe thickness of the project, at the back by 5mm (don't forget the download socket though).

Professional PCB manufacturing, well, how easy woudl that be, sure it'd cost a bit, but it would mean the boards are perfect, well, as perfect as you made them. You alsoget to play with fun functions like multi-layers or double sided boards, imagine a double sided PCB, you wouldn't need 2 seperate PCB then. Add to that SMDcomponants like resistors, LEDs adn PICs and you've got a very classy, but expensive board. Here's a list from CadSoft, the people that made Eagle, PCBManufacturers .

Larger display, most displays are 5 by 7, mine's a 4 by 5, so making it larger would open up a whole new range of display options. Of coruse you'd need more outputs, Ionly had 9 available, but if you were to use a PICAXE28X you have up to 17 available outputs, thats an 8 by 8 display. Nice. However if you move away from PICAXEsonto other microcontrollers I'm sure there are ones with different output pins. Another option is to Charlie-Plex the outputs, although you'll need to be able to set outputpins as inputs to get that working. I believe this is possible with most non-PICAXE PICs, especially Arduino's.

Hopefully once my website ( TheDarkPlace or just The Dark Place) is up and running, I may be able to sell kits of the 4 by 5 display, with a few options, such as 2seperate boards, 1 complete board and 1 complete board with 2 layers. That however depends on how many people like it.

Or you can just email me at:

at :link is invalid

pinski1 gmail.com

Here's some pictures of the layouts.

http://www.instructables.com/id/LED-Dot-Matrix-Display/

Image Notes1. The display.2. The download socket.3. The PICAXE.4. The reset.5. This is the two earlier boards made into one. It is much larger, but does simplify theconstruction process.6. The power.

Image Notes1. The power.2. The dowload socket.3. The reset.4. The PICAXE chip.5. The display.6. This board uses two layers (the blue tracks and the red) whichtotally removes all the link wires it also reducesthe board size.However as it is 2 layer it will cost a bit more.

Image Notes1. This is just an updated version of the circuit schematic. I've gone and removed theconnectors and joined the relevent tracks together. Note: there may be a fult with the VSS/VDDpins.

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Comments50 comments Add Comment view all 106 comments

 gsmtaoufik says:  Dec 15, 2008. 4:56 AM  REPLYnice job thanks !!!!!!!!!!!!!!!

 pazakit says:  Jan 27, 2007. 12:38 AM  REPLYwhat if ?? i make it 5x5 led is it possible??? because you cant write a letter m,n,z in 5x4 !!!!

 pinski1 says:  Jan 27, 2007. 2:40 AM  REPLYA 5x5 LED display would require 10 outputs. I only have 9, such are the limits of PICAXEs. However, if you wanted to use an Atmel or an PIC you mayfind more like 12 outputs in an 18-pin package. I know that an Arduino has 13 outputs.

 yourcat says:  Dec 5, 2008. 3:17 PM  REPLYA PICAXE 40X2 could theoretically have 31 outputs...

 Bongmaster says:  Jun 17, 2008. 2:40 AM  REPLYwhat resistors would u use on a 5x5 matrix (2.3v 30ma LEDs)?

I'll be connecting up to an arduino so it will be getting 5v from that.

 yourcat says:  Dec 5, 2008. 3:15 PM  REPLYSlight correction: some PICAXE models (both 08s, 28s and 40s X or better) can input or out put on some pins. An 18X wouldn't do charlie-plexing, but thereare some that would.

 slimguy379 says:  May 25, 2008. 8:48 PM  REPLYnow all you have to do is make this small scale with 3mm leds and turn it into a belt buckle! that would be awesome!!

 chinnokker999 says:  Mar 14, 2007. 7:21 PM  REPLYHey i was wondering how you'd make a "T" with this setup... Since there's an even number of horizontal rows, you wouldn't be able to center the vertical linecoming down from the top of the "T"...

 pinski1 says:  Mar 15, 2007. 2:39 AM  REPLYAh, you've found the fatal flaw...

Because of my limit on size and the number of outputs, I could only have a 4x5, not the standard 5 by 7, but it does the job, and I like it.

 thermoelectric says:  Apr 13, 2008. 6:37 PM  REPLYCould You make another one that is 5x7?

 pinski1 says:  Apr 13, 2008. 7:12 PM  REPLYI could, but I won't. The chip I used above, the PICAXE18X doesn't have more than 9 outputs. Ideally you'd need one with 12 outputs, or somefurther ICs to add to the previous 9 outputs.

I'm not making another one, because I really don't see the point there are other things which I'm yet to do, things with ethernet and X10.

http://www.instructables.com/id/LED-Dot-Matrix-Display/

 Ankush says:  Oct 30, 2007. 10:24 AM  REPLYI was wondering, can you display a sinusoidal wave-form in ur 4x5 dot matrix. I know u r using it to display alphabets & numbers. But i believe thatyou cannot have a sine-wave on this type of display device.........as un-neccesary LEDs would glow.

 Ankush says:  Oct 30, 2007. 10:15 AM  REPLYWell you could display a T with a 4x5 dot matrix.......just that it is the small T...."t"!!!!

 pinski1 says:  Oct 30, 2007. 11:51 AM  REPLYI'm afraid you can do neither. The resolution is far too small to display a capital T let alone sin waves. The LED's wouldn't unnecessarily glow.

 Ankush says:  Oct 31, 2007. 12:04 PM  REPLYI actually meant small "t".....unless ur looking to display only capital alphabets. Actually if you draw the schematic diagram of your 4x5 matrixyou will find that to display only a diagnol 3 LED's , unneccesary 3 other LED's would glow, try it & tell me if thats not true!!.

 pinski1 says:  Oct 31, 2007. 12:14 PM  REPLYif you read the explanation, you'd realize it's is not true...

The technique is called multiplexing. it's where you switch on all the LEDs on in a column or row at once, then turn them off and move tothe next row, if you do this quickly enough, they eye doesn't see these changes and instead just sees lit LEDs. Try googling multiplexingfor more information.

 Ankush says:  Nov 2, 2007. 1:36 PM  REPLYOk, yeah thats right. But a standard 5x7 matrix has a problem with diagnol LEDs lighting up....& i mean continuosly ON. Its allbecause its connected that way. Maybe a circuit diagram would show you what i mean.

 thermoelectric says:  Apr 12, 2008. 3:20 AM  REPLYWowDid you write enough thingsThis is great

 stasterisk says:  Apr 3, 2008. 5:01 PM  REPLYDid you use any transistors?

 pinski1 says:  Apr 3, 2008. 6:01 PM  REPLYNope, none, have a look at the schematic in the first or last step.

 Assassins says:  Mar 26, 2008. 1:57 AM  REPLYhello, can anyone help me? which software i hv to use if i want to write the program codes?

 coolketan95 says:  Mar 28, 2008. 1:22 AM  REPLYYou can use basic stamp editor

 pinski1 says:  Mar 28, 2008. 2:33 AM  REPLYWell, this would defiantly NOT work. The BASIC Stamp editor is for stamps, not PICAXEs. To do the programming for this you need to use ProgEdthe programme editor for PICAXE, you can find it on the PICAXE website.

PICAXE ProgEd

 coolketan95 says:  Mar 28, 2008. 1:21 AM  REPLYThat dosent work

 pinski1 says:  Mar 28, 2008. 2:30 AM  REPLYWhat doesn't work, you'd need to be exact...

http://www.instructables.com/id/LED-Dot-Matrix-Display/

 imarzouka says:  Mar 22, 2008. 10:38 PM  REPLYhttp://ledcalculator.net

 Assassins says:  Mar 18, 2008. 8:56 PM  REPLYcan u give me the C programming codes of urs? cuz i think i need to learn it first. my email is evil.nang@gmail.com. thanks a lot.

 Assassins says:  Mar 18, 2008. 8:47 PM  REPLYhi pinski1. i'm doing the 4*4 LED matrix. i hv to do both BJT board and FET board. the program is written by visual C?? then use AVRstudio4 to convert? mycircuit is exactly the same wif the one frm this website. http://www.siwawi.arubi.uni-kl.de/avr_projects/matrix44/index.html

 russ_hensel says:  Mar 12, 2008. 12:01 PM  REPLYFor a similar project but for those of you who like PIC midrocontrollers and an 8 x 8 display ( or want more ideas on this topic ) see:PointLess LED Array at http://www.opencircuits.com/PointLess_LED_Array

 gogorock says:  Feb 26, 2008. 10:24 PM  REPLYAm I seeing things!?I build the 5 rows by 7 cols LED matrix.When I connect common node for col 4 to +3V,and common node for col 5 to ground.I see LED at row 2 by col 4 lites up!@,@ Any ideas? Thanks.

 technopenguin says:  Jul 16, 2007. 10:07 AM  REPLYYou should have spacers and screws to hold the board together.

 kidengineer says:  Jul 5, 2007. 7:38 PM  REPLYcool

 tridens says:  Jun 21, 2007. 2:44 PM  REPLYWhat do you think? I was thinking of using a matrix grid in the construction of a programmable license plate. Instead of LEDs, I'd use a lot of small coils ofwire acting as electromagnets. Then, you'd just have to get some iron filings and blow them on the plate and viola!! - whatever arrangement wasprogrammed into the matrix would be visible b/c of the filings sticking to it. Thoughts??

 iloseonpurpose says:  Dec 13, 2006. 6:21 PM  REPLYwhat school do you go to?

 pinski1 says:  Dec 13, 2006. 6:34 PM  REPLYI went to a Grammar School near London in the UK.

 mattbeddow says:  Jun 13, 2007. 4:49 PM  REPLYSo what grammar school did you go to because i go to one outside London in the uk. its in a town called REading if you know it.I also have a question, surly if i make JP3 pin 1 high and JP4 pin 1 low to turn the top left one on and i make JP3 pin 2 high and JP4 pin 2 low to turnon the LED to the bottom left of the top left LED on then the top left 4 LEDs will all come on when you dont want them to? If you need this explainedbetter then just post a message on my orangeboard or email me or something (its matt.beddow@gmail.com) dont add me to msn cos ill just blockyou (nothing personall, i do it to everyone i dont know)

 macmaniac says:  Feb 19, 2007. 4:07 AM  REPLYI also go to a school in the UK with extensive electronics resources. I have used their software (PCBWiz) to make pcbs before, and it is very good. Iuse the 'toner transfer' method for etch resist and buy all my components etc from Maplin. If you're interested, they sell double sided boards.

 pinski1 says:  Feb 19, 2007. 4:36 AM  REPLYPCBWiz is fairly limited. But easy to use, so it's good for a school. I now use Eagle, http://www.cadsoft.de/ There are quite quite a few tutorials onhow to use it on this website.

Maplin are not very good either. They are VERY expensive. I now use RapidElectronics. http://www.rapidonline.com/

As for double sided boards, because I was doing this at school, I did not have double sided board to hand, and did not want to make the layoutmore complex by using it, I did not use it. It works fine with out it, so I'm quite happy.

So please STOP with this "why don't you just use double sided board" comments. I didn't, it's easier not to, and it is now done. Oh and at the time

http://www.instructables.com/id/LED-Dot-Matrix-Display/

I had NO idea how to do double sided board in PCBWiz.

 led235 says:  Nov 3, 2007. 6:59 AM  REPLYI recommend Electronic Goldmine!!!! They Have Incredibly LOW prices!!! (www.goldmine-elec.com)They give away free stuff if you order like $20.00 or more!super discounts!!!NEW ARRIVALS

WEB SPECIALS

SALE ITEMS

WIDE SELECTIONOF PARTSfree catalogs!!!Giant Display Assortment for only $5.00 it contains over 20 pieces!their brightest led only cost .59 cents!!!*****you must see their breadboards section!!!*****

 mickeymao says:  Apr 12, 2007. 8:55 PM  REPLYNingbo Flying (http://www.nb-flying.com) can provide similar items

 macmaniac says:  Feb 20, 2007. 12:25 PM  REPLYAlmost immediately after writing the previous comment, I discovered rapid electronics. Their prices are amazing. The 4017 is 4 poundscheaper! I'm definitely going to use them again

 pinski1 says:  Feb 20, 2007. 12:45 PM  REPLYAh, don't forget eBay, and of course the chip manufactures. They sometimes give free samples.

 zachninme says:  Jun 5, 2007. 5:25 PM  REPLYSorry this seems so random, but...

If you still have it, can you photograph both where to connect the jumpers on the LED board, and the components on the controller board? I was going to dothis myself :DThanks.

(This is on your LED Dot-Matrix Display Instructable, if You are receiving an email)

 pinski1 says:  Jun 7, 2007. 2:48 AM  REPLYI'm afraid this project's packed quite tightly away somewhere, you could try figuring it out using the circuit diagrams I provided, other than that, sorry.

 salmanmufti says:  Apr 19, 2007. 12:48 PM  REPLYhiim student of bio medical engineering and i have assigned a proj to display a counter from 0 to 9 on dot matrix through a switch

means whenever i press a switch it counts and stop untill the switch is pressed next time i have to make hard ware also and by using atmel 89c51microcontroller and 8x8 dotmatrix

plz help me i have to submit it after 3 days plz give me coding and circuit diadram plzzzzzzzzz im counting on u plzzzzzz

 sammy_pic says:  May 29, 2007. 9:18 AM  REPLYi could help but its going to be using a PIC microcontroller instead. and i hope your assignment is not too late at this time. My e-mail isosafehinti5@yahoo.com

 jnkarrik says:  May 11, 2007. 3:34 PM  REPLYOMG a bomb!! Boston PD will be calling you shortly...

 James (pseudo-geek) says:  May 22, 2007. 6:21 PM  REPLYlol PDs are so paranoid. they think anything with lights and wires is probably a bomb. if I where gonig to bomb something, it would NOT look likeANYTHING electronic. people are stupid.

http://www.instructables.com/id/LED-Dot-Matrix-Display/

 mitxela says:  Feb 25, 2007. 4:54 PM  REPLYpinski1, you're my hero.

Would never have been able to finish my GCSE project without this article.

Is the half-lit LED a software problem? The LEDs on the row of the 9th output on mine sometimes seem to light up dimly when they're not meant to.

 ichbinbored says:  Apr 11, 2007. 2:34 PM  REPLYIf the problem is on output 9 its probably because on the PICAXE-18 series, output 9 is the serial output. It does this if the serial input (pin 3) is floating,so it thinks it is receiving a new program and sends out some signals through output 9 to check. These high frequency signals can light up the LEDs. Tosolve this problem, simply connect pin 3 to ground.

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