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Author Topic: Ping pong wih LED matrix  (Read 3203 times)
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Hey, guys, I need your help. I'm trying to make this: http://www.instructables.com/id/Pong-with-8x8-Led-Matrix-on-Arduino/

But... I'm completely stuck in this:

You can see the mess.

It's for a science fair in school. I'm not even an electronic newbie. I just found it cool and thought it would be easy. Firstly, it was hard to get the materials. And now, the software, even though it's not relating any problems, is not working. Please, help me!

I don't know if the picture can help you to help me, but I'll give any information you need.

The code is here: http://blog.bsoares.com.br/arduino/ping-pong-with-8x8-led-matrix-on-arduino
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Can you post the code you are actually using?

What happens? Do the LEDs change at all?
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Well, just one thing I will point out is that the original spec (http://blog.bsoares.com.br/arduino/ping-pong-with-8x8-led-matrix-on-arduino) uses a monocolor 8x8 matrix and you clearly have a bicolor one.  In addition, I see both colors being represented on your matrix.  Did you intend that to be the case?  Because you might simply have the matrix wired up incorrectly.  The pinout for your matrix will have 24 pins instead of 16 and if you use the pins numbers suggested on the spec page you linked, those are not going to be the correct ones for your matrix.  You will have to cross reference with the datasheet for your particular matrix to determine the correct pin numbers.
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Where is the resistors? You will destroy your arduino. In original post, blue led matrix, which is less destructive, compare to red leds, but wrong anyway.
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Nick Gammon, the code is here: http://blog.bsoares.com.br/arduino/ping-pong-with-8x8-led-matrix-on-arduino. Nothing happens with the LEDs.

JoeN, yes, I noticed this, but when I bought the matrix last year, I didn't find a monocolored one. I just wanna put the things working hahaha. I don't intend to make any modification in the code or something, because I really don't know about programming (in fact, I noticed that my matrix has pins left). I wanna focus on diodes and semiconductors in my science fair. After that, I'll sell the parts. So, which matrix do you think I can buy to get more chances of success? http://www.ebay.com/sch/i.html?_trksid=p5197.m570.l1313&_nkw=led+matrix+8x8&_sacat=0

Magician, I can't see any resistors in the original one (http://blog.bsoares.com.br/wp-content/gallery/ping-pong-com-matriz-de-leds-8x8-arduino/pong-with-8x8-led-matrix-on-arduino-3.jpg). Maybe these two wires alone? You're free to help me here, brother hahaha

Thank you all, guys!
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I don't intend to make any modification in the code or something, because I really don't know about programming (in fact, I noticed that my matrix has pins left).

You've got the wrong part. It doesn't work.
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JoeN, yes, I noticed this, but when I bought the matrix last year, I didn't find a monocolored one. I just wanna put the things working hahaha. I don't intend to make any modification in the code or something, because I really don't know about programming (in fact, I noticed that my matrix has pins left). I wanna focus on diodes and semiconductors in my science fair. After that, I'll sell the parts. So, which matrix do you think I can buy to get more chances of success?

First of all, a bicolor display can be made to work just fine.   But, the pins that you will wire will be different.  Bicolor displays are wired in a similar way as the monocolor display, it's just that they usually have 16 columns (8 for red and 8 for green) instead of 8 for one color and the same number of rows, 8.  So there are 24 pins instead of 16.  And the pin numbers for the particular column or row you are addressing will be different.  So you have to look at the wiring diagram for the example project, correspond each pin to the row or column it addresses, and then figure out the correct pin on your matrix for that row or column.  Just looking at the picture you suppied, I know you don't have the pins right (probably because you used the pin numbers on the example project) because you are showing both red and green columns lit when you really should have chosen pins for one color or the other (your choice, it does not matter), NOT BOTH.  Do you have the datasheet for the display that you are using?

This display has the same pinout as the one in the example project, but it is only 20mm which is not super impressive.  Nor is the price for what you are getting impressive:

http://blog.bsoares.com.br/arduino/ping-pong-with-8x8-led-matrix-on-arduino (see pinout)

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2132349_-1

http://www.jameco.com/Jameco/Products/ProdDS/2132349.pdf (see pinout on page 3)

I would check ebay and search for "60mm 8x8 matrix", choose the ones that are one color only and check the linked datasheets to see if it matches the example matrix.  I can't check eBay right now.  Then again, you have all the information you need to correctly wire the matrix you have.
« Last Edit: June 21, 2012, 11:27:22 am by JoeN » Logged

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JoeN, thank you so much! Now I made the right connections and this is the result:

http://i47.tinypic.com/dvlrio.jpg

But... the potentiometers are not working! I spin them and nothing happens.

The author of the project said he used 5K potentiometers connected to Analog IN 4 and 5, and that's what I did. But I don't know if I'm connecting them really correctly. And the resistors, are they needed?

Thank you once more.
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It looks like your pots are connected on the outside pins of the pot. You need to connect the middle pin and one of the outside pins.

A pot is a variable resistor with the middle of the 'wiper' connected at the center. When you rotate one way or the other the wiper moves in the resistor so that you get a different value on the two outer pins that add up to total rating for the pot (ie, it is a variable voltage divider).
« Last Edit: June 21, 2012, 06:32:44 pm by marco_c » Logged

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It looks like your pots are connected on the our=side pins of the pot. You need to connect the middle pin and one of the outside pins.

A pot is a variable resistor with the middle of the 'wiper' connected at the center. When you rotate one way or the other the wiper moves in the resistor so that you get a different value on the two outer pins that add up to total rating for the pot (ie, it is a variable voltage divider).

But I connected the middle pin:



Where should I put the other pins?
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It was hard to tell from the previous photo...
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Well, I just don't know what to do about the pots. And I don't know if it's normal, but the code is running automatically, without Arduino software.
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Can you take another photo of the whole layout? Your earlier photo did not show the pots connected to the analog pins.
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Quote
And I don't know if it's normal, but the code is running automatically, without Arduino software.

Can you explain this better? The compiler code dowloaded into the AVR processor will execute as soon as you apply power to the board. The IDE (is this the "Arduino software"?) running on your computer is not required for this to happen.

Are you able to write a small program to test the pots work properly as connected? Just read the analog value and print it to the Serial port so you can see if rotating the knob changes the value.
« Last Edit: June 21, 2012, 08:40:32 pm by marco_c » Logged

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I'd suggest you have a look at this tutorial:
http://tronixstuff.wordpress.com/2010/09/28/moving-forward-with-arduino-chapter-18-rgb-led-matrix/
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