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Along with the photos on the google page, there are two different schmematics of how the board is laid out.  The first one is pretty simple and kinda 'dirty'... but the second one is a lot cleaner (it is the last photo... basically a JPG render of VISIO). 

I will try what you have posted... thanks a TON for your time and input!!

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The changes made did change the pattern output, but it is really different.  If I do
Code:
unsigned int outputpattern = 0xaaaa
I do get an every other column (but not pixel).

and the
Code:
=0xff00
displays a 'block' that slowly dissappears in the middle.

Weird, eh?
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I do get an every other column (but not pixel).
Yes well that is because you have not supplied a schematic so it was not clear what that shift register was driving.
To get an idea of a matrix look at this page:-
http://www.thebox.myzen.co.uk/Workshop/LED_Matrix.html


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displays a 'block' that slowly dissappears in the middle.
Weird, eh?
No it just reflects the way you have wired it up, in other words what signals control what physical position of the LEDs. You can correct it in the wiring or by scrambling the bit pattern you feed it.
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Alright, we used a program called ExpressPCB to draw this... don't shoot me, as I'm not an electronics person smiley ...  but, this is a really big PDF (size wise, not file wise).  https://docs.google.com/open?id=0B1fuI6Mh8iscLXFjMnNBdWhyb1k

What you can see is that there are seven TIP42C transistors that feed each row (and it appears that it pulls to ground).  There are two chips, the HCF4094 and teh ULN2003 that are shift registers. The Arduino hooks into the first HCF4094 chip, which then shifts the data down. 

The power supply / driver board was already built into the whole system.  We are just using the power to drive the board, and slid the Arduino into where the signal comes out of the original board. 

Hopefully all that makes sense.  Thank again, for your time and input! 
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I am sorry I don't see how that can ever work.

You seem to have 4 LEDs connected in series with only a 5V power supply. There is not enough voltage to turn 4 LEDs on.
Secondly you seem to only have two transistors.

Did you read that link I send you before about an LED matrix?
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Yeah, there are four of them in an array.  We cut the voltage down, cuz we are only running one of four panels... when we do that, if we don't cut the voltage, we end up smoking our arduino.  There are 7 transistors, not 2... just ran out of room to draw them all in.  Basically, they just repeat down the rows.  I can draw them in, if that would be better. 

I did look at the matrix website, but I'm still confused... ugghhh... not sure why it has to be so confusing smiley

Thanks again for your time and input!
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When I remove the resistor, I get about 20 volts... my meter read about 19.5, so I'm making an assumption that it 20v going to the transistor.  

Our setup is very similar to your column scan on your site.  Thank you for posting that out there for us.

Thanks again for your input and time... I really appreciate it!

EDIT:
I redid the PDF to include all 7 transistors and updated the voltage to 20.
https://docs.google.com/open?id=0B1fuI6Mh8iscaWkxYldkX1RFNzg
« Last Edit: June 01, 2012, 10:26:45 am by rossbr » Logged

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Yes that circuit will fry your arduino and not actually work correctly. This is because you will get a voltage greater than 5V on the arduino outputs. This will damage your arduino. You need to put the resistor values in the schematic. You probably need to turn the PNP transistors on with a driving NPN transistor.

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When I remove the resistor, I get about 20 volts
What resistor?

You need to indicate which is the emitter and which is the collector on the transistors.
Any chance of actually posting the PDF instead of where you post them. You have to have an account to see those and I object to google gathering data on me. Just click on the additional options triangle under the reply box.

To light up an LED you need to put one of the pins 2 - 7 low with the rest high. Then any value sent to the shift register will light up all the LEDs on the line with the power applied to it. That is the one with the logic low on the transistor.
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Yeah, we found that after our first Arduino, that you can only have up to 5 volts smiley-wink ... the second one my kid accidently touched the wires together and that one died.  At $40 a pop, this project has gotten kinda expensive.

We talked with a guy and he told us we could put a resistor on the main power feed that goes from the driver board to the arduino.  And then he suggested that we put resistors between the base of the transistors to the arduino pins (which is the same thing that you have on your column picture).  The base pin of the 7 transistors all go to pins 2 to 8.  The Emitter and Collector are still soldered to the OEM driver board, and the Emitter goes to the power, and the collector goes to the LED.  I will admit that I have no idea if that is the way that this should be setup; but that was the recommendation made by an electronics person.... so we just went with it.  

We used 330 Ohm resistors from the transistor to the ardino connections.  

EDIT:
Sorry for not attaching directly here before... I never clicked the 'additional options' button to see there there was an attachment option.


* ExpressPCB.pdf (145.09 KB - downloaded 5 times.)
« Last Edit: June 01, 2012, 12:34:28 pm by rossbr » Logged

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It often amazes me that people attempt to build something without a schematic. If you built what you have drawn it would melt. Try this:-
Reading a schematic
http://blog.makezine.com/archive/2011/01/reading-circuit-diagrams.html

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We talked with a guy and he told us we could put a resistor on the main power feed that goes from the driver board to the arduino
For what purpose? That sounds like bad advice.

Quote
And then he suggested that we put resistors between the base of the transistors to the arduino pins
Yes that is good advice. BUT - the base is also going to +20V through another resistor, it is that which is damaging your aduino. Even if it is not fried yet it will be.

Quote
I will admit that I have no idea if that is the way that this should be setup;
It sounds right, so why have you not drawn it like that?

Quote
are still soldered to the OEM driver board,
OEM stands for Original Manufacturer Equipment and it simply means some one bought it from a manufacturer and stuck their name / brand on it.
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That is the way it is... this is a premade LED sign that we do not have any other way of controlling.  I think it was made by data corp, which is no longer in business, and there is no more support for.  So, we have 'hacked' the sign to control via arduino. 

I guess I'll just use the arduino for some other project... I give up!

Thanks for your time and input, though!!

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Look at reply #19 on this link:-
http://arduino.cc/forum/index.php?topic=55311.15
It shows you how to correctly drive a PNP top switching transistor with an NPN transistor. Note that where it says 7V you can connect it to 20V. Then it will be safe to use.
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