next topic »

[Reply #15 on:]

I put resistors in rows, not in cols.
Is that make problem?  

Sharing one resistor among up to 56 leds is probably a bad idea because it would alter the brightness of the leds widely depending on how many of those 56 leds are on when that row is on.

[Reply #16 on:]

Maybe Arduino Scrolling 56x8 LED matrix and  Arduino Rolling Multi 16*16 LED Matrix Brick are twinborn brother at some idea. LOL

Arduino Rolling Multi 16*16 LED Matrix Brick :
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1273337857

[Reply #17 on:]

how would I change your code to use matrices who's columns are the anodes, rather than the rows?

Sorry for responding so late.
I may be mistaken, but I believe unlike 74HC595, TPIC6C595 can only drain into ground and cannot supply positive to the anode columns of your matrix.
There's probably a chip similar to TPIC6C595 that would work with your matrix, but I do not know what that is. :-(  

[Reply #18 on:]

Hi I am trying to replicate this just using the 74HC595. i have it working perfectly with one 8x8 module. My issue is I have added additional 8x8 Modules but the i cannot get it to output the the additional modules using this code. It just outputs to the first module over and over. i have changed the Bitmap array to reflect the additional modules but nothing has changed. Can someone help me as i am completely stuck.
Cheers
Chris

[Reply #19 on:]

Right i have managed to get this working (Kind of)... using hari's code I have one slight issue. as each charature crosses from one matrix to the next the first colum seems to stick causing an odd flashing pattern.

Take a look at the following Vid and you will see what i mean.


If anyone has any insight into this I would appreciate it, I am sure it is a code issue but i just cant get to the bottom of it.

Cheers
Chris

[Reply #20 on:]

Thanks everyone I couldnt have got this working without you......

I figured it out in the end it was a wiring fault. I have now complete the Sign.

[Reply #21 on:]

how would I change your code to use matrices who's columns are the anodes, rather than the rows?

Sorry for responding so late.
I may be mistaken, but I believe unlike 74HC595, TPIC6C595 can only drain into ground and cannot supply positive to the anode columns of your matrix.
There's probably a chip similar to TPIC6C595 that would work with your matrix, but I do not know what that is.

I use 74HC595 for both row and cols and use CA matrixes.
I invert the bit of the characters. It's works!

[Reply #22 on:]

The TPIC is the same as the 595 but it has higher current output. The code will be identical. There is another chip HEF4794 which is also a high power output chip but only drives 40ma.

The standard 595 chip will drive 1 LED per output fine but if it needs to drive more you're going to have to boost it's output.

[Reply #23 on:]

I have actually managed to get this to work now just with the 595's.

[Reply #24 on:]

I'm intrigued, can you post code for that? maybe a quick sketch of how the 595s are hooked up to each other as well?

[Reply #25 on:]

I have connected everything up the same way as hari but I used a 595 with transistors for the negative rows.

You can get the code i used at http://www.malyon.co.uk/chris-s-projects/arduino-led-matrix

[Reply #26 on:]

Hello hari,

wanted to say thank you, i borrowed a few lines of your code for my Arduquee project. Have a look:

[media]http://www.youtube.com/watch?v=DMQyje3y1hg[/media]

Had to modify it heavily because we designed our hardware differently and I used a tri-color matrix. I found your code after I already had the boards made and some of my own code written.  

The segments are modular and any length marquee can be built. I plan on making these into kits eventually, as a cheaper alternative to serial backpack boards.

[Reply #27 on:]

Hi everybody at the Arduino forum!

Hari, is your homepage down for good, or are you improving it?

I would interested in the "56x8ScrollingLEDSchematic.jpg" picture as I am doing this same project myself for school project. Need some help with the wiring as I am designing a circuit board for this.

Is there anyway you could send it to my email, if you still have it on your computer?

[Reply #28 on:]

Oh sorry about that...
I've added the schema to the end of the blog post.
http://g33k.blogspot.com/2010/02/arduino-56x8-scrolling-led-matrix.html

Good luck with your project!  It is a lot of work, but very rewarding.

[Reply #29 on:]

Thanks Hari!

This will be a huge help and I will give credit to you in the written report