3 different ways for diagram

slotcarz

Hi All..
I have attached 3 images of diagrams. Fig. 1 is from the MAX7219 doc., fig. 2 is from Jon Williams' tutorial and fig. 3 is from Steve Edwards tut. So I do not know which one I should or should have used. I wired it up following fig. 3 with one section and used Jon's code from his tut and the leds seemed to work except for all of them being lit while the code passed thru the leds. I decided that I needed to cascade them with the diagram from Max7219 docs and that is where I am at now. I have 4 of the 7 sections wired up and using Jons' code, it will not run the code thru the leds while they are powered up. Looking thru the max docs, it says to use a serial connection to set up the max7219 chips for cascading them.·I have wired· a test board but doesn't seem to be reading or doing anything with the chips. I had an old printer cable, cut off the useles end, traced all the pins to their colored wires to make sure I had the right numbers but still nothing. Maybe someone has some tips on using the max software for setting up the chips.

Is their a way to use the BS2 to access the chips to set them up in series? Or do I need to use my test board to set something up?

Sorry to ramble on but I haven't had the time to get this thing done. My wife and I are in the process of adopting a child from Russia and should be going there mid May hopefully.
Thanks again...
Jeff

Post Edited (slotcarz) : 5/3/2005 2:52:38 AM GMT

Chris Savage

Hello,

·· One connection is for 7-segment displays, the other is for matrix display.· What is the application you are using this in?· That might help determine the connections, since up to 8 7-segment displays can be connected to one MAX7219 chip.· Why would you need to cascade them?

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support
csavage@parallax.com

slotcarz

Hey Chris, I guess·I should have posted on this thread and not started a new one, sorry for the confusion.
http://forums.parallax.com/showthread.php?p=533016·- project in motion.


The max will run up to 64 seperate leds. To keep wiring as simple and clean as possible I created a bank of leds at 8 columns by 7 rows, 56 leds. I assumed that I needed a 7219 for each bank of leds. It eneded up being 6 banks of 56 plus a 7th at 14 leds.
Hope I'm not confusing you as I am confusing myself .

I would think that I created a matrix and would follow the matrix one as Jon has. I understood it as daisy chaining (cascading) the chips to allow the flow of data thru all the leds via the chips.

ok brain cramp... I gotta start dinner ... be back in a bit..

thanks
Jeff


·

Jon Williams

If you're only doing 64 LEDs then just one MAX7219 is required; the Digit lines connect to your columns (cathodes), the Segment lines to your rows (anodes)·-- since you have eight digit lines and eight column lines you can in fact control 64 discrete LEDs. On of your engineers (Jeff) put 64 LEDs around a picture frame and controlled them with a BS2 and the MAX7219.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Jon Williams
Applications Engineer, Parallax
Dallas, TX· USA

Chris Savage

Yes,

·· Starting a new thread did confuse me.· If you're running more than 64 LEDs, you will need to cascade (Daisy Chain) MAX7219s.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support
csavage@parallax.com

slotcarz

ok.. I am controlling 350 leds. I have put the digits on the·columns·and the segments on the rows. I guess what I am looking for is which diagram do I follow? And do I have to address? the chips for the cascade like it says in the max docs or does the programming thru the bs2 take care of this?


thanks for the replies...

Jeff

slotcarz

I contacted Maxim directly and the tech suggested·I had a wiring problem with the Seg and Digits. I switch them and the LEDs turned off and NOW I have a working display. So I will have to switch all the wires for it to run and thats about it for updates on this.

Post Edited (slotcarz) : 5/3/2005 2:55:18 AM GMT