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Topic: MAX7219 in daisy chain. How many decop capacitors I need? (Read 4 times) previous topic - next topic

Aaron_dyer

Ya I was starting to doubt myself...I have been reading this page over and over regarding cascading the max7219...

http://www.arduino.cc/playground/Main/MAX72XXHardware

Crossroads has been helping me, but I just can't get it to scroll anything on the matrices....


I think I'm going to switch up the wiring to cascade it like the playground has it...and then try to find some example code..or come up with something....

any example code reference would be great...

Just keep in mind, I'm using a Mega2560..

so SCK = 52

MOSI = 51

SS (LOAD) = 53

Riva

Grab the LedControl library http://arduino.cc/playground/uploads/Main/LedControl.zip if you don't already have it
and try the scrolling demo attached. It's written for a single 8x8 matrix running on an UNO but should work on upto a 24x8 matrix with little alteration. As it uses the LedControl library it bitbangs instead of using the SPI interface.

Aaron_dyer

Heres my latest update:


so I have cascaded them now...data out from 1st max7219 -> data in to next one....and so on for 4 of them to control the 32 x 8  (4 matrices..)

Its a tight enclosure...I fixed numerous issues...

I had the Rset on the 2nd max7219 on pin 17 not 18......fixed that..so the 2nd Matrix is ok now.....I was about to replace the chip too, but I saw that right at the end....


heres my code working in the enclosure... (Attached)

the problem with the LedControl Library is 1.0.1 doesn't support it, even when I exclude SPI...so which IDE version do you have?

The only other thing that is bothering me ..well two things actually...


so the matrices don't scroll across each other, they just all show the same letter as each individual matrix scrolls...

AND The letters are Backwards.....and before you think anything there, I already swapped the wires around thinking it was wired in backwards, but that made it worse.....


bratan


I'm worried your idea will run into problems as you cannot sync the scanning between the MAX7219 chips. I foolishly think the below may be betterwork as your not connecting between driver chips. I only drew one led as I'm meant to me working.

Oh right, diodes! I didn't think of that, thanks! 
This is getting a way too complex for me. I'll never be able to tone transfer something like this :( About ready to give up on the idea....
Xronos Clock - A talking arduino based alarm clock is now available. Check out xronosclock.com for pictures, source code, schematics, and purchasing info :)

Aaron_dyer

oooohh  PCB in Eagle is Tough...we're trying to make a board on a board machine and I hate the traces in the rats nest...


does anyone have an idea about why the scroll letters would be backwards?

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