MAX7221 PCB

Okay, I've been working on this for a while and I want some feedback. This is a board for the Sparkfun RGB backpack with three MAX7221CWGs. I made it in DipTrace and it's double-layered if the silkscreen is left out when it's printed, it should work for toner transfers.

U1 is the matrix and U2 is the SPI connection. The 4 stray vias are for alignment.

Schematic: http://www.mediafire.com/?d1oxm29n4x3

hammertime,

It would be easier to understand what you’re trying to do if you posted the schematic.
(I was lost in a world of vias!)

I’m confused anyway though. Isn’t the Sparkfun backpack supposed to eliminate the need for driver chips?

Those are pretty big caps too! (C3 & C4). They remind me of those wax paper jobs that I used to melt when I was a kid.
:slight_smile:

That link is for the schematic and I meant the matrix itself. Oh, and I am unsure about the size of the caps, but I placed them where they are to make them easy to change jic.

Sorry, I don't have the application to read that schematic. Perhaps, others will or you can post an image.

It's freeware download it at http://www.diptrace.com/downloads/dipfree_en.exe if you want.

double-layered if the silkscreen is left out when it’s printed, it should work for toner transfers

With the number of vias in the layout, etching this at home would be, if not impossible, very involved with lots of precision drilling and lots of tiny wire links to fill the vias.

All I get is the PCB layout from the links above and not the schematics. :'(

Do I assume thought from the use of the drivers that this design will only produce 7 colours. That is you will not be able to mix various proportions of colours?