I have been working with interfacing the Sparkfun 8x8 2 color matrix with a MAX7221 driver chip. I have noticed an interesting issue and I was wondering if anyone else had experienced it.
When I use the Matrix Library, SEGDP on the 7221 acts as column eight.
When I use LEDControl, SEGDP acts as column one.
This caused me no end of confusion at first as I had wired it up as per the 2xMAX7221 article, and it worked fine using LEDControl based code, but my Matrix based code was always shifted right 1 column and overlapping.
I took a few looks at the Matrix.h code (which I wanted to use due to the easy integration with the Sprite library) but I have yet to figure out where this difference is hardcoded.
Anyway since I need 2 7221s for the 2 colors I will probably either need to use LEDControl anyway or fix the multiple chip part of Matrix library, but I was curious if anyone had an easy explanation of why the two acted differently.