yumology:
I built my own mini LED matrix. One with a common anode and one with common cathode. The common cathode works brilliantly, the common anode, well I can't get it to work at all. Attached is the schematic for what works and doesn't.
So it looks like I can get either a new set of LED matrix's or the 7221's. I can't think of a way to get this to work any other way...
Any luck with your matrix? I have same problem with driving bicolor (common anode) matrix. But someone suggested to use a diodes on SEG A- SEG G lines...