On a different matter now...
Last time we talked about the driving circuit, it looked like this, or at least this is what I understood:
I'm hoping that CrossRoads still reads this topic...
Can somebody please help me clarify the following things:
- What should the value of the resistors between the G and S pins of the NDP6020P-NDs be? I remember CrossRoads mentioning at some point that they could be left out (these resistors). I don't know if that's healthy or not because I don't understand the role of these resistors. Or maybe he meant that the resistors between the anode-driving TPIC6B595 shift register and the G pin of the NDP6020P-NDs is what could be omitted and those 220 Ohm resistors should actually be between the G and S pins of the NDP6020P-NDs?
- If the target current for each LED is 20 mA, have I calculated correctly the valu of the resistors that go to the cathode columns (56 Ohm)?
- Is there anything missing from the diagram?
- Is everything connected as it should be?
I'd really like to be sure that the diagram is 100% correct because this is what I'm going to base my driving circuit on and I reall think I've had enough unpleasant surprises 
Thank you!
Andras