Multiplexing LEDs

[Melonenmonster]

Hello,

this is my initial post here, so first of all I'd like to say thank you to Thorsten Klose for all his great work. Super, Thorsten.

And of course to all you people sharing your knowledge.

I'd like to connect 144 LEDs to a Midibox64E, so I'll use a Variant of the LED-Rings.

Now, due to the multiplexing, the available current of 25mA is divided twice, first because multiple LEDs share a single

kathode-side return path, which is an output of a SR too, second, because the available current is divided in time

between multiple rows sharing a common anode.

Q1: My first question is:  does the cathode-side output really need to be limited to 25 mA? Looking at the diagrams,

it seems to be not the case. And the current I measured with a single LED is indeed around 1/16th of what the

resistor of 220 Ohm would give. So if all LEDs are on, its 11 times the normal 14 mA LED current. So I suspect

the current going into the SR (on an output at around zero volt) can be much more than 25 mA. Is it limited at all?

Q2: Still with a 1/16 sharing, the LEDs are too dark. So I want to use 4 multiplexed rows of 28 LEDs

(only one of 3 LEDs  in a row is on at a time). Is it difficult to modify the software for this purpose?

Could you point me to the places I need to change? I see the LED patterns, but where are the loops and

the link between the MIDI controllers and the SRs? Or is there a place to configure it? I'm a programmer,

so in the end I'll find out, but with a little help I'd feel much better when starting!

Q3: I want these LEDs to be independent  of related encoders, but still need 13 encoders, will they get in

conflict? Where is the place to make a cut? I mean, if the encoders always send relative signals, I need

not to care? They are not linked internally?

Well, these are a lot of questions,  Maybe that's an FAQ,  but I've found nothing, although searched for many hours

(I had many other questions which I could finally resolve.)

Thanks alot!

Ralf