Step by step...

I'm quite advanced now with the soldering of the boards. However I'd like to test the multiplexing of them.

First I start to think how mount everything on the screen back :

It fits very sharp on the diagonal.

I decided to switch to a smaller micro controller, one of the PIC I already have and used for the LCD big_clock. With it I can easily scan the boards and pins plus enable serial interface. It have plenty enough of RAM as well.

Then I cabled 2 boards for 16x16 pixels drive :

And well, it start to be more and more likely this strategy could work !

Next step: more cabling ;)