This is probably a stupid question.. .. But if you don't ask and all that ....
Long story short.
Using an Arduino Pro mini, I have built my son a 'Bat Computer' display. Flashing LED's mostly. But even with a shift register, I ran out of inputs. Using the Analogue as input and even RX and TX digital lines.
But after putting it on the wall, I realise it really needs a sound element.
So. My question. As the pro mini is 'full'. Could I use a second pro mini to control an MP3 module. Using a wire soldered to one of the first pro mini led's to initiate a signal so that the second pro min knows when a particular led has been activated?
I can't see a reason why not. But I'd rather ask those who have more experience than I have before I start building this only to find there's some reason it wouldn't work.