GoForSmoke:
SPI is Serial Peripheral Interface but when you look it up, SPI will do. It's fast and only selected devices read from or write to the bus.Beyond that, I could spend hours typing what's already out there.
Gammon Forum : Electronics : Microprocessors : SPI - Serial Peripheral Interface - for Arduino
TomGeorge:
Hi,
You are talking about fingers, knuckles and stacks.
What is the application?Tom...
Application is a mechanical hand 
should be able to complete basic motor tasks.
Sorry for the delay in reply, busy weeks and all that. Would this be simpler if I used a wifi/BT header on the stacks and could link them all to the Arduino IDE or a from scratch control program? I'd imagine it would and could save some time and effort too, would pay off to not have to be wired direct to the hand too.
Thanks