dougp:
That got me thinking. You could run SCK to say, the enable of a (74LS138) 1-of-8 decoder and use two Arduino pins to drive the address select of the decoder. The decoder would give you the fanout and you could clock each bank of SRs independently and still utilize SPI.Possible?
Maybe, but over-complicated and needs two more Arduino pins. Just buffer the CLK line enough for 30 chips.