I'll certainly play with the SR modes as well.
Noted on the number of pins required for multiple LCD's via SR.
Could you not cascade by connecting Q7S of one into DS of the next, with Latch and Clock shared. If you kept track of whih LCD was to be updated the could you not shift in the required number of bits, with unchanged LCD(s) having the SR bit set to state that would cause no change?
Would that not effectively allow you to daisy chain more and more displays for no extra pins? It might have a speed effect if you had many many displays, but how many would seriously affect update speed by causing so many bits to be shifted in?
I'm not conversant with the low level driving of the LCD's, but it just occurs to me that you might control LCD3, for example, by only changing bits 8-15. With bits 0-7 and 16-31 in a 'neutral' state then LCD's 1, 2 & 3 wouldn't be driven by their SR.
When we you want to drive one display you have to do a full write across all SR but the bits for the others are just set to cause no change?