> This thing could help it go from 12 wires total for both LCD+keys to only 4 using shared I2C wiring, quite nice! Or you could use shift registers which cost

> This thing could help it go from 12 wires total for both LCD+keys to only 4 using shared I2C wiring, quite nice! Or you could use shift registers which cost a few USD cents. On a personal project a long long time ago, I recall using daisy-chained shift registers to control a stupidly high number of relays (think 100+), at an extra BOM cost of around $1. The relay switching time was still much, much larger than the time it took to bit-bang the daisy-chained shift registers for all relays.