I want to use many (about 30) switches as inputs to my Arduino Uno. I've built a circuit using four 74LS30 (nine input NOR gates) to multiplex 15 switches down to 4 pins (16th state is when all switches are off, 0000) which works. However, expanding this to accept inputs from more switches will mean that the circuitry will get VERY complicated. :( It's not just a matter of adding another 74LS30, as [u]all[/u] the inputs on the current ones are in use. I'm limited in the number of available pins on the Arduino that I can use, as I'm also using a MotorSheild to control a DC motor and some servos.
Basically, what I need is a 32 line to 5 line (binary) multiplexer. Is there an IC (or two) that will do this for me?