Actually guys, I am using Nodemcu for my project. As that board only provides 11 GPIO pins (which can be actually used) so I have a question regarding a thing.
As I will be using ESP8266 motor shield and in that shield D1 - D4 pins are dedicated to the 04 DC motors which have to be used. So I can use only 7 pins which are D0, D5 - D8, 2 SD (SD2 and SD3) pins. Also after including couple of sensors I will be left only with 2 GPIO pins.
In those 2 pins I want to use 74HC4051 multiplexer. The pin-layout of this mux is as follows:
As one can see, there are 03 Select lines for the Input. So that is why I will be able to get 2^3 = 8 Output lines from the mux.
I only want to get 4 output lines from the mux which can be achieved through 2 Select lines. So can I Gnd the S2. Will it harm the IC? If yes, then how can I use this IC to use only 2 select lines?
Any help will be of great help