AVR based parking system - Simple Arduino Based Automated Parking Lot System - page 10

read_mux() function
This function receives the state of each parking slot and stores them in car[1] to
car[16] variables. We use a 16×1 multiplexer between 16 signals from parking slots and
one pin of microcontroller. So for example, when the microcontroller want to update
car[16] variable, it sets the four control inputs of multiplexer( mux1 to mux4 ). Accord-
ingly, the multiplexer send its 16 th input to its output and then microcontroller reads the
multiplexer output and stores it in car[16] variable.
mux1=1; mux2=1; mux3=1; mux4=1;
car[16]=!mux_out;