In this post, you’ll learn how to use a shift register (IC 74HC595) and a 7-segment display (model 5161AS) to track people entering and leaving a room. With these components and a few buttons, you’ll build a system that displays the current number of people in the room. Previously, I covered using the 7-segment display and shift register separately; now, I’ll show you how to combine them and add some cool effects to the display.

This project, although simple, contains several elements essential for working with Arduino and in general with microcontrollers. In addition to working with the RGB diode, the project involves using the analogWrite function to work with (certain) digital pins. Using this function implies the use of PWM signals, and also includes usage of user functions.