How to Use Ultrasonic Sensors in Arduino Project

Building the Code

1. 
   Download Arduino IDE and other related libraries. You would need to download the Arduino coding program as well as some needed libraries.

   1. Head to the official Arduino website. You will find a tab at the top named Software which would have a Download option. This would lead you to the download page where you will be able to download Arduino IDE for Mac, Windows, and Linux.
   2. Find a good library for your Arduino project. Search for any ultrasonic sensor library online and look at the example to understand how to use it. Repositories like GitHub have lots of open-source Arduino projects that you can use.
2. 
   Make a new file and folder. This is done to have a designated area to find your code but the Arduino file also requires the file to be in a folder with the same name. Otherwise, an error would pop up.

   1. Make a new folder in your computer for your project and then open the Arduino program.
   2. Once the Arduino program is opened, save a new file to the recently made folder with a proper name. You might notice the Arduino file is automatically saved in a new folder with the same name.
3. 
   Add necessary libraries. This is a necessary step needed to run the code.

   1. Go to "Sketch" > "Include Library" > "Add .zip Library" and select the libraries needed, for this example it will be "HC - SR04".
4. Adjust the settings. On the Arduino program, you would need to adjust some setting so it can communicate with the board.

   1. You would need to select what type of board you are using. There are different types of Arduino microcontrollers; however, this example will use an Arduino/Genuino uno. Do this by going to the top and selecting "Tools" > "Boards" and selecting.
   2. You would also need to choose what Port to use. In "Tools" > "Port," choose COM3 or COM4.
5. 
   Define libraries and variables. This gets the libraries that will be used for the code but also lets you make variables that you will use and change later throughout the code. Variable names could be different.

   1. #include "SR04.h" lets you use the SR04.h library needed to activate and use the ultrasonic sensor.
   2. All definitions that start with #define just lets you assign names to pin numbers of the Arduino. For example, #define RED 6 defines pin 6 to the RED variable.
   3. You also made variables to store the different values of the different colors which will be integers.
6. 
   Write the setup. this is to tell the board its initial tasks before the repeating loop is run. In the previous step, you assigned names to pin of the board. Now you will assign what the pins will do.

   1. The function pinMode(RED, OUTPUT) gets the first variable, RED and assigns what the pin will do, here RED pin number 6 will be an output.
   2. The function digitalWrite(RED, LOW) gets the first variable, RED pin 6 and sets a low voltage.
7. 
   Add the loop. This is the part of the code that would be looped over and over. This is probably also the hardest part of the programming process while initially writing it and figuring the best approach.

   1. First you take the distance reading and set the initial voltage of the colors to zero.
   2. An if statement then checks to see if the distance is between 0 -127.5 or 127.5 - 255. Both if functions then use a formula to determine how strong the brightness of each color should be. Here you made it so the RGB LED is red when a surface or object is close but turns green and then blue the further it gets.