A project based on C that uses a Raspberry Pi 4B Rev. 1.2 board to make a stepping motor move counterclockwise or stop entirely depending on the distance calculated from the ultrasonic sensor. For GPIO pin mapping, I used WiringPi (Made by Gordon Henderson under GNU-LGPL) to simplify. Link: http://wiringpi.com/

WiringPi Note: The author has discontinued public releases of WiringPi. The last update was 2.52 for the Raspberry Pi 4B. Although WiringPi is preinstalled on Raspbian systems, the code for installation is as follows:

sudo apt-get install wiringpi

Use:

gpio -v

to check if your version is 2.52.

For more details visit http://wiringpi.com/download-and-install/

To upgrade, visit http://wiringpi.com/wiringpi-updated-to-2-52-for-the-raspberry-pi-4b/

Hardware components used:

• (1) 4 pin Ultrasonic Sensor 5VDC (HC-SR04)
• (1) Step Motor 28BYJ-48 5VDC
• (1) ULN2003 Stepping motorDriver
• (10) Female to Male Jumper Cable
• (1) Male to Male Jumper Cable
• (1) Breadboard powersupply
• (1) Breadboard
• (1) 12V 2.5A AC Adapter (Used for the breadboard power supply)
• Raspberry Pi 4B Rev. 1.2

A 9V battery can also be used with the power supply board if an adapter is obtained.

For the ultrasonic sensor, I used the 5V pin from the Pi to VCC, GPIO 23 for Trig, GPIO 24 for Echo, and the GND pin on the Pi for GND.

I used GPIO 23 for both components since in the code I have that pin as OUTPUT for both components to use.

When compiling the code, run the following commands in terminal at the location of the file:

sudo bash
gcc SteppingMotorWithUltrasonicSensor.c -o SteppingMotorWithUltrasonicSensor -lwiringPi 
./SteppingMotorWithUltrasonicSensor

This project was possible through an electronics kit I purchased from Freenove that provided me with all of the components I used. If interested, it is the "Freenove Ultrasonic Starter Kit for Raspberry Pi" (FNK0024).