Ultrasonic Sensor LED Control Project

Ideas Explored

Initially, I explored multiple ideas, such as using a light-dependent resistor (LDR) for an automatic night light and a temperature sensor for an alert system such as a buzzer going off with the presence of heat. However, I decided to use an ultrasonic sensor to control LEDs because it is a simple yet effective project that demonstrates sensor-based input and real-time response.

Project Explanation

This project uses an ultrasonic sensor to detect objects. The goal is to control two sets of LEDs (red and blue) based on the presence of an object in front of the sensor.

  • When no object is detected → The blue LEDs remain on at all times.
  • When an object (e.g., a hand) is placed in front of the sensor → The blue LEDs turn off, and the red LEDs turn on.

I added a delay after each LED activation so that they would turn on and off in sequence, creating a continuous scattering effect.

I experimented with different delay values and found that setting it to 200 milliseconds produced the best visual effect.

This creates a simple visual indicator of object detection.

Sensors And Components Used and Why

  • Ultrasonic Sensor: Used to detect the presence of an object by measuring the time it takes for sound waves to bounce back.
  • LEDs (Red & Blue): Used as indicators to visually represent whether an object is detected or not.
  • 6 Resistors (220Ω): Used to limit current to the LEDs to prevent damage.
  • A 220Ω resistor is used to limit the current and prevent excessive current flow through the circuit, protecting the LEDs and other components.

The ultrasonic sensor is programmed to detect objects within 15 cm. If an object is detected within this range, the blue LEDs turn off, and the red LEDs turn on.

I used pins 11 and 12 for the ultrasonic sensor—one for the trigger (Trig) and one for the echo (Echo).

The LEDs are connected to pins 2 through 7, with three blue LEDs that remain on by default and three red LEDs that activate when the sensor is triggered.

  • This sensor measures distance using sound waves.
  • It emits a pulse and calculates the time it takes for the echo to return.
  • Used because:
    ✅ It was introduced in class, and I wanted to expand its use.
    ✅ Non-contact detection makes it reliable for multiple applications.
    ✅ Fast response time (ideal for real-time interactions).
    ✅ Can be used in safety and automation systems.

Wiring Diagram

A TinkerCAD wiring diagram has been created to illustrate how to connect the components.

TinkerCAD Wiring Diagram

Pictures/Video/Explanation of Final Project

Video Of Sensor In Action
A fully wired circuit on a breadboard with bright blue LEDs turned on. The wiring is complete, with various jumper wires connected to the microcontroller, ensuring proper functionality.
Circuit Fully Wired Up With Blue LEDs Turned On
  • Summary: The final project successfully detects an object in front of the sensor. The blue LEDs remain on when no object is detected, and when something is placed in front of the sensor, the blue LEDs turn off while the red LEDs turn on.

Challenges Faced

One of the biggest challenges I faced was uploading the code to the microcontroller. I kept receiving an error message (posted below), and it took multiple attempts to resolve. After troubleshooting, I realized the issue was likely due to a faulty USB connection or an incorrect board/port selection in the Arduino IDE. After verifying the correct settings and reconnecting the board, I was finally able to upload the code successfully.

Screenshot of an error message encountered while attempting to upload code to the microcontroller. The error message indicates a failed connection or incorrect port selection, requiring multiple attempts to resolve.
Error Message When Trying To Upload Code To Microcontroller

Lessons Learned

  • The importance of proper wiring and ensuring correct power connections (5V and GND).
  • How to use the sensor and read values to control outputs in real-time.
  • Debugging Arduino code and troubleshooting hardware issues.

I learned how to efficiently wire a breadboard and the importance of proper power distribution. One of my initial mistakes was forgetting to connect the 5V power line to the positive rail and ground (GND) to the negative rail on the breadboard. Without these connections, the Arduino wasn’t receiving enough power to function properly. I also realized that even a single misconnected wire can cause the entire circuit to fail, emphasizing the need for careful wiring and double-checking connections.

Relevant Data Used

  • Ultrasonic Sensor Code from Canvas
  • Canvas Slideshow
  • Resistor Color Code Chart – Used to ensure I selected the correct resistor values for my circuit.

Citations

EEPROM. Resistor color code. Available at: https://eepower.com/resistor-guide/resistor-standards-and-codes/resistor-color-code/ (Accessed: 10 March 2025).

Krevolin, J. Ultrasonic_Sensor_LED_BME66.ino. (n.d.).

Potential Uses for Microcontrollers in My Life (Extra Credit)

Microcontrollers have many applications in everyday life. Some potential uses include:

  • Smart home automation – controlling lights or appliances based on movement and motion sensors)
  • Security systems – Using sensors to detect movement and trigger an alarm or send alerts.
  • Medical devices – Developing a wearable heart rate monitor using sensors and a microcontroller.
  • DIY electronics projects – Using moisture sensors to control water flow for houseplants.
  • Assistive technology – motion or ultrasonic based navigation aids for visually impaired individuals)

This project was a great introduction to sensor-based automation, and I look forward to building more advanced projects in the future!