It is always wise to take a step back and think through your design carefully before rushing to build anything. Part of good engineering practice involves developing a clear design plan first.
For this project, you must first determine the main purpose of your smart LED lighting system. Are you aiming to create motion-activated lights that automatically switch on when someone walks into a room?
Or are you thinking of making a “sunset” night light that slowly dims and changes colour to signal bedtime? Perhaps you want a warning light that switches from green to red as people get closer to your room, or maybe a music-responsive party lighting system? The options are endless, and the choice is entirely yours.
LED Mood Lamp with Arduino Uno R3 (Photo: LED Mood Lamp/Shutterstock)
Regardless of the project you choose, you must carefully plan the type of sensors you will need, the exact spots where you will install your LED strips, and the way the lights will respond to sensor input.
It is important to stick to the engineering design process guide, and once you are satisfied with your planning, you can proceed to the next phase, which is prototyping.
Using Your LED Strip
When putting together a more involved system, it is advisable to build and check each section one by one rather than attempting to assemble everything at once. Doing so allows you to confirm that every component is functioning correctly before testing the entire setup.
It also becomes much easier to detect and fix any problem when something goes wrong. For this smart lighting project, it is best to connect and test your LED strip on its own before introducing any sensors.
Should you need to, trim your LED strip to the desired length. Many LED strips come with pre-marked lines where you can safely cut, usually after every third LED. Always consult the manufacturer’s instructions before cutting.
If required, solder wires onto the LED strip’s tabs and cover the connections with heat shrink tubing, as shown below. It is helpful to use different coloured wires so you can easily identify each one. If your LED strip already has wires attached, you can skip soldering.
An image shows four wires neatly soldered to an LED strip, with heat shrink tubing applied for protection. The figure below illustrates a breadboard layout for connecting an analog RGB LED strip to an Arduino.
Download the led_strip_fade.ino example code and upload it to your Arduino board. This code employs the analogWrite function, allowing you to adjust the brightness of each LED colour from 0 (completely off) to 255 (full brightness).
Switch the breadboard’s power button to the “on” (up) position. You should immediately notice your LED strip fading smoothly through different colours. If nothing lights up or the colours do not change, revisit your breadboard connections, paying special attention to the MOSFET connections.
Next, open the Serial Monitor in the Arduino IDE (under Tools → Serial Monitor) and observe the red, green, and blue values as they fluctuate. Try to link these values with the changing colours on your LED strip.
Experiment by adjusting the fadeDelay variable in the code and observe what effect it has.
Notice that at least one colour value (red, green, or blue) remains zero in the provided code.
See what happens if you turn on all three colours at the same time.
Optional: Observe how the brightness level of the LEDs relates to the analogWrite values. For instance, if you set a single colour’s brightness to 128 and leave it steady, does it seem half as bright compared to setting it at 255?
Using a Sensor
Once you confirm that your LED strip is working perfectly, the next step is to test your sensor separately. Testing each component independently helps you to easily pinpoint any issues with your wiring or setup.
The wiring diagram an LED strip working perfectly (Photo: Wiring diagram/Alamy)
Save your LED testing code and open a new blank file.
Following the wiring diagram shown above, you should have enough space on the left side of your breadboard to attach one or more sensors.
Connect your chosen sensor to the Arduino and create a simple program to test its output. You could control a small LED based on sensor input or simply print sensor readings to the Serial Monitor.
Make sure you follow the relevant tutorials to test your specific sensor. Video tutorials are available for the five sensor types displayed in diagram (PIR sensor, ultrasonic sensor, potentiometer, microphone, and photoresistor).
If your sensor type is not among these, you can visit the “How to Use an Arduino” guide or search for a tutorial online that matches your sensor.
Reflect on how your sensor will fit into your project and think carefully about its positioning. For example, if you start testing an ultrasonic sensor by waving your hand in front of it while it is lying flat on a table, that might be fine for basic tests. But if you want the sensor to detect someone entering a room, it might be better to mount it on a wall.
Also, based on how far your Arduino is located from your sensor, you might need longer wires to make proper connections. Always test your sensor in the real-world conditions you expect for the final setup.
Making Your LED Strip React to a Sensor
Up to this point, you have written one code controlling the LEDs and another code to read your sensor’s data. Your next task is to merge both functions and make the LEDs respond according to the sensor readings. If you need assistance getting started, there are sample programs available for the five sensors discussed.
Take note that the Arduino map function can be very handy. It helps to convert the sensor’s output values, which can vary greatly, into a suitable range for LED brightness control (0 to 255).
You have the freedom to tweak and modify these sample programs as you wish. If you intend to use multiple sensors, you can combine the different codes. If your project involves an entirely different sensor, you are free to write your own program from scratch.
Remember, there is no single correct way to complete this project; your design should meet the specific goals you set earlier during your planning stage.
After writing and uploading your program, conduct thorough tests. You might find yourself adjusting threshold values for sensors or tweaking the red, green, and blue settings to achieve your preferred colours.
Once everything works perfectly, you can proudly show off your personalised smart RGB LED lighting project to your friends and family!
