Controlling RGB LED Using Arduino

In this tutorial I will be demonstrating how to control RGB LED using the arduino uno microcontroller board. I will be explaining step-by-step on how this beginner level project works using equations, a circuit diagram, and an oscilloscope.

Components used:

1. Arduino uno

2. RGB LED

3. 220-ohm resistor x3

4. Connecting wires

5. Breadboard

6. Oscilloscope (optional)

In order to fully understand how this project works I must first explain how an LED functions and elaborate the importance of a duty cycle.

An LED like any other electronic component has a forward voltage value and current value. In other words, in order to successfully turn on a Red LED you need to supply the component with a minimum voltage of 1.63V and minimum current of 2mA. The same rule applies for the green LED and blue LED but the forward voltage and current LED is different. Please refer to the table below that clearly displays forward voltage and LED current for the red, green and Blue LED.

Red LED

Forward voltage (Vf): 1.63-2.0V

LED current (Iled): 1.6-2.0mA

Green LED

Forward voltage (Vf): 1.9-4.0V

LED current (Iled): 1.9-4.0mA

Blue LED

Forward voltage (Vf): 2.48-3.7V

LED current (Iled): 2.5-3.7mA

Next, we will be calculating the current limiting resistor for each LED pin. By default, you can choose 220-ohm resistor for each LED pin and the circuit will function normal but if your goal is to build a project with accuracy and precision, it is recommended to use equations, a multimeter and an oscilloscope to build the circuit. For the purpose of this beginner level tutorial, I’ve used the default 220 ohm to make things easier for you, but I recommend building the circuit according to specifications and I’ll show you how. The equation used to calculate each resistor for LED pins goes as follows:

R=(Vs-Vf) / Iled

Vs = Supply voltage which is 5V

Vf and Iled values can be found above.

R is the current limiting resistor value for LED pin measured in ohms.

So, for this tutorial I have used pulse width modulation (PWM) which is located in the Arduino uno board in order to create a variety of colours using RGB LED. The program which is uploaded to Arduino uno will be responsible for manipulating the RGB LED duty cycle.

A duty cycle is extremely useful especially to those who want to see the behaviour of a circuit in waveforms and to understand how it functions. In order to see and understand the RGB LED project, I have used an oscilloscope called Yeapook ADS1013D Handheld digital oscilloscope. This oscilloscope is extremely useful and convenient because it is small, cheap and works efficiently.

Yeapook ADS1013D Handheld digital oscilloscope:

Youtube video link: https://youtu.be/eaHDQwVToX8