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How to Control LED Intensity Using Node-RED
2023-06-12 | By Don Wilcher
Traditional approaches like potentiometers or solid-state dimming circuits have often been used to control an LED’s intensity. Although those approaches work great for controlling an LED’s intensity locally, a wireless method provides greater remote control. In this article, you’ll learn how to use Node-RED to control the intensity of an LED.
If you are new to using Node-RED, here are a few articles to learn how to use the flow programming language. Make sure to check them out so you can get the most out of this article!
How to Install and Get Started with Node-RED
Create User Dashboards for IoT Projects using Node-RED
The Concept: Using Node-RED for LED Intensity
Node-RED provides a variety of IoT possibilities for home automation, smart sensor monitoring, and wireless embedded control applications. The idea behind using Node-RED to operate an LED is to be able to control its intensity wirelessly from a mobile device like a smartphone or tablet. Connecting a Node-RED dashboard using your home Wi-Fi network allows the LED’s intensity to be easily adjusted; a slider allows the LED’s intensity to be changed by sliding the widget with your finger. This Node-RED LED dimmer controller requires only a few off-the-shelf components.
Node-RED LED Dimmer control concept drawing.
The Bill Of Materials
Building the Node-RED Dimmer controller requires three major components: a Raspberry Pi, a 220Ω resistor, and a red LED. To obtain the best operating results with Node-RED, a Raspberry Pi 3 or later should be used for this project.
You can find the bill of materials (BOM) and schematic for this here. A solderless breadboard and jumper wires will be needed to wire the 220Ω resistor and the red LED to the Raspberry Pi General Purpose Input Output (GPIO) pin 19.
Wiring the LED Circuit
Wiring the LED circuit to the Raspberry Pi is quite easy to do -you will place the red LED and the 220Ω resistor on a solderless breadboard. The proper orientation of the red LED on a solderless breadboard is important: if the LED’s orientation is incorrect, the circuit will not work. The resistor’s orientation is not critical; therefore, the placement of the component is not a major concern.
The solderless breadboard electrical wiring diagram.
The Pi T Cobbler Plus extension board provides convenience for wiring the LED circuit to the Raspberry Pi GPIO19 pin. If a Pi T Cobbler extension board is not available, you will need to make the wire connections directly to the Raspberry Pi’s 40-pin connector.
The completed Raspberry Pi – LED circuit on a solderless breadboard.
With the wiring completed, the Node-RED flow control nodes can be built.
Building the Node-RED Flow Control Nodes
Building the LED Intensity Controller requires three widget components: a slider node, a GPIO out node, and a gauge node. The slider node will connect the GPIO and the gauge nodes. Messages will be sent to the gauge and GPIO nodes to display the LED intensity level and provide a dimming control signal; the dimming control is a pulse-width modulated (PWM) signal to adjust the current flowing through the red LED.
LED dimming flow control diagram.
The configuration (properties) of each node can be seen below.
Slider node Configuration.
The GPIO out node properties are configured as shown next.
GPIO out node configuration.
Finally, the configuration of the gauge widget properties is illustrated below.
Gauge node configuration.
Testing the Wi-Fi LED Intensity Controller
With the flow control diagram nodes configured, you may enable the project by pressing the Deploy button on the Node-RED editor. Once deployed, the dimming control dashboard and the interactive widgets will be visible and ready to operate the LED intensity. The Node-RED gauge will show the LED intensity level based on the slider widget’s adjusted position.
Deployed and operational LED Dimming Control Dashboard
The dashboard can be viewed on a desktop personal computer (PC), smartphone, or tablet. I used an Amazon Fire tablet to test out the Wi-Fi based controller. You can see the actual dashboard controller in operation by clicking here for the video clip.
Tablet setup to test the Node-RED Wi-Fi LED Dimmer (Intensity) Controller.
Summary
In this article, we saw how to wire an LED circuit to a Raspberry Pi’s GPIO pin and how to select dashboard widgets and wire them to create an interactive Wi-Fi controller. Finally, we looked at editing the properties of the dashboard widgets and how to deploy the flow control diagram and test the operation of the intensity on an LED. Let us know how your project has come together and what you would like us to work on next in the Node-RED ecosystem!
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