Search the Community

Story A NeoPixel ring controlled by a DHT11 sensor and an Arduino Nano can be a fascinating project that combines temperature sensing with visual feedback. This article will guide you through the process of building such a system. Materials Needed Arduino Nano DHT11 Temperature and Humidity Sensor Neo Pixel Ring Jumper Wires Get PCBs For Your Projects Manufactured You must check out PCBWAY for ordering PCBs online for cheap! You get 10 good-quality PCBs manufactured and shipped to your doorstep for cheap. You will also get a discount on shipping on your first order. Upload your Gerber files onto PCBWAY to get them manufactured with good quality and quick turnaround time. PCBWay now could provide a complete product solution, from design to enclosure production. Check out their online Gerber viewer function. With reward points, you can get free stuff from their gift shop. Also, check out this useful blog on PCBWay Plugin for KiCad from here. Using this plugin, you can directly order PCBs in just one click after completing your design in KiCad. Step 1: Connecting the Hardware First, connect the DHT11 sensor and the Neo Pixel ring to the Arduino Nano. The DHT11 sensor can be connected to any digital pin on the Arduino Nano. The Neo Pixel ring should be connected to the D2 pin of the Arduino Nano. Step 2: Installing the Libraries You will need to install the DHT library and the Adafruit Neo Pixel library in your Arduino IDE. These libraries contain the necessary functions to interact with the DHT11 sensor and the Neo Pixel ring. First Navigate to Sketch > Include Library > Manage Libraries... In the Library Manager, there is a search box. Type “DHT sensor library” into the search box. In the search results, find the library named “DHT sensor library” by Adafruit. Click on it, then click the “Install” button. And that’s it! You’ve successfully installed the DHT11 sensor library in Arduino IDE. This library should now be available for inclusion in your sketches. Step 3: Programming the Arduino The next step is to program the Arduino Nano. The program should read the temperature from the DHT11 sensor and change the color of the Neo Pixel ring based on the temperature. For example, you could program the Neo Pixel ring to display a blue color when the temperature is below a certain threshold. A green color when the temperature is within a comfortable range, and a red color when the temperature is above a certain threshold. Step 4: Testing the System After programming the Arduino Nano, it’s time to test the system. Power up the Arduino and observe the color of the Neo Pixel ring. Try changing the temperature around the DHT11 sensor (for example, by blowing hot or cold air onto the sensor) and see if the color of the Neo Pixel ring changes accordingly. #include <Adafruit_NeoPixel.h> #include <Adafruit_Sensor.h> #include <DHT.h> #include <DHT_U.h> #define DHTTYPE DHT11 // DHT 11 #define DHTPIN 3 DHT_Unified dht(DHTPIN, DHTTYPE); #define PIN 2 // Neo Adafruit_NeoPixel strip = Adafruit_NeoPixel(8, PIN, NEO_GRB + NEO_KHZ800); void setup() { Serial.begin(115200); dht.begin(); sensor_t sensor; strip.begin(); strip.setBrightness(100); strip.show(); } void loop() { sensors_event_t event; dht.temperature().getEvent(&event); Serial.print(F("Temperature: ")); float temp1 = event.temperature; Serial.print(temp1); Serial.println(F("°C")); dht.humidity().getEvent(&event); Serial.print(F("Humidity: ")); float hum1 = event.relative_humidity; Serial.print(hum1); Serial.println(F("%")); if (temp1 >= 28 && temp1 < 31) { strip.clear(); // Set all pixel colors to 'off' for (int i = 0; i < 12; i++) { // For each pixel... strip.setPixelColor(i, strip.Color(0, 150, 0)); strip.show(); } } else if (temp1 < 28) { strip.clear(); for (int i = 0; i < 12; i++) { // For each pixel... strip.setPixelColor(i, strip.Color(0, 0, 150)); strip.show(); } } else { strip.clear(); for (int i = 0; i < 12; i++) { // For each pixel... strip.setPixelColor(i, strip.Color(150, 0, 0)); strip.show(); } } } Conclusion Building a DHT11-controlled Neo Pixel ring with an Arduino Nano is a fun and educational project combining temperature sensing and visual feedback. With this system, you can visually monitor the temperature in a room and get a sense of whether the temperature is within a comfortable range.

Things used in this project Hardware components Raspberry Pi 4 Model B × 1 Adafruit NeoPixel Ring: WS2812 5050 RGB LED × 1 Software apps and online services Node-RED How to Control NeoPixel LEDs with Node-RED and Raspberry Pi NeoPixel LEDs are a popular type of addressable RGB LEDs that can create amazing effects and animations. They are easy to control with a microcontroller like Arduino, but what if you want to use them with a Raspberry Pi? In this article, we’ll show you how to use Node-RED, a graphical programming tool, to control NeoPixel LEDs with a Raspberry Pi. Get PCBs For Your Projects Manufactured You must check out PCBWAY for ordering PCBs online for cheap! You get 10 good-quality PCBs manufactured and shipped to your doorstep for cheap. You will also get a discount on shipping on your first order. Upload your Gerber files onto PCBWAY to get them manufactured with good quality and quick turnaround time. PCBWay now could provide a complete product solution, from design to enclosure production. Check out their online Gerber viewer function. With reward points, you can get free stuff from their gift shop. What You’ll Need To follow this tutorial, you’ll need the following components: A Raspberry Pi board with Raspbian OS installed A WS2812B NeoPixel LED strip Some jumper wires You’ll also need to install Node-RED and the node-red-node-pi-neopixel node on your Raspberry Pi. We’ll explain how to do that later. Wiring the NeoPixel LED Strip The NeoPixel LED strip has three wires: 5V, GND, and DATA. The 5V and GND wires provide power to the LEDs, while the DATA wire carries the signal that controls the color and brightness of each LED. The Raspberry Pi can provide 5V and GND from its GPIO pins and connect the DATA pin to GPIO 18. The reason we use GPIO 18 is because it supports PWM (pulse-width modulation), which is needed by the node-red-node-pi-neopixel node. You can use other PWM-enabled GPIO pins, but you’ll need to change the settings accordingly. Installing Node-RED and node-red-node-pi-neopixel Node-RED is a graphical programming tool that lets you create applications by connecting nodes that perform different functions. You can install Node-RED on your Raspberry Pi by following this guide. To control the NeoPixel LEDs with Node-RED, you need to install a special node called node-red-node-pi-neopixel. This node can drive a strip of NeoPixel or WS2812 LEDs from a Raspberry Pi. You can install it by running the following command. npm install node-red-node-pi-neopixel You also need to install the Neopixel python driver, which is used by the node-red-node-pi-neopixel node. The easiest way to do that is to use the Unicorn HAT drivers install script, which you can run with this command: After installing node-red-node-pi-neopixel, you need to restart Node-RED for the changes to take effect. Creating a Node-RED Flow Now that everything is set up, you can create a Node-RED flow to control the NeoPixel LEDs. A flow is a collection of nodes that are connected by wires. Each node has an input and an output and can perform some action or function. To create a flow, you need to open the Node-RED editor in your web browser. By default, it runs on port 1880 of your Raspberry Pi’s IP address. For example, if your Raspberry Pi’s IP address is 192.168.1.3, you can access the Node-RED editor at http://192.168.1.3:1880. In the editor, you’ll see a palette of nodes on the left side, a workspace in the middle, and an info panel on the right side. You can drag nodes from the palette to the workspace and connect them by dragging wires from one node’s output to another node’s input. Here’s an example of a neo-pixel flow that controls the LEDs based on our user inputs. To create this flow, you need to do the following steps: Drag Copy and import the below JSON node-red flow. Change the LED count JSON Files: [ { "id": "60627e22237dc214", "type": "tab", "label": "Flow 2", "disabled": false, "info": "", "env": [] }, { "id": "f0395033145e84d7", "type": "ui_colour_picker", "z": "60627e22237dc214", "name": "Color Picker", "label": "COLOR PICKER", "group": "cd687a95.00e108", "format": "rgb", "outformat": "string", "showSwatch": true, "showPicker": true, "showValue": true, "showHue": false, "showAlpha": false, "showLightness": true, "square": "false", "order": 1, "width": 0, "height": 0, "passthru": true, "topic": "", "topicType": "str", "x": 490, "y": 380, "wires": [ [ "f6f366218f267026" ] ] }, { "id": "f6f366218f267026", "type": "function", "z": "60627e22237dc214", "name": "Set Color", "func": "var count = global.get('count')||0;\nmsg.payload = msg.payload.replace(/[rgb()\\s]/g,\"\");\nif(count===0){\n msg.payload = msg.payload;\n}\nelse{\n msg.payload = (count-1) + \",\" + msg.payload;\n}\n\nreturn msg;", "outputs": 1, "noerr": 0, "x": 680, "y": 380, "wires": [ [ "b4a4a424433ab3a2" ] ] }, { "id": "cc6b4172d7245dfd", "type": "function", "z": "60627e22237dc214", "name": "Rainbow Effect", "func": "var numberOfLEDs = 8;\nvar i;\nvar j;\n\nif (msg.payload==1)\n{\n for (i = 0; i < 255; i++) {\n\n for (j = 0; j < numberOfLEDs; j++) {\n\n var pos = 0;\n pos = Math.round(((j * 255 / numberOfLEDs) + i)) & 255;\n\n if (pos < 85) {\n var red = pos * 3;\n var green = 255 - pos * 3;\n var blue = 0;\n }\n else if (pos < 170) {\n pos -= 85;\n var red = 255 - pos * 3;\n var green = 0;\n var blue = pos * 3;\n }\n else {\n pos -= 170;\n var red = 0;\n var green = pos * 3;\n var blue = 255 - pos * 3;\n }\n var setColor = j + ',' + red + ',' + green + ',' + blue;\n node.send({ payload: setColor });\n }\n }\n}\nelse { \n msg.payload = \"0,0,0\"\n}\n\nreturn msg;\n\n\n", "outputs": 1, "timeout": "", "noerr": 0, "initialize": "", "finalize": "", "libs": [], "x": 700, "y": 440, "wires": [ [ "b4a4a424433ab3a2" ] ] }, { "id": "b4a4a424433ab3a2", "type": "rpi-neopixels", "z": "60627e22237dc214", "name": "Neo Pixel", "gpio": "18", "pixels": "8", "bgnd": "", "fgnd": "", "wipe": "60", "mode": "pixels", "rgb": "rgb", "brightness": "100", "gamma": true, "x": 900, "y": 420, "wires": [] }, { "id": "125d1e66ad34b180", "type": "ui_switch", "z": "60627e22237dc214", "name": "", "label": "Rainbow switch", "tooltip": "", "group": "cd687a95.00e108", "order": 3, "width": 0, "height": 0, "passthru": true, "decouple": "false", "topic": "topic", "topicType": "msg", "style": "", "onvalue": "true", "onvalueType": "bool", "onicon": "", "oncolor": "", "offvalue": "false", "offvalueType": "bool", "officon": "", "offcolor": "", "animate": false, "x": 500, "y": 440, "wires": [ [ "cc6b4172d7245dfd" ] ] }, { "id": "cd687a95.00e108", "type": "ui_group", "name": "Neo Pixel Controller", "tab": "aa146f4d.b53ca", "order": 1, "disp": true, "width": "6", "collapse": false }, { "id": "aa146f4d.b53ca", "type": "ui_tab", "name": "Demo Lab", "icon": "dashboard", "order": 1, "disabled": false, "hidden": false } ] Neo Pixel Node Setup: Select the PIN and change the LED count as per your neo-pixel configuration. Deployment Setup: Next hit the deployment button and navigate to the UI page of the Node-red with /ui in the node-red page URL. You can select the LED color via the neo-pixel circle. Also, if you toggle the rainbow switch it will apply the rainbow effect to the ring. Conclusion In this article, I have shown you how to control NeoPixel LEDs with Node-RED and Raspberry Pi.