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Introduction In this tutorial, you will learn how to use Node-RED, a visual programming tool for the Internet of Things (IoT), to control an LED on an ESP32 board with a Raspberry Pi as the MQTT broker. MQTT is a lightweight and simple messaging protocol that allows devices to communicate with each other over a network. You will need the following components for this project: ESP32 development board USB cable to connect the ESP32 to your computer Raspberry Pi with Node-RED Computer with Arduino IDE and PubSubClient library installed 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. Step 1: Create a Device on Qubitro The first step is to create a device on the Qubitro platform. A device represents your physical device (Raspberry Pi) on the cloud. You need to create a device to obtain the MQTT credentials and topics for your Raspberry Pi. To create a device on Qubitro, follow these steps: 1. Log in to your Qubitro account and create a new project 2. Then go to the Devices page, select MQTT as the communication protocol, and click Next. 3. Enter all the details. 4. Copy the Device ID, Device Token, Hostname, Port, Publish Topic, and Subscribe Topic. You will need these values later in the code. Click Finish. You have successfully created a device on Qubitro. You can see your device on the Devices page. Step 2: Flash ESP32 with Arduino IDE The ESP32 is a powerful and versatile microcontroller that can run Arduino code. You will use the Arduino IDE to program the ESP32 and make it communicate with the MQTT broker using the PubSubClient library. To install the ESP32 board in Arduino IDE, you can follow the instructions in this tutorial or use the steps below: Open the preferences window from the Arduino IDE: File > Preferences. Go to the “Additional Board Manager URLs” field and enter the following URL: https://dl.espressif.com/dl/package_esp32_index.json. Open Boards Manager (Tools > Board > Boards Manager), search for ESP32, and click the install button for the “ESP32 by Espressif Systems”. Select your ESP32 board from Tools > Board menu after installation. Open the library manager from Sketch > Include Library > Manage Libraries. Search for PubSubClient and click the install button for the “PubSubClient by Nick O’Leary”. Restart your Arduino IDE after installation. Step 3: Connect LED to ESP32 The LED is a simple device that emits light when current flows through it. You will connect the LED to one of the GPIO pins of the ESP32 and control its state (on or off) with MQTT messages. In my case I'm going to use the onboard LED in the ESP32 Dev board. Step 4: Write Code for ESP32 The code for the ESP32 will do the following tasks: Connect to your Wi-Fi network Connect to the Qubitro MQTT broker on Raspberry Pi Receive messages from “output” and turn on or off the LED accordingly You can copy and paste the code below into your Arduino IDE. Make sure to replace <your_ssid>, <your_password>, <your_Qubtro_Credientials> with your own values. #include <WiFi.h> #define DEBUG_SW 1 #include <PubSubClient.h> //Relays for switching appliances #define Relay1 2 int switch_ON_Flag1_previous_I = 0; // Update these with values suitable for your network. const char* ssid = "ELDRADO"; const char* password = "amazon123"; const char* mqtt_server = "broker.qubitro.com"; // Local IP address of Raspberry Pi const char* username = ""; const char* pass = ""; // Subscribed Topics #define sub1 "output" WiFiClient espClient; PubSubClient client(espClient); unsigned long lastMsg = 0; #define MSG_BUFFER_SIZE (50) char msg[MSG_BUFFER_SIZE]; int value = 0; // Connecting to WiFi Router void setup_wifi() { delay(10); // We start by connecting to a WiFi network Serial.println(); Serial.print("Connecting to "); Serial.println(ssid); WiFi.mode(WIFI_STA); WiFi.begin(ssid, password); while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); } randomSeed(micros()); Serial.println(""); Serial.println("WiFi connected"); Serial.println("IP address: "); Serial.println(WiFi.localIP()); } void callback(char* topic, byte* payload, unsigned int length) { Serial.print("Message arrived ["); Serial.print(topic); Serial.print("] "); if (strstr(topic, sub1)) { for (int i = 0; i < length; i++) { Serial.print((char)payload[i]); } Serial.println(); // Switch on the LED if an 1 was received as first character if ((char)payload[0] == 'f') { digitalWrite(Relay1, LOW); // Turn the LED on (Note that LOW is the voltage level // but actually the LED is on; this is because // it is active low on the ESP-01) } else { digitalWrite(Relay1, HIGH); // Turn the LED off by making the voltage HIGH } } else { Serial.println("unsubscribed topic"); } } // Connecting to MQTT broker void reconnect() { // Loop until we're reconnected while (!client.connected()) { Serial.print("Attempting MQTT connection..."); // Create a random client ID String clientId = "ESP8266Client-"; clientId += String(random(0xffff), HEX); // Attempt to connect if (client.connect(clientId.c_str() , username, pass)) { Serial.println("connected"); // Once connected, publish an announcement... client.publish("outTopic", "hello world"); // ... and resubscribe client.subscribe(sub1); } else { Serial.print("failed, rc="); Serial.print(client.state()); Serial.println(" try again in 5 seconds"); // Wait 5 seconds before retrying delay(5000); } } } void setup() { pinMode(Relay1, OUTPUT); Serial.begin(115200); setup_wifi(); client.setServer(mqtt_server, 1883); client.setCallback(callback); } void loop() { if (!client.connected()) { reconnect(); } client. Loop(); } After writing the code, upload it to your ESP32 board by selecting the right board and port from the Tools menu and clicking the upload button. Step 5: Create Node-RED Flow The Node-RED flow will do the following tasks: Connect to the MQTT broker on Raspberry Pi Subscribe to a topic named “output” Publish messages “true” or “false” to a topic named “output” Create a dashboard with a button and a text node You can create the Node-RED flow by dragging and dropping nodes from the palette and connecting them with wires. You can also import the flow from this link or use the JSON code below: [ { "id": "eb8f9c0d054be30c", "type": "tab", "label": "Flow 2", "disabled": false, "info": "", "env": [] }, { "id": "4ce6cd876fd5441f", "type": "mqtt out", "z": "eb8f9c0d054be30c", "name": "", "topic": "output", "qos": "", "retain": "", "respTopic": "", "contentType": "", "userProps": "", "correl": "", "expiry": "", "broker": "6d40b7b21c734b53", "x": 870, "y": 240, "wires": [] }, { "id": "974a7a8bb6db9bf9", "type": "mqtt in", "z": "eb8f9c0d054be30c", "name": "", "topic": "output", "qos": "2", "datatype": "auto-detect", "broker": "6d40b7b21c734b53", "nl": false, "rap": true, "rh": 0, "inputs": 0, "x": 670, "y": 320, "wires": [ [ "d0dc7378c7bfb03b", "f1219a2eeabe825f" ] ] }, { "id": "d0dc7378c7bfb03b", "type": "debug", "z": "eb8f9c0d054be30c", "name": "debug 4", "active": true, "tosidebar": true, "console": false, "tostatus": false, "complete": "payload", "targetType": "msg", "statusVal": "", "statusType": "auto", "x": 880, "y": 320, "wires": [] }, { "id": "6bd227b280e372b7", "type": "ui_switch", "z": "eb8f9c0d054be30c", "name": "", "label": "Light One", "tooltip": "", "group": "cd687a95.00e108", "order": 0, "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": 680, "y": 240, "wires": [ [ "4ce6cd876fd5441f" ] ] }, { "id": "f1219a2eeabe825f", "type": "ui_text", "z": "eb8f9c0d054be30c", "group": "cd687a95.00e108", "order": 1, "width": "6", "height": "2", "name": "", "label": "Status : ", "format": "{{msg.payload}}", "layout": "row-center", "x": 1060, "y": 320, "wires": [] }, { "id": "6d40b7b21c734b53", "type": "mqtt-broker", "name": "Qubitro Downlink", "broker": "broker.qubitro.com", "port": "1883", "clientid": "", "autoConnect": true, "usetls": false, "protocolVersion": "4", "keepalive": "60", "cleansession": true, "autoUnsubscribe": true, "birthTopic": "r43MsJYzcVwZtUXVfZo6XD0Ym7CRegewPQXMt$ho", "birthQos": "0", "birthPayload": "", "birthMsg": {}, "closeTopic": "", "closeQos": "0", "closePayload": "", "closeMsg": {}, "willTopic": "", "willQos": "0", "willPayload": "", "willMsg": {}, "userProps": "", "sessionExpiry": "" }, { "id": "cd687a95.00e108", "type": "ui_group", "name": "ESP32 Home 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 } ] The input switch will send "true" when it is on, and it will send "false" when it triggers off. Then click on the Qubitro uplink pallet and edit the property. Here you need to replace your connection details and credentials. Next, just deploy the flow. And navigate to the /ui of the node-red server. Here you can toggle the switch to turn the lead on and off. Also, open the serial monitor and check the node-red response. Conclusion: In this tutorial, we have seen how to control the LED with Node-Red and MQTT Server.

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.