Introduction: Control Switch Over Internet With BLYNK

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Yello... Yello...Yello...! Today, it's time for smart switch which we are going to control over internet using our very precious BLYNK app. Cool!

The 5V relay connected to D5 pin of NodeMCU goes ON when D5 pin is set LOW and relay goes OFF when D5 pin is set HIGH.

We are simply going to set D5 pin HIGH to turn ON the appliance and D5 as LOW to turn OFF the appliance, considering the neutral wire is passing through the NC and COM of the relay.

Step 1: What Do We Need?

  • Hardware:
    • 5V relay
    • NodeMCU
    • Jumper wires
    • Breadboard
    • 3V3 and 5V power source
    • Electrical Wires
  • Software:
    • Arduino IDE
    • BLYNK app

Step 2: Circuit and Connections

  • D5 pin of NodeMCU connects to IN1 pin of 5V relay.
  • 3V3 of NodeMCU connects to 3V3 power source and GND to GND.
  • Vcc of relay connects to 5V source and GND to GND.
  • Live wire is connected directly to appliance.
  • Neutral wire from source comes to relay NC pin and another wire goes out from COM pin which is connected to the appliance.

Technically, we are connecting our switch on the neutral wire of the appliance, which is turning ON/OFF the appliance. Simple!

Step 3: Blynk Setup

  • Create a New Project in BLYNK app.
  • Write Project Name and Select NodeMCU from dropdown.
  • An AUTH token will be sent to your registered email, note this down.
  • Tap on the screen and add a Button.Tap on the Widget and select D5 pin, then change MODE to SWITCH.

Step 4: Code

We have completed the circuit and set up our BLYNK. Let's do some coding.

#define BLYNK_PRINT Serial 
#include <ESP8266Wifi.h>
#include <BlynkSimpleEsp8266.h> // You should get Auth Token in the Blynk App. // Go to the Project Settings (nut icon). char auth[] = "YOUR_AUTH_ID"; // Your WiFi credentials. // Set password to " " for open networks. char ssid[] = "WIFI_SSID"; char pass[] = "WIFI_PASSWORD"; void setup() { // Debug console Serial.begin(115200); Blynk.begin(auth, ssid, pass); // You can also specify server: //Blynk.begin(auth, ssid, pass, "", 8442); //Blynk.begin(auth, ssid, pass, IPAddress(192,168,1,100), 8442); } void loop() {; }

Make sure to change the AUTH_KEY, SSID and PASSWORD before uploading the code to NodeMCU.

Step 5: Upload and Play

Connect NodeMCU using the MicroUSB cable and upload the code using Arduino IDE.

Once uploaded, click Play button on the BLYNK app and start turning ON/OFF your devices from anywhere in the world.

Oh Yeah!

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Keep breaking, keep making!