ESP32/ESP8266 Relay toggle

Today we will talk about little different type of content than usual one. We will have some fun with ESP boards and a relay connected.

Steps to control a relay with ESP32/ESP8266:

1. Connect IN pin of relay module to GPIO (e.g., GPIO5)
2. Power module from 3.3V (with transistor if needed)
3. Set GPIO HIGH/LOW in code to open/close relay
4. Upload code and test switching

We will configure ESP to connect to WIFI, bring up a basic webserver and then create a route to toggle our relay and get relay status so sketch is the following one:

// Load libraries
#ifdef ESP32
  #include <WiFi.h>
  #include <AsyncTCP.h>
#else
  #include <ESP8266WiFi.h>
  #include <ESPAsyncTCP.h>
#endif
#include <ESPAsyncWebServer.h>
  
// Declare WIFI and relay pin vars
const char* ssid = "WIFI_NAME";
const char* password =  "WIFI_PASSWORD";
int relayPin = 4;
  
// Configure webserver port
AsyncWebServer server(80);
  
void setup(){
  
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, LOW);
  
  // Configure serial communication
  Serial.begin(115200);
  
  // Start WIFI
  WiFi.begin(ssid, password);
  
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi..");
  }
  
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
  
  // Configure route to toggle relay
  server.on("/toggle", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send(200, "text/plain","ok");
    digitalWrite(relayPin, !digitalRead(relayPin));
  });
  
  // Configure route to get relay state
  server.on("/status", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send(200, "text/plain", String(digitalRead(relayPin)));
  });
  
  // Start webserver
  server.begin();
}
  
void loop(){}

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