ESP32 version that could work

examples/simple-client/simple-client.ino

@@ -1,10 +1,12 @@
-#include <ESP8266WiFi.h>
 #include "TinyMqtt.h"   // https://github.com/hsaturn/TinyMqtt
 
 /** Simple Client
   *
 	* This is the simplest Mqtt client configuration
 	*
+	* 1 - edit my_credentials.h to setup wifi essid/password
+	* 2 - change BROKER values (or keep emqx.io test broker)
+	*
 	* pro  - small memory footprint (both ram and flash)
 	*      - very simple to setup and use
 	*
@@ -13,6 +15,9 @@
 	*      - local publishes takes more time (because they go outside)
 	*/
 
+const char* BROKER = "broker.emqx.io";
+const uint16_t BROKER_PORT = 1883;
+
 #include <my_credentials.h>
 
 static float temp=19;
@@ -32,8 +37,7 @@ void setup()
 
   Serial << "Connected to " << ssid << "IP address: " << WiFi.localIP() << endl;  
 
-	client.connect("192.168.1.40", 1883);	// Put here your broker ip / port
+	client.connect(BROKER, BROKER_PORT);	// Put here your broker ip / port
-
 }
 
 void loop()

src/TinyMqtt.h

@@ -1,6 +1,10 @@
 #pragma once
-#include <ESP8266WiFi.h>
+#ifdef ESP8266
-#include <ESPAsyncTCP.h>
+	#include <ESPAsyncTCP.h>
+#elif defined(ESP32)
+	#include <WiFi.h>
+	#include <AsyncTCP.h> // https://github.com/me-no-dev/AsyncTCP
+#endif
 #include <vector>
 #include <set>
 #include <string>