v1.4.0 to add Teensy41 and QNEthernet

### Releases v1.4.0

1. Add support to **Teensy 4.1 using QNEthernet Library**
2. Add example for `QNEthernet`

Author: khoih-prog

examples/QNEthernet/FullyFeatured_QNEthernet/FullyFeatured_QNEthernet.ino

@@ -0,0 +1,216 @@
+/****************************************************************************************************************************
+  FullyFeatured_QNEthernet.ino
+  
+  AsyncMqttClient_Generic is a library for ESP32, ESP8266, Protenta_H7, Teensy41_QNEthernet_PubF7, etc. with current AsyncTCP support
+  
+  Based on and modified from :
+  
+  1) async-mqtt-client (https://github.com/marvinroger/async-mqtt-client)
+  
+  Built by Khoi Hoang https://github.com/khoih-prog/AsyncMqttClient_Generic
+ *****************************************************************************************************************************/
+
+#include "defines.h"
+
+// Check connection every 1s
+#define MQTT_CHECK_INTERVAL_MS     1000 
+
+#include <AsyncMqtt_Generic.h>
+
+#include <Ticker.h>                   // https://github.com/sstaub/Ticker
+
+//#define MQTT_HOST         IPAddress(192, 168, 2, 110)
+#define MQTT_HOST         "broker.emqx.io"        // Broker address
+#define MQTT_PORT         1883
+
+const char *PubTopic  = "async-mqtt/Teensy41_QNEthernet_Pub";               // Topic to publish
+
+AsyncMqttClient mqttClient;
+
+void connectToMqtt();
+void connectToMqttCheck();
+
+// Repeat forever, millis() resolution
+Ticker connectToMqttTicker(connectToMqttCheck, MQTT_CHECK_INTERVAL_MS, 0, MILLIS); 
+
+bool connectedEthernet  = false;
+bool connectedMQTT      = false;
+
+void connectToMqttCheck()
+{
+  if (Ethernet.linkStatus() == LinkON)
+  {
+    //Ethernet.maintain();
+
+    if (!connectedMQTT)
+    {
+      mqttClient.connect();
+    }
+
+    if (!connectedEthernet)
+    {
+      Serial.println("Ethernet reconnected.");
+      connectedEthernet = true;
+    }
+  }
+  else
+  {
+    if (connectedEthernet)
+    {
+      Serial.println("Ethernet disconnected");      
+      connectedEthernet = false;
+    }
+  }
+}
+
+void connectToMqtt()
+{
+  Serial.println("Connecting to MQTT...");
+  mqttClient.connect();
+}
+
+void printSeparationLine()
+{
+  Serial.println("************************************************");
+}
+
+void onMqttConnect(bool sessionPresent) 
+{
+  Serial.print("Connected to MQTT broker: "); Serial.print(MQTT_HOST);
+  Serial.print(", port: "); Serial.println(MQTT_PORT);
+  Serial.print("PubTopic: "); Serial.println(PubTopic);
+
+  connectedMQTT = true;
+  
+  printSeparationLine();
+  Serial.print("Session present: "); Serial.println(sessionPresent);
+  
+  uint16_t packetIdSub = mqttClient.subscribe(PubTopic, 2);
+  Serial.print("Subscribing at QoS 2, packetId: "); Serial.println(packetIdSub);
+  
+  mqttClient.publish(PubTopic, 0, true, "Teensy41_QNEthernet_Pub Test1");
+  Serial.println("Publishing at QoS 0");
+  
+  uint16_t packetIdPub1 = mqttClient.publish(PubTopic, 1, true, "Teensy41_QNEthernet_Pub Test2");
+  Serial.print("Publishing at QoS 1, packetId: "); Serial.println(packetIdPub1);
+  
+  uint16_t packetIdPub2 = mqttClient.publish(PubTopic, 2, true, "Teensy41_QNEthernet_Pub Test3");
+  Serial.print("Publishing at QoS 2, packetId: "); Serial.println(packetIdPub2);
+
+  printSeparationLine();
+}
+
+void onMqttDisconnect(AsyncMqttClientDisconnectReason reason)
+{
+  (void) reason;
+
+  connectedMQTT = false;
+  
+  Serial.println("Disconnected from MQTT.");
+}
+
+void onMqttSubscribe(const uint16_t& packetId, const uint8_t& qos)
+{
+  Serial.println("Subscribe acknowledged.");
+  Serial.print("  packetId: "); Serial.println(packetId);
+  Serial.print("  qos: ");      Serial.println(qos);
+}
+
+void onMqttUnsubscribe(const uint16_t& packetId)
+{
+  Serial.println("Unsubscribe acknowledged.");
+  Serial.print("  packetId: "); Serial.println(packetId);
+}
+
+void onMqttMessage(char* topic, char* payload, const AsyncMqttClientMessageProperties& properties, 
+                   const size_t& len, const size_t& index, const size_t& total)
+{
+  char message[len + 1];
+
+  memcpy(message, payload, len);
+  message[len] = 0;
+  
+  Serial.println("Publish received.");
+  Serial.print("  topic: ");    Serial.println(topic);
+  Serial.print("  message: ");  Serial.println(message);
+  Serial.print("  qos: ");      Serial.println(properties.qos);
+  Serial.print("  dup: ");      Serial.println(properties.dup);
+  Serial.print("  retain: ");   Serial.println(properties.retain);
+  Serial.print("  len: ");      Serial.println(len);
+  Serial.print("  index: ");    Serial.println(index);
+  Serial.print("  total: ");    Serial.println(total);
+}
+
+void onMqttPublish(const uint16_t& packetId)
+{
+  Serial.println("Publish acknowledged.");
+  Serial.print("  packetId: "); Serial.println(packetId);
+}
+
+void setup()
+{
+  Serial.begin(115200);
+  while (!Serial);
+
+  delay(500);
+
+  Serial.print("\nStarting FullyFeatured_QNEthernet on "); Serial.println(BOARD_NAME);
+  Serial.println(ASYNC_MQTT_GENERIC_VERSION);
+
+#if USING_DHCP
+  // Start the Ethernet connection, using DHCP
+  Serial.print("Initialize Ethernet using DHCP => ");
+  Ethernet.begin();
+#else
+  // Start the Ethernet connection, using static IP
+  Serial.print("Initialize Ethernet using static IP => ");
+  Ethernet.begin(myIP, myNetmask, myGW);
+  Ethernet.setDNSServerIP(mydnsServer);
+#endif
+
+  if (!Ethernet.waitForLocalIP(5000))
+  {
+    Serial.println(F("Failed to configure Ethernet"));
+
+    if (!Ethernet.linkStatus())
+    {
+      Serial.println(F("Ethernet cable is not connected."));
+    }
+
+    // Stay here forever
+    while (true)
+    {
+      delay(1);
+    }
+  }
+  else
+  {
+    Serial.print(F("Connected! IP address:")); Serial.println(Ethernet.localIP());
+  }
+
+#if USING_DHCP
+  delay(1000);
+#else  
+  delay(2000);
+#endif  
+
+  connectedEthernet = true;
+
+  mqttClient.onConnect(onMqttConnect);
+  mqttClient.onDisconnect(onMqttDisconnect);
+  mqttClient.onSubscribe(onMqttSubscribe);
+  mqttClient.onUnsubscribe(onMqttUnsubscribe);
+  mqttClient.onMessage(onMqttMessage);
+  mqttClient.onPublish(onMqttPublish);
+
+  mqttClient.setServer(MQTT_HOST, MQTT_PORT);
+
+  connectToMqttTicker.start(); //start the ticker.
+
+  connectToMqtt();
+}
+
+void loop()
+{
+  connectToMqttTicker.update(); //update the ticker.
+}

examples/QNEthernet/FullyFeatured_QNEthernet/defines.h

@@ -0,0 +1,43 @@
+/****************************************************************************************************************************
+  defines.h
+  AsyncMqttClient_Generic is a library for ESP32, ESP8266, Protenta_H7, STM32F7, etc. with current AsyncTCP support
+
+  Based on and modified from :
+
+  1) async-mqtt-client (https://github.com/marvinroger/async-mqtt-client)
+
+  Built by Khoi Hoang https://github.com/khoih-prog/AsyncMqttClient_Generic
+ ***************************************************************************************************************************************/
+
+#ifndef defines_h
+#define defines_h
+
+#if !( defined(CORE_TEENSY) && defined(__IMXRT1062__) && defined(ARDUINO_TEENSY41) )
+#error Only Teensy 4.1 supported
+#endif
+
+// Debug Level from 0 to 4
+#define _TEENSY41_ASYNC_TCP_LOGLEVEL_       1
+#define _ASYNC_MQTT_LOGLEVEL_               4
+
+#define SHIELD_TYPE     "Teensy4.1 QNEthernet"
+
+#include "QNEthernet.h"       // https://github.com/ssilverman/QNEthernet
+using namespace qindesign::network;
+
+#if (_ASYNC_MQTT_LOGLEVEL_ > 3)
+#warning Using QNEthernet lib for Teensy 4.1. Must also use Teensy Packages Patch or error
+#endif
+#define USING_DHCP            true
+//#define USING_DHCP            false
+
+#if !USING_DHCP
+// Set the static IP address to use if the DHCP fails to assign
+IPAddress myIP(192, 168, 2, 222);
+IPAddress myNetmask(255, 255, 255, 0);
+IPAddress myGW(192, 168, 2, 1);
+//IPAddress mydnsServer(192, 168, 2, 1);
+IPAddress mydnsServer(8, 8, 8, 8);
+#endif
+
+#endif    //defines_h