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TempMonSub

+#include <ArduinoMqttClient.h>
+#include <WiFiNINA.h>
+#include "arduino_secrets.h"
+
+///////please enter your sensitive data in the Secret tab/arduino_secrets.h
+char ssid[] = SECRET_SSID;        // your network SSID
+char pass[] = SECRET_PASS;    // your network password
+
+WiFiClient wifiClient;
+MqttClient mqttClient(wifiClient);
+
+const char broker[] = "test.mosquitto.org";
+int        port     = 1883;
+const char topic[]  = "st_john_iot_temperature_value_topic";
+
+
+void setup() {
+  // put your setup code here, to run once:
+  //Initialize serial and wait for port to open:
+  Serial.begin(9600);
+  while (!Serial) {
+    ; // wait for serial port to connect. Needed for native USB port only
+  }
+  // attempt to connect to Wifi network:
+  Serial.print("Attempting to connect to SSID: ");
+  Serial.println(ssid);
+  while (WiFi.begin(ssid, pass) != WL_CONNECTED) {
+    // failed, retry
+    Serial.print(".");
+    delay(5000);
+  }
+
+  Serial.println("You're connected to the network");
+  Serial.println();
+
+  Serial.print("Attempting to connect to the MQTT broker: ");
+  Serial.println(broker);
+
+  if (!mqttClient.connect(broker, port)) {
+    Serial.print("MQTT connection failed! Error code = ");
+    Serial.println(mqttClient.connectError());
+
+    while (1);
+  }
+
+  Serial.println("You're connected to the MQTT broker!");
+  Serial.println();
+
+  // set the message receive callback
+  mqttClient.onMessage(onMqttMessage);
+
+  Serial.println("Subscribing to topic: ");
+  Serial.println(topic);
+  Serial.println();
+
+  // subscribe to a topic
+  mqttClient.subscribe(topic);
+
+  // topics can be unsubscribed using:
+  // mqttClient.unsubscribe(topic);
+
+  Serial.println("Topic: ");
+  Serial.println(topic);
+
+  Serial.println();
+}
+
+void loop() {
+  // put your main code here, to run repeatedly:
+  // call poll() regularly to allow the library to receive MQTT messages and
+  // send MQTT keep alive which avoids being disconnected by the broker
+  mqttClient.poll();
+}
+
+void onMqttMessage(int messageSize) {
+  // we received a message, print out the topic and contents
+  Serial.println("Recorded Temperature value is '");
+  Serial.println(mqttClient.messageTopic());
+
+  // use the Stream interface to print the contents
+  while (mqttClient.available()) {
+    Serial.print((char)mqttClient.read());
+  }
+  Serial.println();
+  Serial.println();
+}