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--- latinet:unicaes:workshops:communication-23 [2023/08/30 20:35] – jan.sonntag
+++ latinet:unicaes:workshops:communication-23 [2023/10/22 22:19] – [3. Our first MQTT Publish] rolf.becker
@@ Line 84: / Line 84: @@
 ===== 3. Our first MQTT Publish =====
 Stepping ahead, you'll have the chance to implement your first MQTT publish from the ESP8266. While the following example provides a static demonstration, we encourage you to take it a step further by incorporating one of the sensors available to you.
+PubSubClient Library: [[https://github.com/knolleary/pubsubclient|PubSubClient by knolleary]]
+<file c++ mqtt-publish.ino>
+/*
+ Basic ESP8266 MQTT example
+ This sketch demonstrates the capabilities of the pubsub library in combination
+ with the ESP8266 board/library.
+ It connects to an MQTT server then:
+  - publishes "hello world" to the topic defined as outTopic every two seconds
+ It will reconnect to the server if the connection is lost using a blocking
+ reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to
+ achieve the same result without blocking the main loop.
+*/
+#include <ESP8266WiFi.h>
+#include <PubSubClient.h>
+#define MSG_BUFFER_SIZE	(50)
+// Update these with values suitable for your network and mqtt broker
+const char* ssid = "";
+const char* password = "";
+const char* mqtt_server = "broker.hivemq.com";
+const char* outTopic = "unicaes/workshop/2023/jan";
+const char* inTopic = "unicaes/workshop/2023/to-jan";
+// Set up of some needed variables
+WiFiClient espClient;
+PubSubClient client(espClient);
+unsigned long lastMsg = 0;
+char msg[MSG_BUFFER_SIZE];
+int value = 0;
+void setup_wifi() {
+  delay(10);
+  // We start by connecting to a WiFi network
+  Serial.println();
+  Serial.print("Connecting to ");
+  Serial.println(ssid);
+  WiFi.mode(WIFI_STA);
+  WiFi.begin(ssid, password);
+  while (WiFi.status() != WL_CONNECTED) {
+    delay(500);
+    Serial.print(".");
+  }
+  randomSeed(micros());
+  Serial.println("");
+  Serial.println("WiFi connected");
+  Serial.println("IP address: ");
+  Serial.println(WiFi.localIP());
+}
+void reconnect() {
+  // Loop until we're reconnected
+  while (!client.connected()) {
+    Serial.print("Attempting MQTT connection...");
+    // Create a random client ID
+    String clientId = "ESP8266Client-";
+    clientId += String(random(0xffff), HEX);
+    // Attempt to connect
+    if (client.connect(clientId.c_str())) {
+      Serial.println("connected");
+      // Once connected, publish an announcement...
+      client.publish(outTopic, "hello world");
+    } else {
+      Serial.print("failed, rc=");
+      Serial.print(client.state());
+      Serial.println(" try again in 5 seconds");
+      // Wait 5 seconds before retrying
+      delay(5000);
+    }
+  }
+}
+void setup() {
+  pinMode(BUILTIN_LED, OUTPUT);     // Initialize the BUILTIN_LED pin as an output
+  Serial.begin(115200);
+  setup_wifi();
+  client.setServer(mqtt_server, 1883);
+}
+void loop() {
+  if (!client.connected()) {
+    reconnect();
+  }
+  client.loop();
+  unsigned long now = millis();
+  if (now - lastMsg > 2000) {
+    lastMsg = now;
+    ++value;
+    snprintf (msg, MSG_BUFFER_SIZE, "hello world #%ld", value);
+    Serial.print("Publish message: ");
+    Serial.println(msg);
+    client.publish(outTopic, msg);
+  }
+}
+</file>
 ===== 4. Subscribe =====
@@ Line 109: / Line 217: @@
 // Update these with values suitable for your network and mqtt broker
-const char* ssid = "iotlab";
+const char* ssid = "";
-const char* password = "iotlab18";
+const char* password = "";
 const char* mqtt_server = "broker.hivemq.com";