Change OLED to listen on MQTT

src/main.cpp

@@ -14,6 +14,16 @@
 #include <ESPmDNS.h>
 #include <Update.h>
 #include <uri/UriBraces.h>
+#include <PubSubClient.h>
+#include <ArduinoJson.h>
+
+const char* mqtt_server = "mqtt.ddns.kawomi.com";
+
+WiFiClient espClient;
+PubSubClient client(espClient);
+unsigned long lastMsg = 0;
+#define MSG_BUFFER_SIZE	(50)
+char msg[MSG_BUFFER_SIZE];
 
 const char* host = "esp32oled";
 const char* ssid = "JoNelsDarlings";
@@ -114,6 +124,58 @@ const char* serverIndex =
  "</script>";
 
 
+void reconnect() {
+  // Loop until we're reconnected
+  while (!client.connected()) {
+    Serial.print("Attempting MQTT connection...");
+    // Create a random client ID
+    String clientId = "ESP32Client-";
+    clientId += String(random(0xffff), HEX);
+    // Attempt to connect
+    if (client.connect(clientId.c_str())) {
+      Serial.println("MQTT connected");
+      client.publish("OLED", "Connected");
+      client.subscribe("Address/Livorno/Office/OLED/setText");
+    } else {
+      Serial.print("MQTT failed, rc=");
+      Serial.print(client.state());
+      Serial.println(" try again in 5 seconds");
+      // Wait 5 seconds before retrying
+      delay(5000);
+    }
+  }
+}
+
+void callback(char* topic, byte* payload, unsigned int length) {
+  Serial.print("Message arrived [");
+  Serial.print(topic);
+ 
+  String recBuf="";
+  Serial.print("] ");
+  for (int i = 0; i < length; i++) {
+    recBuf += (char)payload[i];
+  }
+  Serial.println(recBuf);
+
+  StaticJsonDocument<1024> jsonDoc;
+  deserializeJson(jsonDoc,recBuf);
+  const char* theText=jsonDoc["text"];
+  int theSize=jsonDoc["size"];
+
+  display.setCursor(40, 0);
+  display.setTextSize(9);
+  display.print("#");
+  display.display();
+  delay(500);
+
+  display.setCursor(0, 0);
+  display.setTextSize(theSize);
+  display.clearDisplay();
+  display.print(theText);
+  display.display();
+}
+
+
 void writeToOled(String text){
   display.clearDisplay();
   display.setTextColor(WHITE);
@@ -128,7 +190,9 @@ void writeToOled(String text){
  */
 void setup(void) {
   Serial.begin(9600);
+  delay(2000);
 
+  Serial.println("STARTUP");
   if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
     Serial.println(F("SSD1306 allocation failed"));
     for(;;);
@@ -137,6 +201,7 @@ void setup(void) {
   
   writeToOled("Startup");
 
+  randomSeed(micros());
   // Connect to WiFi network
   WiFi.begin(ssid, password);
   Serial.println("");
@@ -215,6 +280,9 @@ void setup(void) {
   });
   server.begin();
 
+  client.setServer(mqtt_server, 1883);
+  client.setCallback(callback);
+
   writeToOled("Ready.");
 
 }
@@ -222,4 +290,10 @@ void setup(void) {
 void loop(void) {
   server.handleClient();
   delay(1);
+
+  if (!client.connected()) {
+    reconnect();
+  }
+  client.loop();
+
 }