Wie macht man das mit LWT in C/C++ richtig ?

[TomLee]

Da ich meinen QRCode-Scanner-Code irgendwie zusammenkopiert hab (da ich mich mit C/C++ Programmierung bisher nur wenig beschäftigt habe) und kein reconnect der Wifi-Verbindung eingebaut hab, beschäftige ich mich gerade mit den Basics .


Ich fänds toll wenn mein QRCode-Scanner-Device später auch seinen "Online-Status" mitteilt, darum hab ich den Anhang aus dem Link oben so ergänzt/bearbeitet:

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <PubSubClient.h>

#define TOPIC_IN  "esdemo/in"
#define TOPIC_LWT "espdemo/LWT"

const char* ssid        = "<SSID>";
const char* password    = "<PWD>";

const char* mqtt_server = "IP";
const int mqttPort = 1883;
const char* mqttUser = "USRNAME";
const char* mqttPassword = "PWD";

byte willQoS = 0;
const char* willTopic = "espdemo/LWT";
const char* willMessage = "offline";
boolean willRetain = false;


void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload);
  }
  Serial.println();

  payload[length] = '\0';
  if (strcmp(topic,TOPIC_IN)==0){

//    String payload_str = (char *) payload;
//    setMode(payload_str.substring(6,7).toInt(),payload_str.substring(8,9).toInt());
  }
}

WiFiClient espClient;
PubSubClient client(mqtt_server,mqttPort,callback,espClient);

void setup_wifi() {
  Serial.println();
  Serial.printf("Connecting to %s ",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());
  Serial.println("");
}

void reconnect() {
  while (!client.connected()) {
    String clientId = "ESP-QRCODE";
//    clientId += String(random(0xffff), HEX);
    Serial.print("Attempting MQTT connection to ");
    Serial.print(mqtt_server);
    Serial.print(" as ");
    Serial.println(clientId.c_str());
    if (client.connect(clientId.c_str(), mqttUser, mqttPassword, willTopic, willQoS, willRetain, willMessage)) {
      clientId += " connected";
      Serial.println(clientId);
      Serial.println();
//      client.publish(TOPIC_OUT,clientId.c_str());
    client.publish(TOPIC_LWT,"online");
      client.subscribe(TOPIC_IN);
    } else {
      Serial.print(clientId);
      Serial.print(" failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void setup() {
  Serial.begin(115200);
  setup_wifi();
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  delay(100);
}

Ich bin mir unsicher bei dem publish von dem "online".
Gibt man wie hier keine Keep alive Zeit an, erkennt der MQTT2-Server nach 30 Sekunden das der Client nicht mehr da ist und setzt den "offline"-Wert.
Das mit der Zufallszahl bei der ClientID hab ich ausgeknipst, weil ich denke eine feste CID macht sich besser.

Kann hier irgendwer mit Erfahrung in der Materie dazu was sagen ob man das mit dem LWT so machen kann oder/bzw. wie man es richtig macht ?

Gruß

Thomas

[xenos1984]

Sieht auf den ersten Blick richtig aus.

[TomLee]

Danke für das drüberschauen.

OT:

So stell ich mir meinen endgültigen QRCodescanner-Code vor (ungetestet, bisher noch nicht geflasht, aber schon kompiliert):

Code Auswählen Erweitern

#include <Arduino.h>
#include <ESP32QRCodeReader.h>
#include <WiFi.h>
#include <WiFiClient.h>
#include <PubSubClient.h>
#include <Adafruit_NeoPixel.h>

// WS2812B
#define NUM_PIXELS 1
#define PIN 2

// MQTT Topics
#define TOPIC_IN  "house/in"
#define TOPIC_LWT "house/lwt"
#define TOPIC_QRCODE "house/qrcode"

// WiFi
const char* ssid        = "<SSID>";
const char* password    = "<PWD>";

// MQTT
const char* mqtt_server = "<IP>";
const int mqttPort = 1883;
const char* mqttUser = "<NAME>";
const char* mqttPassword = "<PWD>";

// MQTT LWT
byte willQoS = 0;
const char* willTopic = "house/LWT";
const char* willMessage = "offline";
boolean willRetain = false;


ESP32QRCodeReader reader(CAMERA_MODEL_AI_THINKER);

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();

  payload[length] = '\0';
  if (strcmp(topic,TOPIC_IN)==0){

//    String payload_str = (char *) payload;
//    setMode(payload_str.substring(6,7).toInt(),payload_str.substring(8,9).toInt());
  }
}

WiFiClient espClient;
PubSubClient client(mqtt_server,mqttPort,callback,espClient);
// declare pixels
Adafruit_NeoPixel pixels(NUM_PIXELS, PIN, NEO_GRB + NEO_KHZ800);

void setup_wifi() {
  Serial.println();
  Serial.printf("Connecting to %s ",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());
  Serial.println("");
}

void reconnect() {
  while (!client.connected()) {
    String clientId = "ESP-QRCODE";
//    clientId += String(random(0xffff), HEX);
    Serial.print("Attempting MQTT connection to ");
    Serial.print(mqtt_server);
    Serial.print(" as ");
    Serial.println(clientId.c_str());
    if (client.connect(clientId.c_str(), mqttUser, mqttPassword, willTopic, willQoS, willRetain, willMessage)) {
      clientId += " connected";
      Serial.println(clientId);
      Serial.println();
//      client.publish(TOPIC_OUT,clientId.c_str());
    client.publish(TOPIC_LWT,"online");
      client.subscribe(TOPIC_IN);
    } else {
      Serial.print(clientId);
      Serial.print(" failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void onQrCodeTask(void *pvParameters)
{
  struct QRCodeData qrCodeData;

  while (true)
  {
    if (reader.receiveQrCode(&qrCodeData, 100))
    {
      Serial.println("Found QRCode");
      if (qrCodeData.valid)
      {
        Serial.print("Payload: ");
        Serial.println((const char *)qrCodeData.payload);
        client.publish(TOPIC_QRCODE, (const char *)qrCodeData.payload);
        pixels.setPixelColor(0, pixels.Color(0, 150, 0));  //green
        pixels.show();
        delay(2000);             // wait for 2000 milliseconds
        pixels.clear();
        pixels.show();
      }
      else
      {
        Serial.print("Invalid: ");
        Serial.println((const char *)qrCodeData.payload);
        pixels.setPixelColor(0, pixels.Color(150, 0, 0));  //red
        pixels.show();
        delay(200);             // wait for 2000 milliseconds
        pixels.clear();
        pixels.show();
      }
    }
    vTaskDelay(50 / portTICK_PERIOD_MS);
  }
}

void setup() {
  Serial.begin(115200);
  setup_wifi();
  pixels.begin();
    Serial.println();

  reader.setup();

  Serial.println("Setup QRCode Reader");

  reader.beginOnCore(1);

  Serial.println("Begin on Core 1");

  xTaskCreate(onQrCodeTask, "onQrCode", 4 * 1024, NULL, 4, NULL);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  delay(100);
}
Based on: https://www.makeuseof.com/scanning-qr-codes-with-esp32-cam

Used lib: https://github.com/alvarowolfx/ESP32QRCodeReader