Discussion :

[f-leb]

Bonjour,

Oui, et c'est aussi la version 3.1.1 de MQTT qui est utilisée par défaut par la bibliothèque PubSubClient.

J'ai retrouvé mon ESP32 et j'ai réussi à me connecter à Thingspeak au channel public https://thingspeak.com/channels/357142 avec le code suivant à adapter :

Code :

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/*
  MqttClient - WiFi Simple Receive
 
  This example connects to a MQTT broker and subscribes to a single topic.
  When a message is received it prints the message to the Serial Monitor.
 
  This example code is in the public domain.
*/
 
#include <PubSubClient.h>
#include <WiFi.h>
 
#include "arduino_secrets.h"
 
void WIFISetUp(void);
void mqttCallback(char *topic, byte *payload, unsigned int length);
 
///////please enter your sensitive data in the Secret tab/arduino_secrets.h
char ssid[] = SECRET_SSID;  // your network SSID (name)
char pass[] = SECRET_PASS;  // your network password (use for WPA, or use as key for WEP)
 
WiFiClient wifiClient;
PubSubClient mqttClient(wifiClient);
 
const char mqttBroker[] = "mqtt3.thingspeak.com";
int mqttPort = 1883;
const char mqttTopic[] = "channels/357142/subscribe";
 
const char mqttClientID[] = "IywXBgxxxxxxxxxxxxxxxxxxx";
const char mqttUsername[] = "IywXBgxxxxxxxxxxxxxxxxxxx";
const char mqttPassword[] = "B7V0ujgxxxxxxxxxxxxxxxxxx";
 
void setup() {
 
  Serial.begin(115200);
  while (!Serial) {
    ;
  }
 
  // attempt to connect to WiFi network:
  Serial.print("Attempting to connect to WPA SSID: ");
  Serial.println(ssid);
 
  WIFISetUp();
  Serial.println("You're connected to the network");
  Serial.println();
 
  mqttClient.setServer(mqttBroker, mqttPort);
  mqttClient.setCallback(mqttCallback);
  mqttClient.setBufferSize(512);
 
  while (!mqttClient.connected()) {
    Serial.print("Attempting to connect to the MQTT broker: ");
    Serial.println(mqttBroker);
    if (mqttClient.connect(mqttClientID, mqttUsername, mqttPassword)) {
      Serial.println("You're connected to the MQTT broker!");
      if (mqttClient.subscribe(mqttTopic)) {
        Serial.print("Subscribing to topic ");
        Serial.print(mqttTopic);
        Serial.println(": success");
        Serial.println("Waiting for messages on topic...");
      } else {
        Serial.println("Subscribing to topic: failed");
      }
    } else {
      Serial.print("Failed, state=");
      Serial.print(mqttClient.state());
      Serial.println(" New try in 5s...");
      delay(5000);
    }
  }
}
 
void loop() {
  mqttClient.loop();
}
 
void mqttCallback(char *topic, byte *payload, unsigned int length) {
  Serial.print("Message arrived in topic: ");
  Serial.println(topic);
  Serial.print("Message:");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
  Serial.println("-----------------------");
}
 
void WIFISetUp(void) {
  // Set WiFi to station mode and disconnect from an AP if it was previously connected
  WiFi.disconnect(true);
  delay(100);
  WiFi.mode(WIFI_STA);
  WiFi.setAutoReconnect(true);
  WiFi.begin(ssid, pass);  //fill in "Your WiFi SSID","Your Password"
  delay(100);
 
  byte count = 0;
  while (WiFi.status() != WL_CONNECTED && count < 15) {
    count++;
    delay(2000);
    Serial.println("Connecting...");
  }
 
  if (WiFi.status() == WL_CONNECTED) {
    Serial.println("Connecting...OK.");
    delay(500);
  } else {
    Serial.println("Connecting...Failed");
    while (1)
      ;
  }
  Serial.println("WIFI Setup done");
  delay(500);
}

arduino_secrets.h

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#define SECRET_SSID "your SSID"
#define SECRET_PASS "your password"

Dans le terminal série, j'ai bien les messages qui arrivent :

Code :

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Connecting...
Connecting...OK.
WIFI Setup done
You're connected to the network
 
Attempting to connect to the MQTT broker: mqtt3.thingspeak.com
You're connected to the MQTT broker!
Subscribing to topic channels/357142/subscribe: success
Waiting for messages on topic...
Message arrived in topic: channels/357142/subscribe
Message:{"channel_id":357142,"created_at":"2024-08-06T13:52:20+02:00","entry_id":290735,"field1":"3.3","field2":"4.0","field3":"32.360","field4":"978.435","field5":"34.546","field6":null,"field7":"43.715","field8":"5.543","latitude":null,"longitude":null,"elevation":null,"status":"13:52:20: new data"}
-----------------------
Message arrived in topic: channels/357142/subscribe
Message:{"channel_id":357142,"created_at":"2024-08-06T14:04:26+02:00","entry_id":290736,"field1":"2.8","field2":"3.1","field3":"33.383","field4":"978.354","field5":"33.946","field6":null,"field7":"44.298","field8":"5.615","latitude":null,"longitude":null,"elevation":null,"status":"14:04:26: new data"}
-----------------------

La ligne mqttClient.setBufferSize(512); est importante, par défaut la taille du buffer est de 256 octets et comme le message est plus long, je ne voyais aucun message arriver

[cobra38]

Grand merci f-leb

je reçois les données brutes de Thinkspeack maintenant grâce à ton croquis

Sans vouloir abuser , un conseil pour "découper" la chaîne de caractères afin d'exploiter ces données ?

[f-leb]

Je n'ai pas encore regardé, mais comme la chaîne de caractères est au format JSON, je pense à cette bibliothèque prévue pour :

Code :

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#include <ArduinoJson.h>      // https://github.com/bblanchon/ArduinoJson

Tu la trouveras facilement dans le gestionnaire de bibliothèques de l'EDI Arduino...

[f-leb]

Par exemple, pour récupérer le champ field7 qui est une température, tu peux compléter la fonction callback :

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// ...
#include <ArduinoJson.h>      // https://github.com/bblanchon/ArduinoJson
 
// ...
 
void mqttCallback(char *topic, byte *payload, unsigned int length) {
  // ...
 
  // voir https://arduinojson.org/v7/tutorial/deserialization/
  JsonDocument doc;
  deserializeJson(doc, (unsigned char*)payload);
  const char* temp = doc["field7"];
  Serial.print("temperature = ");
  Serial.println(temp);
 
  // ...
}

Code :

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Message arrived in topic: channels/357142/subscribe
Message:{"channel_id":357142,"created_at":"2024-08-07T12:13:15+02:00","entry_id":290846,"field1":"5.6","field2":"7.9","field3":"27.241","field4":"980.199","field5":"57.435","field6":null,"field7":"39.367","field8":"4.685","latitude":null,"longitude":null,"elevation":null,"status":"12:13:15: new data"}
 
temperature = 39.367
-----------------------
Message arrived in topic: channels/357142/subscribe
Message:{"channel_id":357142,"created_at":"2024-08-07T12:25:20+02:00","entry_id":290847,"field1":"5.2","field2":"5.8","field3":"26.579","field4":"980.320","field5":"62.674","field6":null,"field7":"38.336","field8":"4.496","latitude":null,"longitude":null,"elevation":null,"status":"12:25:20: new data"}
 
temperature = 38.336
-----------------------

[cobra38]

Super ! f-leb

çà fonctionne très bien , il me reste à traiter l'affichage TFT maintenant

Merci mille fois pour le coup de main et pour ta patience

je pense que je vais clôturer le post

Cordialement
pascal