Replace the MQTT client with a robust async option

include/wlan.h

@@ -2,14 +2,33 @@
 #define WLAN_H
 
 #include "config.h"
-#include <PubSubClient.h>
+#include <AsyncMqttClient.h>
+#include <ESP8266WiFi.h>
+#include <Ticker.h>
+
+static AsyncMqttClient mqtt_client;
+static Ticker mqtt_connection_timer, wlan_connection_timer;
+static WiFiEventHandler connection_handler, disconnection_handler;
+extern Config *config;
+
+void initialize_wlan();
+
+void initialize_mqtt();
+
+void connect_wlan();
+
+void connect_mqtt();
+
+void on_wlan_connection(const WiFiEventStationModeGotIP &event);
+
+void on_wlan_disconnection(const WiFiEventStationModeDisconnected &event);
+
+void on_mqtt_connection(bool session);
+
+void on_mqtt_disconnection(AsyncMqttClientDisconnectReason reason);
 
-void initial_connection(const char *ssid, const char *psk,
-                        const char *hostname);
-void connect_wlan(Config *config);
-void connect_mqtt(PubSubClient &client, Config *config);
-void disconnect_mqtt(PubSubClient &client, const char *topic);
 size_t construct_json(float *data, char *buffer, int buffer_size);
-void mqtt_transfer(PubSubClient &client, Config *config, float *data);
+
+void mqtt_transfer(float *data);
 
 #endif /* WLAN_H */

platformio.ini

@@ -16,6 +16,6 @@ framework = arduino
 monitor_filters = esp8266_exception_decoder
 lib_deps =
   sensirion/Sensirion I2C SCD4x@^1.1.0
-  knolleary/PubSubClient@^2.8
+  marvinroger/AsyncMqttClient@^0.9.0
   bblanchon/ArduinoJson@^7.4.1
 

src/main.cpp

@@ -1,20 +1,18 @@
-#include "config.h"
 #include "sensor.h"
 #include "wlan.h"
 #include <Arduino.h>
-#include <ESP8266WiFi.h>
-#include <PubSubClient.h>
-#include <stdlib.h>
 
-WiFiClient wifi_client;
-PubSubClient mqtt_client(wifi_client);
 SensirionI2cScd4x sensor;
 
 int error_code;
 char error_msg[64];
+
 const char *config_file_path = "/config.json";
 Config *config;
 
+float data[3];
+unsigned long previous_millis = 0;
+
 void setup() {
     Serial.begin(9600);
     config = (Config *)malloc(sizeof(Config));
@@ -22,15 +20,18 @@ void setup() {
     if (!load_config_file(config_file_path, config))
         Serial.println("ERROR: The config file could not be loaded");
 
-    connect_wlan(config);
-    connect_mqtt(mqtt_client, config);
+    initialize_wlan();
+    initialize_mqtt();
+    connect_wlan();
     initialize_sensor(sensor, error_code, error_msg);
 }
 
 void loop() {
-    float data[3];
+    unsigned long current_millis = millis();
 
+    if (current_millis - previous_millis >= config->sleep_time) {
+        previous_millis = current_millis;
         read_values(sensor, data, error_code, error_msg);
-    mqtt_transfer(mqtt_client, config, data);
-    delay(config->sleep_time);
+        mqtt_transfer(data);
+    }
 }

src/wlan.cpp

@@ -1,48 +1,48 @@
 #include "wlan.h"
-#include <ESP8266WiFi.h>
 
-void initial_connection(const char *ssid, const char *psk,
-                        const char *hostname) {
-    WiFi.hostname(hostname);
-    WiFi.begin(ssid, psk);
-    WiFi.persistent(true);
-    WiFi.setAutoConnect(true);
-    WiFi.setAutoReconnect(true);
+void initialize_wlan() {
+    connection_handler = WiFi.onStationModeGotIP(on_wlan_connection);
+    disconnection_handler =
+        WiFi.onStationModeDisconnected(on_wlan_disconnection);
 }
 
-void connect_wlan(Config *config) {
-    if (WiFi.SSID() != config->ssid)
-        initial_connection(config->ssid, config->psk, config->device_id);
-    while (WiFi.status() != WL_CONNECTED) {
-        delay(1000);
-        Serial.print(".");
+void initialize_mqtt() {
+    mqtt_client.onConnect(on_mqtt_connection);
+    mqtt_client.onDisconnect(on_mqtt_disconnection);
+    mqtt_client.setServer(config->mqtt_host, config->mqtt_port);
+    mqtt_client.setCredentials(config->mqtt_user, config->mqtt_password);
+    Serial.println("MQTT initialization complete");
 }
-    Serial.println("");
+
+void connect_wlan() { WiFi.begin(config->ssid, config->psk); }
+
+void connect_mqtt() {
+    Serial.println("Connecting to MQTT");
+    mqtt_client.connect();
+}
+
+void on_wlan_connection(const WiFiEventStationModeGotIP &event) {
     Serial.println("WiFi connected");
+    connect_mqtt();
 }
 
-void connect_mqtt(PubSubClient &client, Config *config) {
-    bool connection;
-    client.setServer(config->mqtt_host, config->mqtt_port);
+void on_wlan_disconnection(const WiFiEventStationModeDisconnected &event) {
+    Serial.println("WiFi disconnected");
+    mqtt_connection_timer.detach();
+    wlan_connection_timer.once(2, connect_wlan);
+}
 
-    while (!client.connected()) {
-        connection = client.connect(config->device_id, config->mqtt_user,
-                                    config->mqtt_password);
-        if (connection) {
+void on_mqtt_connection(bool session) {
     Serial.println("MQTT connected");
-            client.subscribe(config->topic);
-        } else {
-            Serial.println("MQTT failed to connect");
-            Serial.println(client.state());
-            delay(5000);
-        }
-    }
-}
+    mqtt_client.subscribe(config->topic, 2);
+};
 
-void disconnect_mqtt(PubSubClient &client, const char *topic) {
-    Serial.println("Disconnecting MQTT");
-    client.unsubscribe(topic);
-    client.disconnect();
+void on_mqtt_disconnection(AsyncMqttClientDisconnectReason reason) {
+    Serial.println("MQTT disconnected");
+
+    if (WiFi.isConnected()) {
+        mqtt_connection_timer.once(2, connect_mqtt);
+    }
 }
 
 size_t construct_json(float *data, char *buffer, int buffer_size) {
@@ -54,9 +54,11 @@ size_t construct_json(float *data, char *buffer, int buffer_size) {
     return payload_size;
 }
 
-void mqtt_transfer(PubSubClient &client, Config *config, float *data) {
+void mqtt_transfer(float *data) {
     char buffer[100];
     size_t payload_size = construct_json(data, buffer, 100);
-    client.publish(config->topic, buffer, payload_size);
+    uint16_t response =
+        mqtt_client.publish(config->topic, 2, true, buffer, payload_size);
+    if (response)
         Serial.println("Data transferred successfully");
 }