add mqtt module

domestic-climate-monitor/main/CMakeLists.txt

@@ -1,2 +1,2 @@
-idf_component_register(SRCS "main.c" "wifi.c"
+idf_component_register(SRCS "main.c" "wifi.c" "mqtt.c"
                     INCLUDE_DIRS ".")

domestic-climate-monitor/main/main.c

@@ -4,23 +4,25 @@
 #include "freertos/task.h"
 #include "nvs_flash.h"
 
+#include "mqtt.h"
+#include "mqtt_client.h"
 #include "wifi.h"
 
 static const char *TAG = "main";
-void setup(void) {
-  ESP_ERROR_CHECK(nvs_flash_init());
-  wifi_connect();
-}
 
-void loop(void) {
+void loop(esp_mqtt_client_handle_t mqtt_client)
+{
   ESP_LOGI(TAG, "Loop running...");
+  mqtt_publish(mqtt_client, "Test message");
   vTaskDelay(pdMS_TO_TICKS(1000));
 }
 
-void app_main(void) {
-  setup();
-
+void app_main(void)
+{
+  ESP_ERROR_CHECK(nvs_flash_init());
+  wifi_connect();
+  esp_mqtt_client_handle_t mqtt_client = mqtt_connect();
   while (1) {
-    loop();
+    loop(mqtt_client);
   }
 }

domestic-climate-monitor/main/mqtt.c

@@ -0,0 +1,69 @@
+#include "esp_event_base.h"
+#include "esp_log.h"
+#include "mqtt_client.h"
+
+#include <stdint.h>
+#include <string.h>
+
+static const char *TAG = "mqtt"; // Logs are coming from this mqtt module
+
+static uint32_t MQTT_CONNECTED = 0;
+static int s_retry_num = 0;
+
+#define MQTT_TOPIC "/topic/test"
+#define MQTT_BROKER "mqtt://192.168.178.53:1883"
+#define MAX_RETRY 5
+
+esp_mqtt_client_handle_t mqtt_connect();
+
+static void mqtt_event_handler(void *handler_args, esp_event_base_t base,
+                               int32_t event_id, void *event_data)
+{
+  if (event_id == MQTT_EVENT_CONNECTED) {
+    ESP_LOGI(TAG, "Connected to MQTT broker.");
+    MQTT_CONNECTED = 1;
+  }
+
+  if (event_id == MQTT_EVENT_PUBLISHED) {
+    // Cast event which is void to a specific type provided by ESP-IDF
+    // Then dereference and get `msg_id` field
+    esp_mqtt_event_handle_t event = (esp_mqtt_event_handle_t)event_data;
+    ESP_LOGI(TAG, "Message published succesfully, msg_id: %d", (*event).msg_id);
+  }
+
+  if (event_id == MQTT_EVENT_DISCONNECTED) {
+    MQTT_CONNECTED = 0;
+    ESP_LOGI(TAG, "Disconnected from MQTT broker. Attempting to reconnect.");
+    if (s_retry_num < MAX_RETRY) {
+      mqtt_connect();
+      s_retry_num++;
+      ESP_LOGI(TAG, "Retrying MQTT connection.");
+    } else {
+      ESP_LOGI(TAG, "Could not connect to MQTT broker. Giving up.");
+    }
+  }
+}
+
+esp_mqtt_client_handle_t mqtt_connect()
+{
+  ESP_LOGI(TAG, "Attempting to connect to MQTT broker %s", MQTT_BROKER);
+  esp_mqtt_client_config_t mqtt_config = {.broker.address.uri = MQTT_BROKER};
+  esp_mqtt_client_handle_t client = esp_mqtt_client_init(&mqtt_config);
+  esp_mqtt_client_register_event(client, ESP_EVENT_ANY_ID, mqtt_event_handler,
+                                 client);
+  esp_mqtt_client_start(client);
+  return client;
+}
+
+void mqtt_publish(esp_mqtt_client_handle_t client, const char *payload)
+{
+  if (MQTT_CONNECTED) {
+    ESP_LOGI(TAG, "Publishing payload %s to topic %s", payload, MQTT_TOPIC);
+    esp_mqtt_client_publish(client, MQTT_TOPIC, payload, strlen(payload), 0, 0);
+  } else {
+    ESP_LOGI(TAG, "Could not publish to MQTT topic %s. Not connected to broker",
+             MQTT_TOPIC);
+  }
+}
+
+// https://github.com/ESP32Tutorials/esp32-mqtt-pub-sub-esp-idf/blob/main/main/app_main.c

domestic-climate-monitor/main/mqtt.h

@@ -0,0 +1,8 @@
+#ifndef MQTT_H
+#define MQTT_H
+
+#include "mqtt_client.h"
+esp_mqtt_client_handle_t mqtt_connect();
+void mqtt_publish(esp_mqtt_client_handle_t client, const char *payload);
+
+#endif // MQTT_H