Use a robust asynchronous MQTT client

README.org

@@ -1,58 +1,44 @@
 * Homeostasis
 
-Temperature and humidity sensor that communicates via MQTT. The project is implemented using a Wemos D1 mini ESP32 board with a DHT22 shield.
+Temperature, air humidity and soil humidity sensor that communicates via MQTT. The project is implemented using a Wemos D1 mini board with the following components:
 
-This specific shield needs to have the data line connected to a pin different to D4, as explained in [[https://blog.zs64.net/2018/02/fixing-the-wemos-d1-mini-dht22-shield][this blog post]].
+- DHT22 temperature and humidity sensor
+- FC-28 soil hygrometer sensor
+- Battery shield
+- 3.7V 1000mAh Lithium battery
+
+The sensor captures the data every 15 minutes and sends it to a MQTT broker and then enters deep sleep, it is important to save power as the device runs off a battery.
 
 #+ATTR_HTML: :width 60%
-[[./board.jpg]]
+[[./result.png]]
 
 ** Pinout of the board
 
 #+ATTR_HTML: :width 40%
 [[./pinout.png]]
-
 ** Dependencies
-
 - [[https://github.com/adafruit/DHT-sensor-library][Adafruit DHT sensor library]]
 - [[https://github.com/adafruit/Adafruit_Sensor][Adafruit Unified Sensor Driver]]
-- [[https://github.com/marvinroger/async-mqtt-client][Async MQTT client]]
+- [[https://github.com/knolleary/pubsubclient][PubSubClient]]
 - [[https://github.com/bblanchon/ArduinoJson][ArduinoJSON]]
-  
-** Configuration
-
-In the data directory, there is a JSON file that allows the configuration of multiple values:
-
-- ssid: WiFi network name
-- psk: WiFi password
-- mqtt_host: IP address of the MQTT broker
-- mqtt_user: username that has write access on the MQTT broker
-- mqtt_password: password for the user that has write access on the MQTT broker
-- mqtt_port: port used by the MQTT broker
-- mqtt_topic: channel name
-- device_id: unique identifier of the sensor
-- sleep_time: time interval between each data transmission
-- connection_attempts: maximum connection attemps to the network
-
-The file needs to be renamed to config.json
-
 ** Deployment
 
-The software uses the Arduino framework and the development environment of [[https://platformio.org/][PlatformIO]], which offers better tooling than the official Arduino IDE.
+The software uses the Arduino framework and the development environment of [[https://platformio.org/][PlatformIO]], which offers better tools than the Arduino IDE.
+
+1. Upload the configuration file to the board:
 
-*** Generate compilation database
-#+begin_src sql
-pio run -t compiledb
-#+end_src
-*** Upload the configuration file to the board
 #+begin_src shell
 pio run -t uploadfs
 #+end_src
-*** Compile the project
+
+2. Compile the project
+
 #+begin_src shell
 pio run -t compile
 #+end_src
-*** Upload firmware
+
+3. Upload firmware
+
 #+begin_src shell
 pio run -t upload
 #+end_src

include/wlan.h

@@ -20,8 +20,6 @@ void connect_mqtt();
 
 void wlan_connection_handler(WiFiEvent_t event);
 
-void on_mqtt_connection(bool session);
-
 void on_mqtt_disconnection(AsyncMqttClientDisconnectReason reason);
 
 size_t construct_json(float *data, char *buffer, int buffer_size);

src/main.cpp

@@ -4,7 +4,7 @@
 #include <Arduino.h>
 #include <DHT.h>
 
-DHT dht(D0, DHT22);
+DHT dht(4, DHT22);
 
 const char *config_file_path = "/config.json";
 Config *config;

src/sensor.cpp

@@ -3,7 +3,11 @@
 void initialize_sensor(DHT &sensor) { sensor.begin(); }
 
 void read_values(DHT &sensor, float *data) {
-    data[0] = sensor.readTemperature();
-    data[1] = sensor.readHumidity();
+    float temperature = sensor.readTemperature();
+    float humidity = sensor.readHumidity();
+
     Serial.println("Data fetched from the sensor");
+
+    data[0] = temperature;
+    data[1] = humidity;
 }

src/wlan.cpp

@@ -3,7 +3,6 @@
 void initialize_wlan() { WiFi.onEvent(wlan_connection_handler); }
 
 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);
@@ -32,8 +31,6 @@ void wlan_connection_handler(WiFiEvent_t event) {
     }
 }
 
-void on_mqtt_connection(bool session) { Serial.println("MQTT connected"); }
-
 void on_mqtt_disconnection(AsyncMqttClientDisconnectReason reason) {
     Serial.println("MQTT disconnected");