Replace the MQTT client with a robust async option

.clangd

@@ -0,0 +1,26 @@
+CompileFlags:
+  Add: [
+    -DSSIZE_MAX,
+    -DLWIP_NO_UNISTD_H=1,
+    -Dssize_t=long,
+    -D_SSIZE_T_DECLARED,
+    -Wno-unknown-warning-option
+  ]
+  Remove: [
+    -mlong-calls,
+    -fno-tree-switch-conversion,
+    -mtext-section-literals,
+    -mlongcalls,
+    -fstrict-volatile-bitfields,
+    -free,
+    -fipa-pta,
+    -march=*,
+    -mabi=*,
+    -mcpu=*
+  ]
+Diagnostics:
+  Suppress:
+    - pp_including_mainfile_in_preamble
+    - pp_expr_bad_token_start_expr
+    - redefinition_different_typedef
+    - main_returns_nonint

README.org

@@ -1,12 +1,6 @@
 * Muraqib
 
-Temperature and humidity sensor that sends its data via MQTT. The project is implemented using a Wemos D1 mini board with the following components:
-
-- DHT22 temperature and humidity sensor
-- Battery shield
-- 3.7V 1000mAh Lithium battery
-
-The sensor captures the data every 5 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. This sensor is part of a project to grow mushrooms in a controlled environment.
+CO2 sensor that collects and sends its data via MQTT to a server. The board of the sensor is the Wemos D1 mini and the sensor is a SCD41.
 
 ** Pinout of the board
 
@@ -14,8 +8,7 @@ The sensor captures the data every 5 minutes and sends it to a MQTT broker and t
 [[./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/Sensirion/arduino-i2c-scd4x][Sensirion I²C SCD4X Arduino Library]]
 - [[https://github.com/knolleary/pubsubclient][PubSubClient]]
 - [[https://github.com/bblanchon/ArduinoJson][ArduinoJSON]]
 ** Configuration

data/example.json

@@ -7,6 +7,5 @@
   "mqtt_port": 1883,
   "mqtt_topic": "",
   "device_id": "",
-  "sleep_time": 30,
-  "connection_attempts": 60
+  "sleep_time": 30
 }

include/config.h

@@ -1,8 +1,6 @@
 #ifndef CONFIG_H_
 #define CONFIG_H_
 
-#include "FS.h"
-#include "LittleFS.h"
 #include <ArduinoJson.h>
 
 typedef struct {
@@ -14,14 +12,13 @@ typedef struct {
     const char *topic;
     const char *device_id;
     int mqtt_port;
-  long sleep_time;
-  int connection_attempts;
+    unsigned long sleep_time;
 } Config;
 
 void initialize_config(Config *config, JsonDocument json);
 
 bool load_config_file(const char *file_path, Config *config);
 
-long minutes_to_microseconds(int minutes);
+long minutes_to_milliseconds(int minutes);
 
 #endif // CONFIG_H_

include/sensor.h

@@ -0,0 +1,14 @@
+#ifndef SENSOR_H_
+#define SENSOR_H_
+
+#include <SensirionI2cScd4x.h>
+
+void handle_error(int code, char *msg);
+
+void initialize_sensor(SensirionI2cScd4x &sensor, int error_code,
+                       char *error_msg);
+
+void read_values(SensirionI2cScd4x &sensor, float *data, int error_code,
+                 char *error_msg);
+
+#endif // SENSOR_H_

include/wlan.h

@@ -2,15 +2,33 @@
 #define WLAN_H
 
 #include "config.h"
+#include <AsyncMqttClient.h>
 #include <ESP8266WiFi.h>
-#include <PubSubClient.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

@@ -13,8 +13,9 @@ platform = espressif8266
 board = d1_mini
 board_build.filesystem = littlefs
 framework = arduino
+monitor_filters = esp8266_exception_decoder
 lib_deps =
-  adafruit/DHT sensor library@^1.4.6
-  adafruit/Adafruit Unified Sensor@^1.1.15
-  knolleary/PubSubClient@^2.8
+  sensirion/Sensirion I2C SCD4x@^1.1.0
+  marvinroger/AsyncMqttClient@^0.9.0
   bblanchon/ArduinoJson@^7.4.1
+

src/config.cpp

@@ -1,4 +1,5 @@
 #include "config.h"
+#include "LittleFS.h"
 
 void initialize_config(Config *config, JsonDocument json) {
     config->ssid = strdup(json["ssid"]);
@@ -9,8 +10,7 @@ void initialize_config(Config *config, JsonDocument json) {
     config->topic = strdup(json["mqtt_topic"]);
     config->device_id = strdup(json["device_id"]);
     config->mqtt_port = json["mqtt_port"];
-  config->sleep_time = minutes_to_microseconds(json["sleep_time"]);
-  config->connection_attempts = json["connection_attempts"];
+    config->sleep_time = minutes_to_milliseconds(json["sleep_time"]);
 }
 
 bool load_config_file(const char *file_path, Config *config) {
@@ -27,4 +27,4 @@ bool load_config_file(const char *file_path, Config *config) {
     return true;
 }
 
-long minutes_to_microseconds(int minutes) { return (minutes * 6e7); }
+long minutes_to_milliseconds(int minutes) { return (minutes * 6e4); }

src/main.cpp

@@ -1,38 +1,37 @@
-#include "config.h"
+#include "sensor.h"
 #include "wlan.h"
 #include <Arduino.h>
-#include <DHT.h>
 
-#define DHTTYPE DHT22
-#define DHTPIN 4
-DHT dht(DHTPIN, DHTTYPE);
+SensirionI2cScd4x sensor;
+
+int error_code;
+char error_msg[64];
 
 const char *config_file_path = "/config.json";
 Config *config;
-WiFiClient wifi_client;
-PubSubClient mqtt_client(wifi_client);
 
-bool check_valid_value(float value) {
-  return (!isnan(value) && value >= 0 && value <= 100);
-}
+float data[3];
+unsigned long previous_millis = 0;
 
 void setup() {
     Serial.begin(9600);
-  dht.begin();
     config = (Config *)malloc(sizeof(Config));
+
     if (!load_config_file(config_file_path, config))
         Serial.println("ERROR: The config file could not be loaded");
-  connect_wlan(config);
+
+    initialize_wlan();
+    initialize_mqtt();
+    connect_wlan();
+    initialize_sensor(sensor, error_code, error_msg);
 }
 
 void loop() {
-  float temperature = dht.readTemperature();
-  float humidity = dht.readHumidity();
-  float data[2] = {temperature, humidity};
-  if (check_valid_value(temperature) && check_valid_value(humidity)) {
-    mqtt_transfer(mqtt_client, config, data);
+    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(data);
     }
-  disconnect_mqtt(mqtt_client, config->topic);
-  free(config);
-  enter_deep_sleep(false, config->sleep_time);
 }

src/sensor.cpp

@@ -0,0 +1,49 @@
+#include "sensor.h"
+#include <Wire.h>
+
+// TODO Trigger a reset when an error occurs
+void handle_error(int code, char *msg) {
+    if (code) {
+        errorToString(code, msg, sizeof msg);
+        exit(1);
+    }
+}
+
+void initialize_sensor(SensirionI2cScd4x &sensor, int error_code,
+                       char *error_msg) {
+    Wire.begin();
+    sensor.begin(Wire, SCD41_I2C_ADDR_62);
+    Serial.println("Starting sensor initialization");
+
+    error_code = sensor.wakeUp();
+    handle_error(error_code, error_msg);
+    error_code = sensor.stopPeriodicMeasurement();
+    handle_error(error_code, error_msg);
+    error_code = sensor.reinit();
+    handle_error(error_code, error_msg);
+    error_code = sensor.startPeriodicMeasurement();
+    handle_error(error_code, error_msg);
+
+    Serial.println("The sensor was initialized properly");
+};
+
+void read_values(SensirionI2cScd4x &sensor, float *data, int error_code,
+                 char *error_msg) {
+    bool data_available = false;
+    short unsigned int co2_concentration = 0.0;
+
+    error_code = sensor.getDataReadyStatus(data_available);
+    handle_error(error_code, error_msg);
+
+    while (!data_available) {
+        delay(100);
+        error_code = sensor.getDataReadyStatus(data_available);
+        handle_error(error_code, error_msg);
+    }
+
+    Serial.println("Data fetched from the sensor");
+
+    error_code = sensor.readMeasurement(co2_concentration, data[1], data[2]);
+    data[0] = co2_concentration;
+    handle_error(error_code, error_msg);
+}

src/wlan.cpp

@@ -1,53 +1,64 @@
 #include "wlan.h"
-#include <ArduinoJson.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");
 }
+
+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) {
-  if (!client.connected())
-    client.setServer(config->mqtt_host, config->mqtt_port);
-  if (client.connect(config->device_id, config->mqtt_user,
-                     config->mqtt_password)) {
+void on_wlan_disconnection(const WiFiEventStationModeDisconnected &event) {
+    Serial.println("WiFi disconnected");
+    mqtt_connection_timer.detach();
+    wlan_connection_timer.once(2, connect_wlan);
+}
+
+void on_mqtt_connection(bool session) {
     Serial.println("MQTT connected");
-    client.subscribe(config->topic);
-  }
-}
+    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) {
     JsonDocument json;
-  json["temperature"] = data[0];
-  json["humidity"] = data[1];
+    json["co2_concentration"] = data[0];
+    json["temperature"] = data[1];
+    json["humidity"] = data[2];
     size_t payload_size = serializeJson(json, buffer, buffer_size);
     return payload_size;
 }
 
-void mqtt_transfer(PubSubClient &client, Config *config, float *data) {
+void mqtt_transfer(float *data) {
     char buffer[100];
-  connect_mqtt(client, config);
     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");
 }