Transfer the data via MQTT

platformio.ini

@@ -15,5 +15,4 @@ framework = arduino
 lib_deps =
   adafruit/DHT sensor library@^1.4.4
   adafruit/Adafruit Unified Sensor@^1.1.9
-build_type=debug
-monitor_filters = esp8266_exception_decoder
+  knolleary/PubSubClient@^2.8

src/main.cpp

@@ -7,21 +7,35 @@
 DHT dht(DHTPIN, DHTTYPE);
 
 const int fc28_pin = A0;
+// TODO Tweak threshold to get good value
 const int soil_threshold = 40;
+const int num_topics = 3;
+const int max_connection_attempts = 60;
+const char *topics[] = {"homeostasis/temperature", "homeostasis/humidity",
+                        "homeostasis/soil_humidity"};
+const char *device_id = "homeostasis";
+WiFiClient wlan_client;
+PubSubClient mqtt_client(wlan_client);
+
+bool check_valid_value(float value) {
+  return (!isnan(value) && value >= 0 && value <= 100);
+}
 
 void setup() {
   Serial.begin(9600);
   dht.begin();
-  wlan_connection(60);
+  connect_wlan(max_connection_attempts);
 }
 
 void loop() {
+  float temperature = dht.readTemperature();
+  float humidity = dht.readHumidity();
   int analog_val = analogRead(fc28_pin);
   int soil_percentage = map(analog_val, 0, 1023, 0, 100);
-  char buffer[200];
-  sprintf(buffer, "Temperature: %.2f°C Humidity: %.2f%% Soil humidity: %i%%",
-          dht.readTemperature(), dht.readHumidity(), soil_percentage);
-  Serial.println(buffer);
-  delay(30000);
+  float data[] = {temperature, humidity, static_cast<float>(soil_percentage)};
+  if (check_valid_value(temperature) && check_valid_value(humidity)) {
+    mqtt_transfer(mqtt_client, device_id, topics, data, num_topics);
+  }
+  disconnect_mqtt(mqtt_client, topics, num_topics);
   enter_deep_sleep(false);
 }

src/wlan.cpp

@@ -1,6 +1,5 @@
 #include "wlan.h"
 #include "credentials.h"
-#include <ESP8266WiFi.h>
 
 void initial_connection() {
   WiFi.begin(SSID, PSK);
@@ -9,27 +8,52 @@ void initial_connection() {
   WiFi.setAutoReconnect(true);
 }
 
-void wlan_connection(int max_retries) {
+void connect_wlan(const int max_retries) {
   if (WiFi.SSID() != SSID)
     initial_connection();
   int retries = 0;
   while (WiFi.status() != WL_CONNECTED) {
-    retries++;
     if (retries == max_retries)
       enter_deep_sleep(true);
+    retries++;
     delay(1000);
     Serial.print(".");
   }
   Serial.println("WiFi connected");
-  Serial.println(WiFi.localIP());
 }
 
-void mqtt_connection(char *server, int port, char *fingerprint) {
-  WiFiClientSecure client;
-  client.connect(server, port);
+void connect_mqtt(PubSubClient &client, const char *device_id,
+                  const char **topics, int num_topics) {
+  if (!client.connected())
+    client.setServer(MQTT_HOST, MQTT_PORT);
+  if (client.connect(device_id, MQTT_USER, MQTT_PASSWORD)) {
+    Serial.println("MQTT connected");
+    for (int i = 0; i < num_topics; i++)
+      client.subscribe(topics[i]);
+  }
+}
+
+void disconnect_mqtt(PubSubClient &client, const char **topics,
+                     int num_topics) {
+  Serial.println("Disconnecting MQTT");
+  for (int i = 0; i < num_topics; i++)
+    client.unsubscribe(topics[i]);
+  client.disconnect();
+}
+
+void mqtt_transfer(PubSubClient &client, const char *device_id,
+                   const char **topics, float *data, int num_topics) {
+  connect_mqtt(client, device_id, topics, num_topics);
+  for (int i = 0; i < num_topics; i++) {
+    char buffer[50];
+    sprintf(buffer, "%f", data[i]);
+    client.publish(topics[i], buffer);
+  }
+  Serial.println("Data transferred successfully");
 }
 
 void enter_deep_sleep(bool wifi_timeout) {
+  Serial.println("Entering deep sleep");
   if (wifi_timeout)
     WiFi.disconnect();
   ESP.deepSleep(SLEEP_TIME, WAKE_RF_DEFAULT);

src/wlan.h

@@ -1,11 +1,19 @@
 #ifndef WLAN_H
 #define WLAN_H
 
-const int SLEEP_TIME = 480000000;
+#include <ESP8266WiFi.h>
+#include <PubSubClient.h>
+
+const int SLEEP_TIME = 900000000;
 const int WIFI_TIMEOUT = 10000;
 
-void wlan_connection(int max_retries);
-void prometheus_connection(char *server, int port, char *fingerprint);
+void initial_connection();
+void connect_wlan(const int max_retries);
+void connect_mqtt(PubSubClient &client, const char *device_id,
+                  const char **topics, int num_topics);
+void disconnect_mqtt(PubSubClient &client, const char **topics, int num_topics);
+void mqtt_transfer(PubSubClient &client, const char *device_id,
+                   const char **topics, float *data, int num_topics);
 void enter_deep_sleep(bool wifi_timeout);
 
 #endif /* WLAN_H */