Implement WLAN connection and deep sleep

.gitignore

@@ -1 +1,2 @@
 .pio
+src/credentials.h

src/main.cpp

@@ -1,3 +1,4 @@
+#include "wlan.h"
 #include <Arduino.h>
 #include <DHT.h>
 
@@ -12,14 +13,17 @@ int soil_threshold = 40;
 void setup() {
   Serial.begin(9600);
   dht.begin();
+  wlan_connection();
 }
 
 void loop() {
-  char buffer[200];
+  unsigned long start_time = millis();
   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);
+  enter_deep_sleep(start_time);
 }

src/wlan.cpp

@@ -0,0 +1,31 @@
+#include "wlan.h"
+#include "credentials.h"
+#include <ESP8266WiFi.h>
+
+void wlan_connection() {
+  if (WiFi.SSID() != SSID) {
+    WiFi.begin(SSID, PSK);
+    WiFi.persistent(true);
+    WiFi.setAutoConnect(true);
+    WiFi.setAutoReconnect(true);
+  }
+  while (WiFi.status() != WL_CONNECTED) {
+    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 enter_deep_sleep(const int start_time) {
+  int elapsed = millis() - start_time;
+  if (elapsed >= WIFI_TIMEOUT) {
+    WiFi.disconnect();
+  }
+  ESP.deepSleep(SLEEP_TIME, WAKE_RF_DEFAULT);
+}

src/wlan.h

@@ -0,0 +1,11 @@
+#ifndef WLAN_H
+#define WLAN_H
+
+const int SLEEP_TIME = 480000000;
+const int WIFI_TIMEOUT = 10000;
+
+void wlan_connection();
+void prometheus_connection(char *server, int port, char *fingerprint);
+void enter_deep_sleep(const int start_time);
+
+#endif /* WLAN_H */