diff --git a/include/ledmatrix.h b/include/led_matrix.h
similarity index 100%
rename from include/ledmatrix.h
rename to include/led_matrix.h
diff --git a/include/ota_functions.h b/include/ota_functions.h
new file mode 100644
index 0000000..3940b06
--- /dev/null
+++ b/include/ota_functions.h
@@ -0,0 +1,9 @@
+#ifndef OTA_FUNCTIONS_H
+#define OTA_FUNCTIONS_H
+
+#include <Arduino.h>
+
+void handleOTA();
+void setupOTA(String hostname);
+
+#endif /* OTA_FUNCTIONS_H */
diff --git a/include/otafunctions.h b/include/otafunctions.h
deleted file mode 100644
index d0755e7..0000000
--- a/include/otafunctions.h
+++ /dev/null
@@ -1,9 +0,0 @@
-#ifndef OTAFUNCTIONS_H
-#define OTAFUNCTIONS_H
-
-#include <Arduino.h>
-
-void handleOTA();
-void setupOTA(String hostname);
-
-#endif /* OTAFUNCTIONS_H */
diff --git a/include/pong.h b/include/pong.h
index 33710d9..d06f888 100644
--- a/include/pong.h
+++ b/include/pong.h
@@ -15,7 +15,7 @@
 #define PONG_H
 
 #include <Arduino.h>
-#include "ledmatrix.h"
+#include "led_matrix.h"
 #include "udp_logger.h"
 
 #ifdef DEBOUNCE_TIME
diff --git a/include/render_functions.h b/include/render_functions.h
index 64d59a7..154e533 100644
--- a/include/render_functions.h
+++ b/include/render_functions.h
@@ -1,5 +1,5 @@
-#ifndef WORDCLOCK_FUNCTIONS_H
-#define WORDCLOCK_FUNCTIONS_H
+#ifndef RENDER_FUNCTIONS_H
+#define RENDER_FUNCTIONS_H
 
 #include <Arduino.h>
 
@@ -8,4 +8,4 @@ String split(String s, char parser, int index);
 String time_to_string(uint8_t hours, uint8_t minutes);
 void draw_minute_indicator(uint8_t minutes, uint32_t color);
 
-#endif  /* WORDCLOCK_FUNCTIONS_H */
+#endif  /* RENDER_FUNCTIONS_H */
diff --git a/include/snake.h b/include/snake.h
index b6509b8..f8dcd93 100644
--- a/include/snake.h
+++ b/include/snake.h
@@ -14,7 +14,7 @@
 #define snake_h
 
 #include <Arduino.h>
-#include "ledmatrix.h"
+#include "led_matrix.h"
 #include "udp_logger.h"
 
 #ifdef DEBOUNCE_TIME
diff --git a/include/tetris.h b/include/tetris.h
index e6eb595..02e3aaa 100644
--- a/include/tetris.h
+++ b/include/tetris.h
@@ -14,7 +14,7 @@
 #define TETRIS_H
 
 #include <Arduino.h>
-#include "ledmatrix.h"
+#include "led_matrix.h"
 #include "udp_logger.h"
 
 #ifdef DEBOUNCE_TIME
diff --git a/include/wordclock_esp8266.h b/include/wordclock_esp8266.h
index 64f8efd..83228ac 100644
--- a/include/wordclock_esp8266.h
+++ b/include/wordclock_esp8266.h
@@ -3,7 +3,7 @@
 
 #include <Arduino.h>
 #include <ESP8266WebServer.h>
-#include "ledmatrix.h"
+#include "led_matrix.h"
 #include "udp_logger.h"
 
 extern UDPLogger logger;
diff --git a/src/connectivity/otafunctions.cpp b/src/connectivity/ota_functions.cpp
similarity index 98%
rename from src/connectivity/otafunctions.cpp
rename to src/connectivity/ota_functions.cpp
index 10dcda7..18120cd 100644
--- a/src/connectivity/otafunctions.cpp
+++ b/src/connectivity/ota_functions.cpp
@@ -1,6 +1,6 @@
 #include <Arduino.h>
 #include <ArduinoOTA.h>
-#include "otafunctions.h"
+#include "ota_functions.h"
 
 // setup Arduino OTA
 void setupOTA(String hostname)
diff --git a/src/matrix/animation_functions.cpp b/src/matrix/animation_functions.cpp
index afdbd9e..67e9a1c 100644
--- a/src/matrix/animation_functions.cpp
+++ b/src/matrix/animation_functions.cpp
@@ -2,7 +2,7 @@
 #include "animation_functions.h"
 #include "wordclock_constants.h"
 #include "udp_logger.h"
-#include "ledmatrix.h"
+#include "led_matrix.h"
 
 extern UDPLogger logger;
 extern LEDMatrix led_matrix;
diff --git a/src/matrix/ledmatrix.cpp b/src/matrix/led_matrix.cpp
similarity index 98%
rename from src/matrix/ledmatrix.cpp
rename to src/matrix/led_matrix.cpp
index b63c4eb..b882882 100644
--- a/src/matrix/ledmatrix.cpp
+++ b/src/matrix/led_matrix.cpp
@@ -1,4 +1,4 @@
-#include "ledmatrix.h"
+#include "led_matrix.h"
 #include "own_font.h"
 #include "wordclock_constants.h"
 
@@ -21,7 +21,7 @@ const uint32_t colors_24bit[NUM_COLORS] = {
  * @param mybrightness the initial brightness of the leds
  * @param mylogger pointer to the UDPLogger object
  */
-LEDMatrix::LEDMatrix(Adafruit_NeoMatrix * matrix, uint8_t brightness, UDPLogger * logger)
+LEDMatrix::LEDMatrix(Adafruit_NeoMatrix *matrix, uint8_t brightness, UDPLogger *logger)
 {
     _neomatrix = matrix;
     _brightness = brightness;
diff --git a/src/matrix/render_functions.cpp b/src/matrix/render_functions.cpp
index 9e0824a..9c5afef 100644
--- a/src/matrix/render_functions.cpp
+++ b/src/matrix/render_functions.cpp
@@ -1,6 +1,6 @@
 #include <Arduino.h>
 #include "render_functions.h"
-#include "ledmatrix.h"
+#include "led_matrix.h"
 #include "udp_logger.h"
 
 extern LEDMatrix led_matrix;
diff --git a/src/wordclock_esp8266.cpp b/src/wordclock_esp8266.cpp
index f351c4e..4cc254a 100644
--- a/src/wordclock_esp8266.cpp
+++ b/src/wordclock_esp8266.cpp
@@ -37,11 +37,11 @@
 #include "pong.h"
 #include "snake.h"
 #include "tetris.h"
-#include "ledmatrix.h"
+#include "led_matrix.h"
 #include "littlefs_wrapper.h"
 #include "base64_wrapper.h" // copied from https://github.com/Xander-Electronics/Base64
 #include "ntp_client_plus.h"
-#include "otafunctions.h"
+#include "ota_functions.h"
 #include "udp_logger.h"
 #include "wordclock_constants.h"
 #include "render_functions.h"
@@ -323,23 +323,23 @@ void loop()
 
 void update_state_machine()
 {
-    unsigned long current_time = millis();
+    unsigned long current_time_ms = millis();
 
-    if (state_auto_change && (current_time - last_state_change > PERIOD_STATE_CHANGE) && !night_mode)
+    if (state_auto_change && (current_time_ms - last_state_change > PERIOD_STATE_CHANGE) && !night_mode)
     {
         // increment state variable and trigger state change
         state_change((current_state + 1) % NUM_STATES);
         // save last automatic state change
-        last_state_change = current_time;
+        last_state_change = current_time_ms;
     }
 }
 
 void handle_current_state()
 {
-    unsigned long current_time = millis();
+    unsigned long current_time_ms = millis();
 
     // handle mode behaviours (trigger loopCycles of different modes depending on current mode)
-    if (!night_mode && ((current_time - last_step) > PERIODS[state_auto_change][current_state]) && ((current_time - last_led_direct) > TIMEOUT_LEDDIRECT))
+    if (!night_mode && ((current_time_ms - last_step) > PERIODS[state_auto_change][current_state]) && ((current_time_ms - last_led_direct) > TIMEOUT_LEDDIRECT))
     {
         switch (current_state)
         {
@@ -428,13 +428,13 @@ void handle_current_state()
  */
 void update_matrix()
 {
-    unsigned long current_time = millis();
+    unsigned long current_time_ms = millis();
 
     // periodically write colors to matrix
-    if ((current_time - last_animation_step) > PERIOD_MATRIX_UPDATE)
+    if ((current_time_ms - last_animation_step) > PERIOD_MATRIX_UPDATE)
     {
         led_matrix.draw_on_matrix_smooth(filter_factor);
-        last_animation_step = current_time;
+        last_animation_step = current_time_ms;
     }
 }
 
@@ -445,13 +445,15 @@ void update_matrix()
  */
 void send_heartbeat()
 {
-    unsigned long current_time = millis();
+    unsigned long current_time_ms = millis();
 
     // send regularly heartbeat messages via UDP multicast
-    if ((current_time - last_heartbeat) > PERIOD_HEARTBEAT)
+    if ((current_time_ms - last_heartbeat) > PERIOD_HEARTBEAT)
     {
-        logger.log_string("Heartbeat, state: " + state_names[current_state] + ", FreeHeap: " + ESP.getFreeHeap() + ", HeapFrag: " + ESP.getHeapFragmentation() + ", MaxFreeBlock: " + ESP.getMaxFreeBlockSize() + "\nCounter: " + dbg_counter + " , Hours: " + (float)(dbg_counter) / 3600.0 + "\n"); // TODO CHANGE
-        last_heartbeat = current_time;
+        logger.log_string("Heartbeat, state: " + state_names[current_state] + ", FreeHeap: " + ESP.getFreeHeap() + \
+        ", HeapFrag: " + ESP.getHeapFragmentation() + ", MaxFreeBlock: " + ESP.getMaxFreeBlockSize() + "\nCounter: " + \
+        dbg_counter + " , Hours: " + (float)(dbg_counter) / 3600.0 + "\n"); // TODO CHANGE
+        last_heartbeat = current_time_ms;
 
         // Check wifi status (only if no apmode)
         if (WiFi.status() != WL_CONNECTED)
@@ -471,10 +473,10 @@ void send_heartbeat()
  */
 void check_night_mode()
 {
-    unsigned long current_time = millis();
+    unsigned long current_time_ms = millis();
 
     // check if nightmode need to be activated
-    if ((current_time - last_nightmode_check) > PERIOD_NIGHTMODE_CHECK)
+    if ((current_time_ms - last_nightmode_check) > PERIOD_NIGHTMODE_CHECK)
     {
         int hours = ntp_client.getHours24();
         int minutes = ntp_client.getMinutes();
@@ -487,7 +489,7 @@ void check_night_mode()
         {
             set_night_mode(false);
         }
-        last_nightmode_check = current_time;
+        last_nightmode_check = current_time_ms;
     }
 }
 
@@ -498,10 +500,10 @@ void check_night_mode()
  */
 void ntp_time_update()
 {
-    unsigned long current_time = millis();
+    unsigned long current_time_ms = millis();
 
     // NTP time update
-    if ((current_time - last_ntp_update) > PERIOD_NTP_UPDATE)
+    if ((current_time_ms - last_ntp_update) > PERIOD_NTP_UPDATE)
     {
         int ntp_retval = ntp_client.updateNTP();
         switch (ntp_retval)