diff --git a/lib/Domain/Gun/Gun.cpp b/lib/Domain/Gun/Gun.cpp
index f4672aa..33b4c3c 100644
--- a/lib/Domain/Gun/Gun.cpp
+++ b/lib/Domain/Gun/Gun.cpp
@@ -63,8 +63,9 @@ void Gun::setup(void) {
   updateBatteryDisplayCycleCount = TICKS_BETWEEN_UI_UPDATE;
 
   ui->displaySplash(2000);
-   ui->displayBatteryStatus(hal->getBatteryVoltageMv(),
-                               hal->getBatteryVoltagePercent());
+  
+  // mV is not used
+  ui->displayBatteryStatus(0, hal->getBatteryVoltagePercent());
 
   ui->displayShootCount(0);
 }
\ No newline at end of file
diff --git a/lib/Domain/Gun/Gun.hpp b/lib/Domain/Gun/Gun.hpp
index 48751b0..14831c3 100644
--- a/lib/Domain/Gun/Gun.hpp
+++ b/lib/Domain/Gun/Gun.hpp
@@ -51,6 +51,13 @@ class Gun {
 
   void toggleCalibrationMode() { calibrationMode = !calibrationMode; }
 
+  /**
+   * @brief Gun loop shall be called at least each 10ms,
+   *        but interrupt shall trigger loop() execution in
+   *        a shorter delay.
+   *
+   */
   void loop();
+
   void setup();
 };
\ No newline at end of file
diff --git a/lib/Domain/Gun/IGunUi.hpp b/lib/Domain/Gun/IGunUi.hpp
index 34e0f40..30e500d 100644
--- a/lib/Domain/Gun/IGunUi.hpp
+++ b/lib/Domain/Gun/IGunUi.hpp
@@ -21,6 +21,7 @@
 class IGunUi {
 
 public:
+  virtual void setup() = 0;
   virtual void displaySplash(uint16_t timeoutMs) = 0;
   virtual void displayBatteryStatus(uint16_t mv, uint8_t percent) = 0;
   virtual void displayChargingStatus(bool isCharging) = 0;
diff --git a/lib/Domain/Gun/SSD1306Ui.hpp b/lib/Domain/Gun/SSD1306Ui.hpp
index ed470ac..1de15ca 100644
--- a/lib/Domain/Gun/SSD1306Ui.hpp
+++ b/lib/Domain/Gun/SSD1306Ui.hpp
@@ -36,8 +36,9 @@ static Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
  */
 class SSD1306Ui : public IGunUi {
 public:
-  SSD1306Ui() {
+  SSD1306Ui() {}
 
+  void setup() override{
     if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
       for (;;)
         ; // Don't proceed, loop forever
diff --git a/platformio.ini b/platformio.ini
index 6315620..3998c70 100755
--- a/platformio.ini
+++ b/platformio.ini
@@ -19,7 +19,7 @@ lib_deps =
 #    -cdragon_isp
 #  -cavrispmkII
 
-upload_command = avrdude -vv -b57600 -pm328p -c avrisp -Pcom11 $UPLOAD_FLAGS -U flash:w:$SOURCE:i
+upload_command = avrdude -vv -b57600 -pm328p -c avrisp -Pcom9 $UPLOAD_FLAGS -U flash:w:$SOURCE:i
 
 # upload_protocol=custom
 # upload_speed=115200
diff --git a/src/GunApp.cpp b/src/GunApp.cpp
index 3f2c4ab..3601672 100644
--- a/src/GunApp.cpp
+++ b/src/GunApp.cpp
@@ -53,7 +53,8 @@ void loop(void) {
 }
 
 void setup(void) {
-  hal.setupHeartbeat();
   hal.setGun(&gun);
+  ui.setup();
   gun.setup();
+  hal.setupHeartbeat();
 }
\ No newline at end of file