diff --git a/lib/Cross/Gun/SSD1306Ui.hpp b/lib/Cross/Gun/SSD1306Ui.hpp
index e0d1b1d..7920620 100644
--- a/lib/Cross/Gun/SSD1306Ui.hpp
+++ b/lib/Cross/Gun/SSD1306Ui.hpp
@@ -33,6 +33,7 @@ static Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
 /**
  * @brief UI on a SSD1306 OLED display wired over I²C bus
  *
+ * Used https://rickkas7.github.io/DisplayGenerator/index.html for prototyping
  */
 class SSD1306Ui : public IGunUi {
 public:
@@ -57,46 +58,49 @@ class SSD1306Ui : public IGunUi {
     display.display();
     delay(timeoutMs);
     display.clearDisplay();
+    display.display();
   }
 
   void displayBatteryStatus(uint16_t mv, uint8_t percent) override {
     display.setFont(NULL);
-    display.fillRect(79, 0, 59, 24, 0); // clear
+    display.fillRect(100, 0, 25, 9, 0); // clear
     display.setCursor(100, 2);
     display.print(percent);
     display.println("%");
-
-    // prepare font for next shoot count display
-    display.setFont(&FreeMonoBold18pt7b);
   }
+
   void displayChargingStatus(bool isCharging) override {
-    display.setCursor(80, 15);
     if (isCharging) {
+      display.setFont(NULL);
+      display.setCursor(80, 15);
       display.println("charging");
     } else {
-      display.println("        ");
+      display.fillRect(80, 12, 47, 11, 0); // clear
     }
   }
 
   void displayShootCount(uint16_t count) override {
     display.fillRect(11, 0, 68, 30, 0); // clear
-
-    if (count > 999)
+    display.setFont(&FreeMonoBold18pt7b);
+    if (count > 999) {
       count = 0;
-
+    }
     if (count < 10) {
       display.setCursor(15, 25);
     } else {
       display.setCursor(10, 25);
     }
-    display.setFont(&FreeMonoBold18pt7b);
     display.print(count);
     display.display();
   }
 
+  void clearCalibration() override {
+    display.fillRect(2, 10, 126, 14, 0); // clear
+  }
+
   void displayCalibration() override {
-    display.fillRect(11, 0, 68, 30, 0); // clear
-    display.setCursor(15, 25);
+    display.clearDisplay();
+    display.setCursor(2, 25);
     display.setFont(&FreeMonoOblique9pt7b);
     display.print("Calibration");
     display.display();
diff --git a/lib/Domain/Gun/Button.cpp b/lib/Domain/Gun/Button.cpp
index c113686..6db3ad7 100644
--- a/lib/Domain/Gun/Button.cpp
+++ b/lib/Domain/Gun/Button.cpp
@@ -18,5 +18,5 @@
 #include <Gun/Gun.hpp>
 
 void Button::setGun(Gun *gun) { this->gun = gun; }
-void Button::onShortPress() { gun->shootCount = 0; }
+void Button::onShortPress() { gun->resetShoots(); }
 void Button::onLongPress() { gun->toggleCalibrationMode(); }
\ No newline at end of file
diff --git a/lib/Domain/Gun/Gun.cpp b/lib/Domain/Gun/Gun.cpp
index e258046..a9ff4b7 100644
--- a/lib/Domain/Gun/Gun.cpp
+++ b/lib/Domain/Gun/Gun.cpp
@@ -40,12 +40,19 @@ void Gun::toggleCalibrationMode() {
     ui->displayCalibration();
   } else {
     hal->laserOff();
+    ui->clearCalibration();
     ui->displayShootCount(shootCount);
+    batteryDisplayCycleCountdown = 0;
   }
 }
 
+void Gun::resetShoots() {
+  shootCount = 0;
+  ui->displayShootCount(shootCount);
+}
+
 void Gun::activateShoot() {
-  if (shootCycleCountdown == 0) {
+  if (!calibrationMode && shootCycleCountdown == 0) {
     shootCount += 1;
     hal->laserOn();
     hal->vibrationOn();
@@ -74,6 +81,7 @@ void Gun::loop(void) {
       shootCycleCountdown--;
     }
   }
+
   if (batteryDisplayCycleCountdown > 0) {
     batteryDisplayCycleCountdown--;
   } else {
@@ -81,7 +89,6 @@ void Gun::loop(void) {
                              hal->getBatteryVoltagePercent());
     batteryDisplayCycleCountdown = TICKS_BETWEEN_BATTERY_UI_UPDATE;
   }
-  hal->sleep();
 }
 
 void Gun::setup(void) {
diff --git a/lib/Domain/Gun/Gun.hpp b/lib/Domain/Gun/Gun.hpp
index b0ff0df..cf1fda3 100644
--- a/lib/Domain/Gun/Gun.hpp
+++ b/lib/Domain/Gun/Gun.hpp
@@ -41,6 +41,14 @@ class Gun {
 
   Gun(IGunHal *hal, IGunUi *ui);
 
+  /**
+   * Reset shoot count and redisplay
+   */
+  void resetShoots();
+
+  /**
+   * Activate laser and vibrator
+   */
   void activateShoot();
 
   void toggleCalibrationMode();
diff --git a/lib/Domain/Gun/IGunUi.hpp b/lib/Domain/Gun/IGunUi.hpp
index c66510a..3f4a60e 100644
--- a/lib/Domain/Gun/IGunUi.hpp
+++ b/lib/Domain/Gun/IGunUi.hpp
@@ -27,4 +27,5 @@ class IGunUi {
   virtual void displayChargingStatus(bool isCharging) = 0;
   virtual void displayShootCount(uint16_t shootCount) = 0;
   virtual void displayCalibration() = 0;
+  virtual void clearCalibration() = 0;
 };
\ No newline at end of file
diff --git a/src/GunApp.cpp b/src/GunApp.cpp
index 1e75f03..fa32e66 100644
--- a/src/GunApp.cpp
+++ b/src/GunApp.cpp
@@ -28,24 +28,32 @@ ISR(TIMER2_COMPA_vect) { tick = true; }
 
 volatile Contactor::Event pendingTriggerEvent;
 void triggerInterruptHandler() {
-  if (bit_is_set(PIND, PD2)) {
+  if (hal.triggerIsUp()) {
     pendingTriggerEvent = Contactor::Event::Released;
   } else {
     pendingTriggerEvent = Contactor::Event::Pressed;
   }
+  tick = true;
 }
 
 volatile Contactor::Event pendingButtonEvent;
 void buttonInterruptHandler() {
-  if (bit_is_set(PIND, PD3)) {
+  if (hal.buttonIsUp()) {
     pendingButtonEvent = Contactor::Event::Released;
   } else {
     pendingButtonEvent = Contactor::Event::Pressed;
   }
+  tick = true;
 }
 
 void loop(void) {
 
+  // other interrupt may wakeup the board
+  // and trigger loop(). Especially counter0
+  // and counter1, used internally by the Arduino
+  // framework. Avoid processing these wakeups as
+  // applicative events using 'tick' control variable.
+  
   if (tick) {
     // wire interrupt-based events with main code
     gun.trigger.pendingEvent = pendingTriggerEvent;
@@ -55,6 +63,7 @@ void loop(void) {
 
     gun.loop();
     tick = false;
+    hal.sleep();
   }
 }
 
@@ -62,5 +71,6 @@ void setup(void) {
   hal.setGun(&gun);
   ui.setup();
   gun.setup();
+  hal.configureInputCallbacks();
   hal.setupHeartbeat();
 }
\ No newline at end of file
diff --git a/test/native/test_gun/gun.cpp b/test/native/test_gun/gun.cpp
index 6b98ea7..63fa00d 100644
--- a/test/native/test_gun/gun.cpp
+++ b/test/native/test_gun/gun.cpp
@@ -37,6 +37,7 @@ using namespace fakeit;
   When(Method(mockUi, displayBatteryStatus)).AlwaysReturn();                   \
   When(Method(mockUi, displayShootCount)).AlwaysReturn();                      \
   When(Method(mockUi, displayCalibration)).AlwaysReturn();                     \
+  When(Method(mockUi, clearCalibration)).AlwaysReturn();                       \
   When(Method(mockUi, displaySplash)).AlwaysReturn();
 
 void tearDown() {}
@@ -85,8 +86,8 @@ void expect_gun_to_shoot_50ms_on_trigger_down() {
   Verify(Method(mockHal, vibrationOn)).Once();
   Verify(Method(mockHal, vibrationOff)).Once();
   Verify(Method(mockHal, laserOff)).Once();
-  Verify(Method(mockHal, sleep)).Exactly(7);
 }
+
 void expect_ui_to_display_battery_state_at_boot_and_each_1s() {
   Mock<IGunUi> mockUi;
   Mock<IGunHal> mockHal;
@@ -137,15 +138,67 @@ void expect_switch_to_maintenance_after_2s_button_continuous_press() {
 
   // back to normal
   Verify(Method(mockHal, laserOff)).Exactly(1);
+  Verify(Method(mockUi, clearCalibration)).Exactly(1);
   Verify(Method(mockUi, displayShootCount)).Exactly(1);
 }
 
+void expect_button_press_to_reset_shoot_count_and_redisplay() {
+  Mock<IGunUi> mockUi;
+  Mock<IGunHal> mockHal;
+  MOCK_ALL();
+  IGunUi &ui = mockUi.get();
+  IGunHal &hal = mockHal.get();
+
+  Gun gun(&hal, &ui);
+
+  gun.shootCount = 10;
+
+  gun.button.pendingEvent = Contactor::Event::Pressed;
+  gun.loop();
+  gun.button.pendingEvent = Contactor::Event::Released;
+  gun.loop();
+
+  TEST_ASSERT_EQUAL_MESSAGE(0, gun.shootCount, "Shoot count shall be reset");
+  Verify(Method(mockUi, displayShootCount)).Exactly(1);
+}
+
+void expect_trigger_to_have_no_effect_in_calibration_mode() {
+  Mock<IGunUi> mockUi;
+  Mock<IGunHal> mockHal;
+
+  MOCK_ALL();
+
+  IGunUi &ui = mockUi.get();
+  IGunHal &hal = mockHal.get();
+
+  Gun gun(&hal, &ui);
+
+  gun.button.pendingEvent = Contactor::Event::Pressed;
+  for (uint8_t tickCounter = 0; tickCounter <= 200; tickCounter++) {
+    // long press shall be accounted after 2s, 200 ticks
+    gun.loop();
+  }
+
+  gun.button.pendingEvent = Contactor::Event::Released;
+  gun.loop();
+
+  gun.trigger.pendingEvent = Contactor::Event::Pressed;
+  gun.loop();
+  gun.trigger.pendingEvent = Contactor::Event::Released;
+  gun.loop();
+
+  Verify(Method(mockHal, laserOn)).Exactly(1);
+  Verify(Method(mockHal, laserOff)).Exactly(0);
+}
+
 int main(int, char **) {
   UNITY_BEGIN();
   RUN_TEST(expect_gun_to_loop);
   RUN_TEST(expect_gun_to_shoot_50ms_on_trigger_down);
   RUN_TEST(expect_ui_to_display_battery_state_at_boot_and_each_1s);
   RUN_TEST(expect_switch_to_maintenance_after_2s_button_continuous_press);
+  RUN_TEST(expect_button_press_to_reset_shoot_count_and_redisplay);
+  RUN_TEST(expect_trigger_to_have_no_effect_in_calibration_mode);
 
   UNITY_END();
   return 0;