switch to PA0 as BTN

CMakeLists.txt

@@ -12,8 +12,8 @@ set(CMAKE_SYSTEM_NAME Generic)
 set(CMAKE_C_COMPILER avr-gcc)
 set(OBJCOPY avr-objcopy)
 
-# Compiler flags
-set(CMAKE_C_FLAGS "-mmcu=${MCU} -DF_CPU=${F_CPU} -Os -Wall")
+# Compiler flags: optimize, warnings, treat warnings as errors
+set(CMAKE_C_FLAGS "-mmcu=${MCU} -DF_CPU=${F_CPU} -Os -Wall -Werror")
 
 # Sources
 add_executable(main.elf main.c)

main.c

@@ -12,11 +12,12 @@
 /** @defgroup LED_Masks LED bitmasks for PORTA
  *  @{
  */
-#define PA1_SET_MASK 0x02 ///< LED 1–2
-#define PA2_SET_MASK 0x04 ///< LED 3–6
-#define PA3_SET_MASK 0x08 ///< LED 7–8
-#define PA6_SET_MASK 0x40 ///< Switch input (was green LED pin) TODO: Switch to PA0
-#define PA7_SET_MASK 0x80 ///< Red LED
+#define BUTTON_PIN_MASK 0x01 // PA0
+#define PA1_SET_MASK 0x02    ///< LED 1–2
+#define PA2_SET_MASK 0x04    ///< LED 3–6
+#define PA3_SET_MASK 0x08    ///< LED 7–8
+#define PA6_SET_MASK 0x40    ///< Green LED pin
+#define PA7_SET_MASK 0x80    ///< Red LED
 /** @} */
 
 #define MAIN_LOOP_SLEEP 10U                 // Main loop delay in ms (system tick)
@@ -50,9 +51,9 @@ int main(void)
                   /*PA6_SET_MASK |*/ // PA6 now input (switch)
                   PA7_SET_MASK);
 
-    // Configure PA6 as input with pull-up TODO: Switch to PA0
-    VPORTA.DIR &= ~PA6_SET_MASK;       // Input
-    PORTA.PIN6CTRL = PORT_PULLUPEN_bm; // Pull-up enabled
+    // Configure PA0 as input with pull-up
+    VPORTA.DIR &= ~BUTTON_PIN_MASK;    // Input
+    PORTA.PIN0CTRL = PORT_PULLUPEN_bm; // Pull-up enabled
 
     // --- ensure all LEDs off at startup ---
     leds_off();
@@ -128,7 +129,7 @@ static void handleSwitch(void)
     static uint16_t pressTicks = 0;  ///< press duration counter
     static bool prevPressed = false; ///< previous switch state
 
-    bool pressed = !(VPORTA.IN & PA6_SET_MASK); // active-low
+    bool pressed = !(VPORTA.IN & BUTTON_PIN_MASK); // active-low
 
     if (pressed)
     {