implement no blocking blink

main.c

@@ -1,42 +1,215 @@
+/**
+ * @file main.c
+ * @brief Bike rear light implementation for ATTINY202.
+ *
+ */
+
+#include <stdint.h>
+#include <stdbool.h>
 #include <avr/io.h>
 #include <util/delay.h>
 
-#define PA1_SET_MASK 0x02 // LED 1 to 2
+/** @defgroup LED_Masks LED bitmasks for PORTA
-#define PA2_SET_MASK 0x04 // LED 3 to 6
+ *  @{
-#define PA3_SET_MASK 0x08 // LED 7 to 8
+ */
-#define PA6_SET_MASK 0x40 // Green LED
+#define PA1_SET_MASK 0x02 ///< LED 1–2
-#define PA7_SET_MASK 0x80 // Red LED
+#define PA2_SET_MASK 0x04 ///< LED 3–6
+#define PA3_SET_MASK 0x08 ///< LED 7–8
+#define PA6_SET_MASK 0x40 ///< Green LED
+#define PA7_SET_MASK 0x80 ///< Red LED
+/** @} */
 
+/** @brief Main loop delay in ms (system tick). */
+#define MAIN_LOOP_SLEEP 10U
+
+/** @brief Convert milliseconds to system ticks (integer division). */
+#define MS_TO_TICKS(ms) ((ms) / MAIN_LOOP_SLEEP)
+
+/** @brief Global flag: enable or disable LED output. */
+volatile bool bLedEnabled = true;
+
+// Function forward declarations
+void blinkLed(void);
+static inline void leds_off(void);
+
+/**
+ * @brief Main entry point.
+ *
+ * Initializes I/O ports and runs the main loop, periodically calling @ref blinkLed().
+ *
+ * @return never returns
+ */
 int main(void)
 {
-    VPORTA.DIR = 0x0;
+    // --- configure LED pins as outputs ---
+    VPORTA.DIR = (PA1_SET_MASK | PA2_SET_MASK | PA3_SET_MASK |
+                  PA6_SET_MASK | PA7_SET_MASK);
 
-    // Configure PA1 as output (Pin 4 on ATTINY202-SSN)
+    // --- ensure all LEDs off at startup ---
-    VPORTA.DIR |= PA1_SET_MASK;
+    leds_off();
+    VPORTA.OUT &= (uint8_t)~(PA6_SET_MASK | PA7_SET_MASK);
 
-    // Configure PA2 as output (Pin 5 on ATTINY202-SSN)
+    while (true)
-    VPORTA.DIR |= PA2_SET_MASK;
-
-    // Configure PA3 as output (Pin 7 on ATTINY202-SSN)
-    VPORTA.DIR |= PA3_SET_MASK;
-
-    // Configure PA6 as output (Pin 2 on ATTINY202-SSN)
-    VPORTA.DIR |= PA6_SET_MASK;
-
-    // Configure PA7 as output (Pin 3 on ATTINY202-SSN)
-    VPORTA.DIR |= PA7_SET_MASK;
-
-    VPORTA.OUT ^= !PA1_SET_MASK; // LED 1 to 2
-    VPORTA.OUT ^= !PA2_SET_MASK; // LED 3 to 6
-    VPORTA.OUT ^= !PA3_SET_MASK; // LED 7 to 8
-
-    while (1)
     {
-        VPORTA.OUT ^= PA6_SET_MASK; // toggle green LED
+        // TODO: add status LED handling if needed
-        VPORTA.OUT ^= PA7_SET_MASK; // toggle red LED
+        // VPORTA.OUT ^= PA6_SET_MASK; // toggle green LED
+        // VPORTA.OUT ^= PA7_SET_MASK; // toggle red LED
 
-        VPORTA.OUT ^= PA2_SET_MASK; // toggle inner four LED
+        blinkLed();
 
-        _delay_ms(500);
+        _delay_ms(MAIN_LOOP_SLEEP);
+    }
+}
+
+/**
+ * @brief Switch off all controlled LEDs (PA1, PA2, PA3).
+ *
+ * @note Declared inline for speed (single instruction sequence).
+ */
+static inline void leds_off(void)
+{
+    VPORTA.OUT &= (uint8_t)~(PA1_SET_MASK | PA2_SET_MASK | PA3_SET_MASK);
+}
+
+/**
+ * @brief LED blink state machine.
+ *
+ * Implements the following repeating sequence (non-blocking):
+ *
+ * Normal cycle:
+ *   - Step 0:  all off, wait 250 ms
+ *   - Step 2:  LED 1–2 + 7–8 on, wait 50 ms
+ *   - Step 5:  all off, wait 100 ms
+ *   - Step 7:  LED 1–2 + 7–8 on, wait 50 ms
+ *   - Step 10: all off, wait 250 ms
+ *   - Step 12: LED 3–6 on, wait 50 ms
+ *   - Step 14: all off, wait 100 ms
+ *   - Step 16: LED 3–6 on, wait 50 ms
+ *   - Step 18: all off, wait 250 ms → restart
+ *
+ * Special behavior:
+ *   - Every 3rd cycle, after step 18, all LEDs (PA1, PA2, PA3) are switched on for 250 ms.
+ *
+ * Timing is based on @ref MAIN_LOOP_SLEEP ticks.
+ *
+ * @note Must be called periodically every 10 ms from the main loop.
+ * @note Depends on global flag ::bLedEnabled. If false, does nothing.
+ */
+void blinkLed(void)
+{
+    // --- precomputed constants (compile-time) ---
+    const uint8_t T50 = MS_TO_TICKS(50);   ///< 50 ms in ticks
+    const uint8_t T100 = MS_TO_TICKS(100); ///< 100 ms in ticks
+    const uint8_t T250 = MS_TO_TICKS(250); ///< 250 ms in ticks
+
+    // --- persistent state ---
+    static uint16_t counter = 0; ///< counts ticks for current state
+    static uint8_t state = 0;    ///< current step in the sequence
+    static uint8_t cycle = 0;    ///< cycle counter (0–2)
+
+    if (!bLedEnabled)
+        return;
+
+    counter++;
+
+    switch (state)
+    {
+    case 0: // all LEDs off, wait 250 ms
+        leds_off();
+        if (counter >= T250)
+        {
+            counter = 0;
+            state = 2;
+        }
+        break;
+
+    case 2: // LED 1–2 + 7–8 on, wait 50 ms
+        VPORTA.OUT |= (PA1_SET_MASK | PA3_SET_MASK);
+        if (counter >= T50)
+        {
+            counter = 0;
+            state = 5;
+        }
+        break;
+
+    case 5: // all LEDs off, wait 100 ms
+        leds_off();
+        if (counter >= T100)
+        {
+            counter = 0;
+            state = 7;
+        }
+        break;
+
+    case 7: // LED 1–2 + 7–8 on, wait 50 ms
+        VPORTA.OUT |= (PA1_SET_MASK | PA3_SET_MASK);
+        if (counter >= T50)
+        {
+            counter = 0;
+            state = 10;
+        }
+        break;
+
+    case 10: // all LEDs off, wait 250 ms
+        leds_off();
+        if (counter >= T250)
+        {
+            counter = 0;
+            state = 12;
+        }
+        break;
+
+    case 12: // LED 3–6 on, wait 50 ms
+        VPORTA.OUT |= PA2_SET_MASK;
+        if (counter >= T50)
+        {
+            counter = 0;
+            state = 14;
+        }
+        break;
+
+    case 14: // all LEDs off, wait 100 ms
+        leds_off();
+        if (counter >= T100)
+        {
+            counter = 0;
+            state = 16;
+        }
+        break;
+
+    case 16: // LED 3–6 on, wait 50 ms
+        VPORTA.OUT |= PA2_SET_MASK;
+        if (counter >= T50)
+        {
+            counter = 0;
+            state = 18;
+        }
+        break;
+
+    case 18: // all LEDs off, wait 250 ms
+        leds_off();
+        if (counter >= T250)
+        {
+            counter = 0;
+            if (++cycle >= 3)
+            {
+                cycle = 0;
+                state = 20; // special all-LEDs-on state
+            }
+            else
+            {
+                state = 0; // restart normal cycle
+            }
+        }
+        break;
+
+    case 20: // special: all LEDs on for 250 ms
+        VPORTA.OUT |= (PA1_SET_MASK | PA2_SET_MASK | PA3_SET_MASK);
+        if (counter >= T250)
+        {
+            counter = 0;
+            state = 0; // restart normal sequence
+        }
+        break;
     }
 }