lib/led: add some clarifying comments

src/lib/led/led.cpp

@@ -70,7 +70,7 @@ int LedController::update(LedControlData &control_data)
 
 	// handle state updates
 	hrt_abstime now = hrt_absolute_time();
-	uint16_t blink_delta_t = (uint16_t)((now - _last_update_call) / 100);
+	uint16_t blink_delta_t = (uint16_t)((now - _last_update_call) / 100); // Note: this is in 0.1ms
 
 	for (int i = 0; i < BOARD_MAX_LEDS; ++i) {
 		bool do_not_change_state = false;
@@ -106,7 +106,7 @@ int LedController::update(LedControlData &control_data)
 					_states[i].current_blinking_time -= current_blink_duration;
 
 					if (cur_data.blink_times_left == 254) {
-						// handle toggling for infinite case
+						// handle toggling for infinite case: toggle between 254 and 255
 						cur_data.blink_times_left = 255;
 						do_not_change_state = true;
 

src/lib/led/led.h

@@ -91,12 +91,12 @@ public:
 	 */
 	int update(LedControlData &control_data);
 
-	static const int BLINK_FAST_DURATION = 100 *
+	static const int BLINK_FAST_DURATION = 100 * 1000; /**< duration of half a blinking cycle
-					       1000; ///< duration of half a blinking cycle (on-to-off and off-to-on) in us
+									(on-to-off and off-to-on) in us */
-	static const int BLINK_NORMAL_DURATION = 500 *
+	static const int BLINK_NORMAL_DURATION = 500 * 1000; /**< duration of half a blinking cycle
-			1000; ///< duration of half a blinking cycle (on-to-off and off-to-on) in us
+									(on-to-off and off-to-on) in us */
-	static const int BLINK_SLOW_DURATION = 2000 *
+	static const int BLINK_SLOW_DURATION = 2000 * 1000; /**< duration of half a blinking cycle
-					       1000; ///< duration of half a blinking cycle (on-to-off and off-to-on) in us
+									(on-to-off and off-to-on) in us */
 
 	int led_control_subscription() const { return _led_control_sub; }
 
@@ -135,7 +135,7 @@ private:
 
 	struct PerLedData {
 		PerPriorityData priority[led_control_s::MAX_PRIORITY + 1];
-		uint16_t current_blinking_time = 0; ///< how long the Led was in current state (in 0.1 ms)
+		uint16_t current_blinking_time = 0; ///< how long the Led was in current state (in 0.1 ms, wraps if > 6.5s)
 		NextState next_state;
 	};