One-shot LED Trigger ==================== This is a LED trigger useful for signaling the user of an event where there are no clear trap points to put standard led-on and led-off settings. Using this trigger, the application needs only to signal the trigger when an event has happened, than the trigger turns the LED on and than keeps it off for a specified amount of time. This trigger is meant to be usable both for sporadic and dense events. In the first case, the trigger produces a clear single controlled blink for each event, while in the latter it keeps blinking at constant rate, as to signal that the events are arriving continuously. A one-shot LED only stays in a constant state when there are no events. An additional "invert" property specifies if the LED has to stay off (normal) or on (inverted) when not rearmed. The trigger can be activated from user space on led class devices as shown below: echo oneshot > trigger This adds the following sysfs attributes to the LED: delay_on - specifies for how many milliseconds the LED has to stay at LED_FULL brightness after it has been armed. Default to 100 ms. delay_off - specifies for how many milliseconds the LED has to stay at LED_OFF brightness after it has been armed. Default to 100 ms. invert - reverse the blink logic. If set to 0 (default) blink on for delay_on ms, then blink off for delay_off ms, leaving the LED normally off. If set to 1, blink off for delay_off ms, then blink on for delay_on ms, leaving the LED normally on. Setting this value also immediately change the LED state. shot - write any non-empty string to signal an events, this starts a blink sequence if not already running. Example use-case: network devices, initialization: echo oneshot > trigger # set trigger for this led echo 33 > delay_on # blink at 1 / (33 + 33) Hz on continuous traffic echo 33 > delay_off interface goes up: echo 1 > invert # set led as normally-on, turn the led on packet received/transmitted: echo 1 > shot # led starts blinking, ignored if already blinking interface goes down echo 0 > invert # set led as normally-off, turn the led off