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- * Pattern format for LED pattern trigger
- The pattern is given by a series of tuples, of brightness and duration (ms).
- The LED is expected to traverse the series and each brightness value for the
- specified duration. Duration of 0 means brightness should immediately change to
- new value, and writing malformed pattern deactivates any active one.
- 1. For gradual dimming, the dimming interval now is set as 50 milliseconds. So
- the tuple with duration less than dimming interval (50ms) is treated as a step
- change of brightness, i.e. the subsequent brightness will be applied without
- adding intervening dimming intervals.
- The gradual dimming format of the software pattern values should be:
- "brightness_1 duration_1 brightness_2 duration_2 brightness_3 duration_3 ...".
- For example (using sysfs interface):
- echo 0 1000 255 2000 > pattern
- It will make the LED go gradually from zero-intensity to max (255) intensity in
- 1000 milliseconds, then back to zero intensity in 2000 milliseconds:
- LED brightness
- ^
- 255-| / \ / \ /
- | / \ / \ /
- | / \ / \ /
- | / \ / \ /
- 0-| / \/ \/
- +---0----1----2----3----4----5----6------------> time (s)
- 2. To make the LED go instantly from one brightness value to another, we should
- use zero-time lengths (the brightness must be same as the previous tuple's). So
- the format should be: "brightness_1 duration_1 brightness_1 0 brightness_2
- duration_2 brightness_2 0 ...".
- For example (using sysfs interface):
- echo 0 1000 0 0 255 2000 255 0 > pattern
- It will make the LED stay off for one second, then stay at max brightness for
- two seconds:
- LED brightness
- ^
- 255-| +---------+ +---------+
- | | | | |
- | | | | |
- | | | | |
- 0-| -----+ +----+ +----
- +---0----1----2----3----4----5----6------------> time (s)
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