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