##PWM
PWM stand for Pulse Width Modulation, it is a trick to get analog like result with your digital pins, do do so it emit a square wave by altering low and high current each cycle is divided in 256 parts, here you are my precious 8bits !!!
more about pwm here
####pwm waves
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| 0 % cycle ( 0 ) |
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| 5 v |
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|+-------------------------------------------------------+ 0 v |
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+----------------------------------------------------------------------------------+
+----------------------------------------------------------------------------------+
| 25 % cycle ( 64 ) |
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|+--+ +--+ +--+ +--+ 5 v |
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|+ +----------+ +----------+ +----------+ +----------+ 0 v |
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+----------------------------------------------------------------------------------+
+----------------------------------------------------------------------------------+
| 50 % cycle ( 127 ) |
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|+------+ +------+ +------+ +------+ 5 v |
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|+ +------+ +------+ +------+ +------+ 0 v |
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+----------------------------------------------------------------------------------+
+----------------------------------------------------------------------------------+
| 75 % cycle ( 191 ) |
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|+---------+ +---------+ +---------+ +---------+ 5 v |
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|+ +---+ +---+ +---+ +---+ 0 v |
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+----------------------------------------------------------------------------------+
+----------------------------------------------------------------------------------+
| 100 % cycle ( 255 ) |
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|+-------------------------------------------------------+ 5 v |
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| 0 v |
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+----------------------------------------------------------------------------------+