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44 lines
1.5 KiB
Markdown
44 lines
1.5 KiB
Markdown
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# PinOutGroup
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Arduino library to group up to 16 outputs into one command
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# Description
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A PinOutGroup is a number of output pins that can be set by means of one **write()** command.
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The PinOutGroup remembers the last values set per pin and will not do a digitalWrite()
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if the pin is already in the right state. Think of it as caching the state.
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If a (group of) pin(s) is updated often this saves cpu cycles however this feature
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has overhead which works contra productive when you toggle the pins in a group. So use with care.
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### performance intermezzo
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Assume that on average 50% of the pins are in the right state in a group.
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This means that on average half the pins are actually changed. By bypassing
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the (relative) expensive **digitalWrite()** time is gained.
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Actual performance gains depends very much on the data written.
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It is worth to do a small investigation for this. See e.g. 7 segment demo.
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### interface
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**clear()** resets all pins in the group to LOW and sets the size ot zero
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so one can repopulate.
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**add()** adds a predefined array of pin numbers of a single pin to the group.
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**write(value)** writes a 16 bits unsigned int to max 16 pins.
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**write(idx, value)** sets a single pin of the internal array withindex
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idx to value. This one is faster than writing to the whole group for a single
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change. The user must keep track of the right index nr.
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**read()** reads back the last written value to the pins as an unsigend int.
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**size()** and **free()** give information about the group.
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# Operation
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See examples
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