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