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56e6ed8233
FEATURE_STEPPER_MOTOR
Removed OPTION_STEPPER_MOTOR_MAX_50_KHZ. Too much overhead from interrupts.
Implemented faster digital writes using digitalWriteFast library (library now included in Github)
Added OPTION_STEPPER_DO_NOT_USE_DIGITALWRITEFAST_LIBRARY to disable digitalWriteFast library use
65 lines
2.8 KiB
Markdown
Executable File
65 lines
2.8 KiB
Markdown
Executable File
# digitalWriteFast
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Arduino library for faster `digitalWrite()` using direct port manipulation and macro for ease in pin assignments.
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Which actually also does faster `pinMode()` and `digitalRead()`.
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## Usage
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Include the library:
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`#include <digitalWriteFast.h>`
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Macro definitions:
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* `digitalWriteFast(pinNum, state)` (sets or clears pin/port faster)
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* `pinModeFast(pinNum, mode)` (sets pin/port as input or output faster)
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* `digitalReadFast(pinNum)`(reads the state of pin/port faster)
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Parameters:
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* `pinNum` is the number written on the Arduino board.
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* `state` is weather pin is to be set `HIGH` or `LOW`
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* `mode` is weather pin is to be set `INPUT` or `OUTPUT`
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In order to toggle fast, all the three parameters above must be constant or defined by the macro for ease in changes during compilation.
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For example:
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* use '#define pinNum 10' instead of `int pinNum = 10;`
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* use 'const int pinNum 10' instead of `int pinNum = 10;`
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Setting the parameter as a variable would cause the macro to return an error during compilation.
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This makes sure `digitalWriteFast` that produces faster toggling, and notifies the programmer the specific area where toggling is slow. Otherwise, use normal `digitalWrite`
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This is opposed to the forked library form Watterott, where if a variable is used as the parameter, the macro would revert to use sold `digitalWrite`, and remain undetected.
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## Speed
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The regular `digitalWrite()` in Arduino Uno core (16MHz) takes about **6280nS** while `digitalWriteFast()` port manipulation takes **125nS**.
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> More info in: [/NOTES/NOTES.md](/NOTES/NOTES.md)
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This is a huge difference, especially or timing sensitive applications.
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Direct port manipulation is troublesome where one has to refer to the pin assignment of the package and manipulate specific ports, instead of pin numbers on the Arduino board.
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This library makes it easier by using `digitalWriteFast()` and the macro will replace it will the approritate port manipulation commands.
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## Compatibility
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* Arduino Due
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* Arduino Zero
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* Arduino Mega
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* Arduino with ATmega644 or Atmega644P chip
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* Arduino Leonardo
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* Arduino Uno (I have only tested with uno)
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If not in the list, the macro will revert back to `digitalWrite()`, `pinMode()` or `digitalRead()`
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## Installation
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1. Download the repo as zip, extract and place into Arduino IDE libraries folder.
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2. Rename "digitalWriteFast-master" to "digitalWriteFast" Arduino IDE does not accept dash character.
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## Reference
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Fork of Watterott's https://github.com/watterott/Arduino-Libs/tree/master/digitalWriteFast
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I just forked the whole repo, and delete unrelated files, I tried sparse checkout and gave up.
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Watterott's digitalWriteFast could have used the below links as referrence.
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* https://code.google.com/archive/p/digitalwritefast/downloads
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* http://forum.arduino.cc/index.php?topic=46896.0
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