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digitalWriteFast

Arduino library for faster digitalWrite() using direct port manipulation and macro for ease in pin assignments for constant pin numbers. It also provides faster pinMode() and digitalRead() functions as well as it adds a digitalToggleFast() function.

Available as Arduino library "digitalWriteFast".

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This is a fork of the subtree https://github.com/watterott/Arduino-Libs/tree/master/digitalWriteFast.

If pin number is no compile time constant, or the platform is not supported, then the regular Arduino functions digitalWrite() etc. are called.

• Use '#define pinNum 10' instead of int pinNum = 10;
• Use 'const int pinNum 10' instead of int pinNum = 10;

Usage

Include the library: #include <digitalWriteFast.h>

Macro definitions:

• digitalWriteFast(pinNum, state) (sets or clears pin/port faster)
• pinModeFast(pinNum, mode) (sets pin/port as input or output faster)
• digitalReadFast(pinNum)(reads the state of pin/port faster)
• digitalToggleFast(pinNum)(toggles the state of pin/port faster)

Parameters:

• pinNum is the number written on the Arduino board.
• state is weather pin is to be set HIGH or LOW
• mode is weather pin is to be set INPUT or OUTPUT or INPUT_PULLUP

Correct usage detection

Defining THROW_ERROR_IF_NOT_FAST would cause the macro to return an error during compilation, if the parameter is a variable and thus regular digital* functions must be called. This notifies the programmer the specific line where code is still slow.

Speed

For a 16 MHz Uno digitalWrite() is speed up from 5.8 µs to 125 ns, able to generate a 4 MHz signal instead of 86 kHz. More info in: /NOTES/NOTES.md

This is the waveform generated with the Timing example.

Compatibility

• Arduino Uno, Nano etc.
• Arduino Leonardo
• Arduino Mega
• Arduino with ATmega644 or Atmega644P chip
• Arduino with ATmega4809 chip
• Arduino with ATtiny chip

If you use megaTinyCore, you cannot use "#include digitalWriteFast.h" because megaTinyCore has it own digitalWriteFast function set, except digitalToggleFast(). <br/>

Revision History

Version 1.2.1

• Fixed preprocessor bug for ATtiny84.
• Support for megaTinyCore.

Version 1.2.0

• Removed warning of non existent PORTA etc.
• Added ATtiny1614.
• Fix attiny x4 pinout
• Added __digitalPinToBit for ATmega16.

Version 1.1.0

• Added TEENSYDUINO support.
• Added THROW_ERROR_IF_NOT_FAST functionality.
• Removed unnecessary compare > 0.
• Added Guard && defined(__digitalPinToPINReg) etc.
• Changed ifndef to if !defined().

Reference

This documentation is based on https://github.com/NicksonYap/digitalWriteFast/