아두이노 스피드 업

https://stackabuse.com/speeding-up-arduino/

https://www.brightdevelopers.com/speed-arduino-code/

https://www.instructables.com/id/Arduino-is-Slow-and-how-to-fix-it/

http://forum.arduino.cc/index.php?topic=377891.0

https://www.arduino.cc/en/Reference/PortManipulation

http://skpang.co.uk/blog/archives/323

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STM32

http://www.stm32duino.com/viewtopic.php?f=18&t=2888&p=37578#p37593

//port/gpio oriented macros

#define IO_SET(port, pins)          port->regs->ODR |= (pins)       //set bits on port

#define IO_CLR(port, pins)          port->regs->ODR &=~(pins)       //clear bits on port

//fast routines through BRR/BSRR registers

#define FIO_SET(port, pins)         port->regs->BSRR = (pins) 

#define FIO_CLR(port, pins)         port->regs->BRR = (pins)

IO_SET/CLR  570ms  (118ns/IO) 8.5cycles 

FIO_SET/CLR 417ms  (42ns/FIO) 3.02cycles

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Fast Library

https://github.com/NicksonYap/digitalWriteFast

http://masteringarduino.blogspot.com/2013/10/fastest-and-smallest-digitalread-and.html