Software Defined High-speed Asynchronous Serial Transmitter

HAST is a C++11 template that generates a transmitter routine for a software UART. It deploys unrolled loop with variable padding technique for generating precise timing between bits, and a short sequence (3 cycles) for driving the output. Such approach allows baud rates up to CLOCK/3.

HAST is a header-only library. Include hast.hpp and instantiate hast::avr::trasmitter as the following

#include "hast.hpp"

void hast_putc(char c) {
	hast::avr::transmitter<
		1000000,							/* 1 MHz			*/
		hast::_115200,					/* 115200 baud	*/
		ADDR_OF(PORTB), PORTB3, 0,	/* pin PORTB3	*/
		hast::stopbits::one			/* one stop bit	*/ 
	>::send(c);
}

Built-in RC-oscillator is calibrated for certain conditions. If operating conditions differ, RC-oscillator may deviate from the expected frequency. This deviation may have negative impact on HAST operations. To improve results, you may need fine tune the RC-oscillator.

Baudrate 921600, clock 8 MHz