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avr_demo/blog/simple_usart/uart.c

41 lines
770 B
C

#include <avr/io.h>
#include <stdio.h>
#ifndef F_CPU
#define F_CPU 16000000UL
#endif
#ifndef BAUD
#define BAUD 9600
#endif
#include <util/setbaud.h>
/* http://www.cs.mun.ca/~rod/Winter2007/4723/notes/serial/serial.html */
void uart_init(void) {
UBRR0H = UBRRH_VALUE;
UBRR0L = UBRRL_VALUE;
#if USE_2X
UCSR0A |= _BV(U2X0);
#else
UCSR0A &= ~(_BV(U2X0));
#endif
UCSR0C = _BV(UCSZ01) | _BV(UCSZ00); /* 8-bit data */
UCSR0B = _BV(RXEN0) | _BV(TXEN0); /* Enable RX and TX */
}
void uart_putchar(char c, FILE *stream) {
if (c == '\n') {
uart_putchar('\r', stream);
}
loop_until_bit_is_set(UCSR0A, UDRE0);
UDR0 = c;
}
char uart_getchar(FILE *stream) {
loop_until_bit_is_set(UCSR0A, RXC0);
return UDR0;
}