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avr_demo/hello_uart/uart.c

35 lines
806 B
C

#include <avr/io.h>
#include <stdio.h>
#ifndef BAUD
#define BAUD 9600
#endif
#include <util/setbaud.h>
/* http://www.cs.mun.ca/~rod/Winter2007/4723/notes/serial/serial.html */
FILE uart_output = FDEV_SETUP_STREAM(uart_putchar, NULL, _FDEV_SETUP_WRITE);
FILE uart_input = FDEV_SETUP_STREAM(NULL, uart_getchar, _FDEV_SETUP_READ);
void uart_init(void) {
UBRR0H = UBRRH_VALUE;
UBRR0L = UBRRL_VALUE;
UCSR0C = _BV(UCSZ01) | _BV(UCSZ00); /* 8-bit data */
UCSR0B = _BV(RXEN0) | _BV(TXEN0); /* Enable RX and TX */
}
int uart_putchar(char c, FILE *stream) {
if (c == '\n') {
uart_putchar('\r', stream);
}
loop_until_bit_is_set(UCSR0A, UDRE0);
UDR0 = c;
return 0;
}
int uart_getchar(FILE *stream) {
loop_until_bit_is_set(UCSR0A, RXC0);
return UDR0;
}