doorlockd-mirror/avr-code/uart.c

/*
 * doorlock-avr, AVR code of Binary Kitchen's doorlock
 *
 * Copyright (c) Binary Kitchen, 2018
 *
 * Authors:
 *  Ralf Ramsauer <ralf@binary-kitchen.de>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 */

#include <stddef.h>
#include <avr/interrupt.h>
#include <avr/io.h>

#include "uart.h"

#define UBRR_VAL ((F_OSC+UART_BAUD*8)/(UART_BAUD*16)-1)
#define BAUD_REAL (F_OSC/(16*(UBRR_VAL+1)))
#define BAUD_ERROR ((BAUD_REAL*1000)/UART_BAUD)

#if ((BAUD_ERROR<985) || (BAUD_ERROR>1010))
  #warn BAUD_ERROR
  #error Choose another crystal. Baud error too high.
#endif

void uart_init()
{
	// Enable receive and transmit
	UCSRB = (1<<RXEN)|(1<<TXEN)|(1<<RXCIE);

	// Asynchronous mode, 8N1
	UCSRC = (1<<UCSZ1)|(1<<UCSZ0);

	UBRRH = UBRR_VAL >> 8;
	UBRRL = UBRR_VAL & 0xFF;
}

void uart_putc(const char c)
{
	while ( !(UCSRA & (1<<UDRE)) );
	UDR = (const unsigned char)c;
}

void uart_puts(const char* str)
{
	do {
		uart_putc(*str);
	} while(*++str);
}