esusart.h

/* vim:fdm=marker ts=4 et ai
 * {{{
 *
 * Copyright (c) 2008 by Christian Dietrich <stettberger@dokucode.de>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * For more information on the GPL, please go to:
 * http://www.gnu.org/copyleft/gpl.html
 }}} */

#include "config.h"
#include <stdint.h>

#ifndef _USART_H
#define _USART_H


/* The baudrate had to be baudrate/100 */
#ifndef TEENSY_SUPPORT
uint16_t usart_baudrate(uint16_t baudrate);
#endif

#ifndef USE_USART
#define USE_USART
#endif

#define _usart_cat_(a,b) a ## b
#define _usart_cat(a,b) _usart_cat_(a,b)

#if !defined(UDR0) || !defined(USE_USART)
#undef USE_USART
#define USE_USART
#endif

#ifndef USART_TX_vect
#  if defined(USART0_TX_vect)
#    define USART_TX_vect USART0_TX_vect
#    define USART_RX_vect USART0_RX_vect
#  elif defined(USART0_TXC_vect)
#    define USART_TX_vect USART0_TXC_vect
#    define USART_RX_vect USART0_RXC_vect
#  elif defined(USART_TXC_vect)
#    define USART_TX_vect USART_TXC_vect
#    define USART_RX_vect USART_RXC_vect
#  else
#    error "I hate avr-libc"
#  endif
#endif



// Sugar for the avr-libc
#if !defined(USART0_TX0_vect) && defined(USART0_TXC_vect)
#  define USART0_TX_vect USART0_TXC_vect
#  define USART1_TX_vect USART1_TXC_vect
#  define USART0_RX_vect USART0_RXC_vect
#  define USART1_RX_vect USART1_RXC_vect
#endif

#define usart(a, ...) _usart_cat(a, _usart_cat(USE_USART, __VA_ARGS__))

/* We love the preprocessor */
#if defined(URSEL) || defined(URSEL0)
#define _BV_URSEL _BV(usart(URSEL))
#else
#define _BV_URSEL 0
#endif

/* If the Baudrate isn't set by the module which is using usart.h */
#ifndef BAUD
#define BAUD 19200
#endif

/* We use setbaud.h from the avr-libc */
#include "setbaud.h"

/* This is used in generate_usart_init() */
#if USE_2X
#define USART_2X() usart(UCSR,A) |= (1 << usart(U2X))
#else
#define USART_2X() usart(UCSR,A) &= ~(1 << usart(U2X))
#endif


/* init the usart module */
#define generate_usart_init() \
static void \
usart_init(void) \
{\
    /* The ATmega644 datasheet suggests to clear the global\
       interrupt flags on initialization ... */\
    uint8_t sreg = SREG; cli(); \
    usart(UBRR,H) = HI8(UBRRH_VALUE); \
    usart(UBRR,L) = LO8(UBRRL_VALUE); ;\
    /* set mode: 8 bits, 1 stop, no parity, asynchronous usart */ \
    /*   and set URSEL, if present, */ \
    usart(UCSR,C) = _BV(usart(UCSZ,0)) | _BV(usart(UCSZ,1)) | _BV_URSEL; \
    /* Enable the RX interrupt and receiver and transmitter */ \
    usart(UCSR,B) |= _BV(usart(TXEN)) | _BV(usart(RXEN)) | _BV(usart(RXCIE));\
    /* Set or not set the 2x mode */ \
    USART_2X(); \
    /* Go! */ \
    SREG = sreg;\
}

#endif