uart.c

/*************************************************************************
Title:    Interrupt UART library with receive/transmit circular buffers
Author:   Peter Fleury <pfleury@gmx.ch>   http://jump.to/fleury
File:     $Id: uart.c,v 1.6.2.2 2009/11/29 08:56:12 Peter Exp $
Software: AVR-GCC 4.1, AVR Libc 1.4.6 or higher
Hardware: any AVR with built-in UART, 
License:  GNU General Public License 
          
DESCRIPTION:
    An interrupt is generated when the UART has finished transmitting or
    receiving a byte. The interrupt handling routines use circular buffers
    for buffering received and transmitted data.
    
    The UART_RX_BUFFER_SIZE and UART_TX_BUFFER_SIZE variables define
    the buffer size in bytes. Note that these variables must be a 
    power of 2.
    
USAGE:
    Refere to the header file uart.h for a description of the routines. 
    See also example test_uart.c.

NOTES:
    Based on Atmel Application Note AVR306
                    
LICENSE:
    Copyright (C) 2006 Peter Fleury

    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
    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.
                        
*************************************************************************/
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include "uart.h"
#include "main.h"

/*
 *  constants and macros
 */

/* size of RX/TX buffers */
#define UART_RX_BUFFER_MASK ( UART_RX_BUFFER_SIZE - 1)
#define UART_TX_BUFFER_MASK ( UART_TX_BUFFER_SIZE - 1)

#if ( UART_RX_BUFFER_SIZE & UART_RX_BUFFER_MASK )
#error RX buffer size is not a power of 2
#endif
#if ( UART_TX_BUFFER_SIZE & UART_TX_BUFFER_MASK )
#error TX buffer size is not a power of 2
#endif

//FIXME the following defines still need fixing of the interrupt stuff for most AVRs
#if defined(__AVR_AT90S2313__) \
 || defined(__AVR_AT90S4414__) || defined(__AVR_AT90S4434__) \
 || defined(__AVR_AT90S8515__) || defined(__AVR_AT90S8535__) \
 || defined(__AVR_ATmega103__)
 /* old AVR classic or ATmega103 with one UART */
 #define AT90_UART
 #define UART0_RECEIVE_INTERRUPT   SIG_UART_RECV
 #define UART0_TRANSMIT_INTERRUPT  SIG_UART_DATA
 #define UART0_STATUS   USR
 #define UART0_CONTROL  UCR
 #define UART0_DATA     UDR  
 #define UART0_UDRIE    UDRIE
#elif defined(__AVR_AT90S2333__) || defined(__AVR_AT90S4433__)
 /* old AVR classic with one UART */
 #define AT90_UART
 #define UART0_RECEIVE_INTERRUPT   SIG_UART_RECV
 #define UART0_TRANSMIT_INTERRUPT  SIG_UART_DATA
 #define UART0_STATUS   UCSRA
 #define UART0_CONTROL  UCSRB
 #define UART0_DATA     UDR 
 #define UART0_UDRIE    UDRIE
#elif  defined(__AVR_ATmega8__)  || defined(__AVR_ATmega16__) || defined(__AVR_ATmega32__) \
  || defined(__AVR_ATmega8515__) || defined(__AVR_ATmega8535__) \
  || defined(__AVR_ATmega323__)
  /* ATmega with one USART */
 #define ATMEGA_USART
 #define UART0_RECEIVE_INTERRUPT   SIG_UART_RECV
 #define UART0_TRANSMIT_INTERRUPT  SIG_UART_DATA
 #define UART0_STATUS   UCSRA
 #define UART0_CONTROL  UCSRB
 #define UART0_DATA     UDR
 #define UART0_UDRIE    UDRIE
#elif defined(__AVR_ATmega163__) 
  /* ATmega163 with one UART */
 #define ATMEGA_UART
 #define UART0_RECEIVE_INTERRUPT   SIG_UART_RECV
 #define UART0_TRANSMIT_INTERRUPT  SIG_UART_DATA
 #define UART0_STATUS   UCSRA
 #define UART0_CONTROL  UCSRB
 #define UART0_DATA     UDR
 #define UART0_UDRIE    UDRIE
#elif defined(__AVR_ATmega162__) 
 /* ATmega with two USART */
 #define ATMEGA_USART0
 #define ATMEGA_USART1
 #define UART0_RECEIVE_INTERRUPT   SIG_USART0_RECV
 #define UART0_TRANSMIT_INTERRUPT  SIG_USART0_DATA
 #define UART0_STATUS   UCSR0A
 #define UART0_CONTROL  UCSR0B
 #define UART0_DATA     UDR0
 #define UART0_UDRIE    UDRIE0
#elif defined(__AVR_ATmega64__) || defined(__AVR_ATmega128__) 
 /* ATmega with two USART */
 #define ATMEGA_USART0
 #define ATMEGA_USART1
 #define UART0_RECEIVE_INTERRUPT   SIG_UART0_RECV
 #define UART0_TRANSMIT_INTERRUPT  SIG_UART0_DATA
 #define UART0_STATUS   UCSR0A
 #define UART0_CONTROL  UCSR0B
 #define UART0_DATA     UDR0
 #define UART0_UDRIE    UDRIE0
#elif defined(__AVR_ATmega161__)
 /* ATmega with UART */
 #error "AVR ATmega161 currently not supported by this libaray !"
#elif defined(__AVR_ATmega169__) 
 /* ATmega with one USART */
 #define ATMEGA_USART
 #define UART0_RECEIVE_INTERRUPT   SIG_USART_RECV
 #define UART0_TRANSMIT_INTERRUPT  SIG_USART_DATA
 #define UART0_STATUS   UCSRA
 #define UART0_CONTROL  UCSRB
 #define UART0_DATA     UDR
 #define UART0_UDRIE    UDRIE
#elif defined(__AVR_ATmega48__) ||defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__) || defined(__AVR_ATmega48P__) || defined(__AVR_ATmega88P__) || defined(__AVR_ATmega168P__) || defined(__AVR_ATmega328P__)
 /* ATmega with one USART */
 #define ATMEGA_USART0
 #define UART0_RECEIVE_INTERRUPT   USART_RX_vect
 #define UART0_TRANSMIT_INTERRUPT  USART_UDRE_vect
 #define UART0_STATUS   UCSR0A
 #define UART0_CONTROL  UCSR0B
 #define UART0_DATA     UDR0
 #define UART0_UDRIE    UDRIE0
#elif defined(__AVR_ATtiny2313__)
 #define ATMEGA_USART
 #define UART0_RECEIVE_INTERRUPT   SIG_USART0_RX 
 #define UART0_TRANSMIT_INTERRUPT  SIG_USART0_UDRE
 #define UART0_STATUS   UCSRA
 #define UART0_CONTROL  UCSRB
 #define UART0_DATA     UDR
 #define UART0_UDRIE    UDRIE
#elif defined(__AVR_ATmega329__) ||defined(__AVR_ATmega3290__) ||\
      defined(__AVR_ATmega649__) ||defined(__AVR_ATmega6490__) ||\
      defined(__AVR_ATmega325__) ||defined(__AVR_ATmega3250__) ||\
      defined(__AVR_ATmega645__) ||defined(__AVR_ATmega6450__)
  /* ATmega with one USART */
  #define ATMEGA_USART0
  #define UART0_RECEIVE_INTERRUPT   SIG_UART_RECV
  #define UART0_TRANSMIT_INTERRUPT  SIG_UART_DATA
  #define UART0_STATUS   UCSR0A
  #define UART0_CONTROL  UCSR0B
  #define UART0_DATA     UDR0
  #define UART0_UDRIE    UDRIE0
#elif defined(__AVR_ATmega2560__) || defined(__AVR_ATmega2561__) || defined(__AVR_ATmega1280__)  || defined(__AVR_ATmega1281__) || defined(__AVR_ATmega640__)
/* ATmega with two USART */
  #define ATMEGA_USART0
  #define ATMEGA_USART1
  #define UART0_RECEIVE_INTERRUPT   USART0_RX_vect
  #define UART0_TRANSMIT_INTERRUPT  USART0_UDRE_vect
  #define UART0_STATUS   UCSR0A
  #define UART0_CONTROL  UCSR0B
  #define UART0_DATA     UDR0
  #define UART0_UDRIE    UDRIE0
#elif defined(__AVR_ATmega644__)
 /* ATmega with one USART */
 #define ATMEGA_USART0
 #define UART0_RECEIVE_INTERRUPT   SIG_USART_RECV
 #define UART0_TRANSMIT_INTERRUPT  SIG_USART_DATA
 #define UART0_STATUS   UCSR0A
 #define UART0_CONTROL  UCSR0B
 #define UART0_DATA     UDR0
 #define UART0_UDRIE    UDRIE0
#elif defined(__AVR_ATmega164P__) || defined(__AVR_ATmega324P__) || defined(__AVR_ATmega644P__)
 /* ATmega with two USART */
 #define ATMEGA_USART0
 #define ATMEGA_USART1
 #define UART0_RECEIVE_INTERRUPT   SIG_USART_RECV
 #define UART0_TRANSMIT_INTERRUPT  SIG_USART_DATA
 #define UART0_STATUS   UCSR0A
 #define UART0_CONTROL  UCSR0B
 #define UART0_DATA     UDR0
 #define UART0_UDRIE    UDRIE0
#else
 #error "no UART definition for MCU available"
#endif


/*
 *  module global variables
 */
static volatile unsigned char UART_TxBuf[UART_TX_BUFFER_SIZE];
static volatile unsigned char UART_TxHead;
static volatile unsigned char UART_TxTail;

ISR(UART0_RECEIVE_INTERRUPT)
{
    unsigned char data;
    //unsigned char usr;
    //unsigned char lastRxError;
 
 
    /* read UART status register and UART data register */ 
    //usr  = UART0_STATUS;
    data = UART0_DATA;
    
    /*
#if defined( AT90_UART )
    lastRxError = (usr & (_BV(FE)|_BV(DOR)) );
#elif defined( ATMEGA_USART )
    lastRxError = (usr & (_BV(FE)|_BV(DOR)) );
#elif defined( ATMEGA_USART0 )
    lastRxError = (usr & (_BV(FE0)|_BV(DOR0)) );
#elif defined ( ATMEGA_UART )
    lastRxError = (usr & (_BV(FE)|_BV(DOR)) );
#endif
    */
        
    if (!(UCSR0A & (_BV(FE0) | _BV(DOR0))))
        uart_handle(data);
}


ISR(UART0_TRANSMIT_INTERRUPT)
/*************************************************************************
Function: UART Data Register Empty interrupt
Purpose:  called when the UART is ready to transmit the next byte
**************************************************************************/
{
    unsigned char tmptail;

    
    if ( UART_TxHead != UART_TxTail) {
        /* calculate and store new buffer index */
        tmptail = (UART_TxTail + 1) & UART_TX_BUFFER_MASK;
        UART_TxTail = tmptail;
        /* get one byte from buffer and write it to UART */
        UART0_DATA = UART_TxBuf[tmptail];  /* start transmission */
    }else{
        /* tx buffer empty, disable UDRE interrupt */
        UART0_CONTROL &= ~_BV(UART0_UDRIE);
    }
}


/*************************************************************************
Function: uart_init()
Purpose:  initialize UART and set baudrate
Input:    baudrate using macro UART_BAUD_SELECT()
Returns:  none
**************************************************************************/
void uart_init(unsigned int baudrate)
{
    UART_TxHead = 0;
    UART_TxTail = 0;
    
#if defined( AT90_UART )
    /* set baud rate */
    UBRR = (unsigned char)baudrate; 

    /* enable UART receiver and transmmitter and receive complete interrupt */
    UART0_CONTROL = _BV(RXCIE)|_BV(RXEN)|_BV(TXEN);

#elif defined (ATMEGA_USART)
    /* Set baud rate */
    if ( baudrate & 0x8000 )
    {
    	 UART0_STATUS = (1<<U2X);  //Enable 2x speed 
    	 baudrate &= ~0x8000;
    }
    UBRRH = (unsigned char)(baudrate>>8);
    UBRRL = (unsigned char) baudrate;
   
    /* Enable USART receiver and transmitter and receive complete interrupt */
    UART0_CONTROL = _BV(RXCIE)|(1<<RXEN)|(1<<TXEN);
    
    /* Set frame format: asynchronous, 8data, no parity, 1stop bit */
    #ifdef URSEL
    UCSRC = (1<<URSEL)|(3<<UCSZ0);
    #else
    UCSRC = (3<<UCSZ0);
    #endif 
    
#elif defined (ATMEGA_USART0 )
    /* Set baud rate */
    if ( baudrate & 0x8000 ) 
    {
   		UART0_STATUS = (1<<U2X0);  //Enable 2x speed 
   		baudrate &= ~0x8000;
   	}
    UBRR0H = (unsigned char)(baudrate>>8);
    UBRR0L = (unsigned char) baudrate;

    /* Enable USART receiver and transmitter and receive complete interrupt */
    UART0_CONTROL = _BV(RXCIE0)|(1<<RXEN0)|(1<<TXEN0);
    
    /* Set frame format: asynchronous, 8data, no parity, 1stop bit */
    #ifdef URSEL0
    UCSR0C = (1<<URSEL0)|(3<<UCSZ00);
    #else
    UCSR0C = (3<<UCSZ00);
    #endif 

#elif defined ( ATMEGA_UART )
    /* set baud rate */
    if ( baudrate & 0x8000 ) 
    {
    	UART0_STATUS = (1<<U2X);  //Enable 2x speed 
    	baudrate &= ~0x8000;
    }
    UBRRHI = (unsigned char)(baudrate>>8);
    UBRR   = (unsigned char) baudrate;

    /* Enable UART receiver and transmitter and receive complete interrupt */
    UART0_CONTROL = _BV(RXCIE)|(1<<RXEN)|(1<<TXEN);

#endif

}/* uart_init */

/*************************************************************************
Function: uart_putc()
Purpose:  write byte to ringbuffer for transmitting via UART
Input:    byte to be transmitted
Returns:  none          
**************************************************************************/
void uart_putc(unsigned char data)
{
    unsigned char tmphead;

    tmphead = (UART_TxHead + 1) & UART_TX_BUFFER_MASK;
    
    while ( tmphead == UART_TxTail );/* wait for free space in buffer */
    
    UART_TxBuf[tmphead] = data;
    UART_TxHead = tmphead;

    /* enable UDRE interrupt */
    UART0_CONTROL    |= _BV(UART0_UDRIE);
}

void uart_putc_nonblocking(unsigned char data){
    unsigned char tmphead;
    
    tmphead  = (UART_TxHead + 1) & UART_TX_BUFFER_MASK;
    
    if(tmphead == UART_TxTail) //if there is no free space in buffer
        return;
    
    UART_TxBuf[tmphead] = data;
    UART_TxHead = tmphead;

    //enable UDRE interrupt
    UART0_CONTROL    |= _BV(UART0_UDRIE);
}


/*************************************************************************
Function: uart_puts()
Purpose:  transmit string to UART
Input:    string to be transmitted
Returns:  none          
**************************************************************************/
void uart_puts(const char *s )
{
    while (*s) 
      uart_putc(*s++);

}/* uart_puts */


/*************************************************************************
Function: uart_puts_p()
Purpose:  transmit string from program memory to UART
Input:    program memory string to be transmitted
Returns:  none
**************************************************************************/
void uart_puts_p(const char *progmem_s )
{
    register char c;
    
    while ( (c = pgm_read_byte(progmem_s++)) ) 
      uart_putc(c);

}/* uart_puts_p */