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 1.5.2.10 2005/11/15 19:49:12 peter Exp $
Software: AVR-GCC 3.3 
Hardware: any AVR with built-in UART, 
          tested on AT90S8515 at 4 Mhz and ATmega at 1Mhz

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

*************************************************************************/
// Martin Thomas:
// minor reformating
// minor updates for ATmega644 and ATmega164P/324P/644P
// remark: this is based on a pre-GPL version, no need to include the
//         full source to end-users

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

#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 UART1_RECEIVE_INTERRUPT   SIG_USART1_RECV
 #define UART0_TRANSMIT_INTERRUPT  SIG_USART0_DATA
 #define UART1_TRANSMIT_INTERRUPT  SIG_USART1_DATA
 #define UART0_STATUS   UCSR0A
 #define UART0_CONTROL  UCSR0B
 #define UART0_DATA     UDR0
 #define UART0_UDRIE    UDRIE0
 #define UART1_STATUS   UCSR1A
 #define UART1_CONTROL  UCSR1B
 #define UART1_DATA     UDR1
 #define UART1_UDRIE    UDRIE1
#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 UART1_RECEIVE_INTERRUPT   SIG_UART1_RECV
 #define UART0_TRANSMIT_INTERRUPT  SIG_UART0_DATA
 #define UART1_TRANSMIT_INTERRUPT  SIG_UART1_DATA
 #define UART0_STATUS   UCSR0A
 #define UART0_CONTROL  UCSR0B
 #define UART0_DATA     UDR0
 #define UART0_UDRIE    UDRIE0
 #define UART1_STATUS   UCSR1A
 #define UART1_CONTROL  UCSR1B
 #define UART1_DATA     UDR1
 #define UART1_UDRIE    UDRIE1
#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__)
 /* 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_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_ATmega644__)
 /* ATmega with one USART - still using old-style vector-labels */
 #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 - still using old-style vector-labels */
 #define ATMEGA_USART0
 #define ATMEGA_USART1
 #define UART0_RECEIVE_INTERRUPT     SIG_USART_RECV
 #define UART1_RECEIVE_INTERRUPT     SIG_USART1_RECV
 #define UART0_TRANSMIT_INTERRUPT    SIG_USART_DATA
 #define UART1_TRANSMIT_INTERRUPT    SIG_USART1_DATA
 #define UART0_STATUS   UCSR0A
 #define UART0_CONTROL  UCSR0B
 #define UART0_DATA     UDR0
 #define UART0_UDRIE    UDRIE0
 #define UART1_STATUS   UCSR1A
 #define UART1_CONTROL  UCSR1B
 #define UART1_DATA     UDR1
 #define UART1_UDRIE    UDRIE1

#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_RxBuf[UART_RX_BUFFER_SIZE];
static volatile unsigned char UART_TxHead;
static volatile unsigned char UART_TxTail;
static volatile unsigned char UART_RxHead;
static volatile unsigned char UART_RxTail;
static volatile unsigned char UART_LastRxError;

#if defined( ATMEGA_USART1 )
static volatile unsigned char UART1_TxBuf[UART_TX_BUFFER_SIZE];
static volatile unsigned char UART1_RxBuf[UART_RX_BUFFER_SIZE];
static volatile unsigned char UART1_TxHead;
static volatile unsigned char UART1_TxTail;
static volatile unsigned char UART1_RxHead;
static volatile unsigned char UART1_RxTail;
static volatile unsigned char UART1_LastRxError;
#endif


SIGNAL(UART0_RECEIVE_INTERRUPT)
/*************************************************************************
Function: UART Receive Complete interrupt
Purpose:  called when the UART has received a character
**************************************************************************/
{
    unsigned char tmphead;
    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

    /* calculate buffer index */ 
    tmphead = ( UART_RxHead + 1) & UART_RX_BUFFER_MASK;

    if ( tmphead == UART_RxTail ) {
        /* error: receive buffer overflow */
        lastRxError = UART_BUFFER_OVERFLOW >> 8;
    } else {
        /* store new index */
        UART_RxHead = tmphead;
        /* store received data in buffer */
        UART_RxBuf[tmphead] = data;
    }
    UART_LastRxError = lastRxError;
}


SIGNAL(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;
    UART_RxHead = 0;
    UART_RxTail = 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_getc()
Purpose:  return byte from ringbuffer  
Returns:  lower byte:  received byte from ringbuffer
          higher byte: last receive error
**************************************************************************/
unsigned int uart_getc(void)
{
    unsigned char tmptail;
    unsigned char data;

    if ( UART_RxHead == UART_RxTail ) {
        return UART_NO_DATA;   /* no data available */
    }

    /* calculate /store buffer index */
    tmptail = (UART_RxTail + 1) & UART_RX_BUFFER_MASK;
    UART_RxTail = tmptail; 

    /* get data from receive buffer */
    data = UART_RxBuf[tmptail];

    return (UART_LastRxError << 8) + data;

}/* uart_getc */


/*************************************************************************
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);

}/* uart_putc */


/*************************************************************************
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 */


/*
 * these functions are only for ATmegas with two USART
 */
#if defined( ATMEGA_USART1 )

SIGNAL(UART1_RECEIVE_INTERRUPT)
/*************************************************************************
Function: UART1 Receive Complete interrupt
Purpose:  called when the UART1 has received a character
**************************************************************************/
{
    unsigned char tmphead;
    unsigned char data;
    unsigned char usr;
    unsigned char lastRxError;

    /* read UART status register and UART data register */ 
    usr  = UART1_STATUS;
    data = UART1_DATA;

    /* */
    lastRxError = (usr & (_BV(FE1)|_BV(DOR1)) );

    /* calculate buffer index */ 
    tmphead = ( UART1_RxHead + 1) & UART_RX_BUFFER_MASK;

    if ( tmphead == UART1_RxTail ) {
        /* error: receive buffer overflow */
        lastRxError = UART_BUFFER_OVERFLOW >> 8;
    } else {
        /* store new index */
        UART1_RxHead = tmphead;
        /* store received data in buffer */
        UART1_RxBuf[tmphead] = data;
    }
    UART1_LastRxError = lastRxError;
}


SIGNAL(UART1_TRANSMIT_INTERRUPT)
/*************************************************************************
Function: UART1 Data Register Empty interrupt
Purpose:  called when the UART1 is ready to transmit the next byte
**************************************************************************/
{
    unsigned char tmptail;

    if ( UART1_TxHead != UART1_TxTail) {
        /* calculate and store new buffer index */
        tmptail = (UART1_TxTail + 1) & UART_TX_BUFFER_MASK;
        UART1_TxTail = tmptail;
        /* get one byte from buffer and write it to UART */
        UART1_DATA = UART1_TxBuf[tmptail];  /* start transmission */
    } else {
        /* tx buffer empty, disable UDRE interrupt */
        UART1_CONTROL &= ~_BV(UART1_UDRIE);
    }
}


/*************************************************************************
Function: uart1_init()
Purpose:  initialize UART1 and set baudrate
Input:    baudrate using macro UART_BAUD_SELECT()
Returns:  none
**************************************************************************/
void uart1_init(unsigned int baudrate)
{
    UART1_TxHead = 0;
    UART1_TxTail = 0;
    UART1_RxHead = 0;
    UART1_RxTail = 0;

    /* Set baud rate */
    if ( baudrate & 0x8000 ) {
        UART1_STATUS = (1<<U2X1);  //Enable 2x speed 
        baudrate &= ~0x8000;
    }
    UBRR1H = (unsigned char)(baudrate>>8);
    UBRR1L = (unsigned char) baudrate;

    /* Enable USART receiver and transmitter and receive complete interrupt */
    UART1_CONTROL = _BV(RXCIE1)|(1<<RXEN1)|(1<<TXEN1);
    
    /* Set frame format: asynchronous, 8data, no parity, 1stop bit */   
#ifdef URSEL1
    UCSR1C = (1<<URSEL1)|(3<<UCSZ10);
#else
    UCSR1C = (3<<UCSZ10);
#endif

}/* uart1_init */


/*************************************************************************
Function: uart1_getc()
Purpose:  return byte from ringbuffer  
Returns:  lower byte:  received byte from ringbuffer
          higher byte: last receive error
**************************************************************************/
unsigned int uart1_getc(void)
{
    unsigned char tmptail;
    unsigned char data;

    if ( UART1_RxHead == UART1_RxTail ) {
        return UART_NO_DATA;   /* no data available */
    }

    /* calculate /store buffer index */
    tmptail = (UART1_RxTail + 1) & UART_RX_BUFFER_MASK;
    UART1_RxTail = tmptail; 

    /* get data from receive buffer */
    data = UART1_RxBuf[tmptail];

    return (UART1_LastRxError << 8) + data;

}/* uart1_getc */


/*************************************************************************
Function: uart1_putc()
Purpose:  write byte to ringbuffer for transmitting via UART
Input:    byte to be transmitted
Returns:  none          
**************************************************************************/
void uart1_putc(unsigned char data)
{
    unsigned char tmphead;

    tmphead  = (UART1_TxHead + 1) & UART_TX_BUFFER_MASK;

    while ( tmphead == UART1_TxTail ) {
        ;/* wait for free space in buffer */
    }

    UART1_TxBuf[tmphead] = data;
    UART1_TxHead = tmphead;

    /* enable UDRE interrupt */
    UART1_CONTROL |= _BV(UART1_UDRIE);

}/* uart1_putc */


/*************************************************************************
Function: uart1_puts()
Purpose:  transmit string to UART1
Input:    string to be transmitted
Returns:  none          
**************************************************************************/
void uart1_puts(const char *s )
{
    while ( *s ) {
        uart1_putc(*s++);
    }

}/* uart1_puts */


/*************************************************************************
Function: uart1_puts_p()
Purpose:  transmit string from program memory to UART1
Input:    program memory string to be transmitted
Returns:  none
**************************************************************************/
void uart1_puts_p(const char *progmem_s )
{
    register char c;

    while ( ( c = pgm_read_byte(progmem_s++) ) ) {
        uart1_putc(c);
    }

}/* uart1_puts_p */


#endif /* uart1 */