uart.h

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/*! \file uart.h \brief UART driver with buffer support. */
//*****************************************************************************
//
// File Name    : 'uart.h'
// Title        : UART driver with buffer support
// Author       : Pascal Stang - Copyright (C) 2000-2002
// Created      : 11/22/2000
// Revised      : 02/01/2004
// Version      : 1.3
// Target MCU   : ATMEL AVR Series
// Editor Tabs  : 4
//
// This code is distributed under the GNU Public License
//      which can be found at http://www.gnu.org/licenses/gpl.txt
//
/// \ingroup driver_avr
/// \defgroup uart UART Driver/Function Library (uart.c)
/// \code #include "uart.h" \endcode
/// \par Overview
///     This library provides both buffered and unbuffered transmit and receive
///     functions for the AVR processor UART.  Buffered access means that the
///     UART can transmit and receive data in the "background", while your code
///     continues executing.  Also included are functions to initialize the
///     UART, set the baud rate, flush the buffers, and check buffer status.
///
/// \note   For full text output functionality, you may wish to use the rprintf
///     functions along with this driver.
///
/// \par About UART operations
///     Most Atmel AVR-series processors contain one or more hardware UARTs
///     (aka, serial ports).  UART serial ports can communicate with other 
///     serial ports of the same type, like those used on PCs.  In general,
///     UARTs are used to communicate with devices that are RS-232 compatible
///     (RS-232 is a certain kind of serial port).
/// \par
///     By far, the most common use for serial communications on AVR processors
///     is for sending information and data to a PC running a terminal program.
///     Here is an exmaple:
/// \code
/// uartInit();                 // initialize UART (serial port)
/// uartSetBaudRate(9600);      // set UART speed to 9600 baud
/// rprintfInit(uartSendByte);  // configure rprintf to use UART for output
/// rprintf("Hello World\r\n"); // send "hello world" message via serial port
/// \endcode
///
/// \warning The CPU frequency (F_CPU) must be set correctly in \c global.h
///     for the UART library to calculate correct baud rates.  Furthermore,
///     certain CPU frequencies will not produce exact baud rates due to
///     integer frequency division round-off.  See your AVR processor's
///      datasheet for full details.
//
//*****************************************************************************
//@{

#ifndef UART_H
#define UART_H

#include "global.h"
#include "buffer.h"

//! Default uart baud rate.
/// This is the default speed after a uartInit() command,
/// and can be changed by using uartSetBaudRate().
#define UART_DEFAULT_BAUD_RATE  9600

// buffer memory allocation defines
// buffer sizes
#ifndef UART_TX_BUFFER_SIZE
//! Number of bytes for uart transmit buffer.
/// Do not change this value in uart.h, but rather override
/// it with the desired value defined in your project's global.h
#define UART_TX_BUFFER_SIZE     0x0040
#endif
#ifndef UART_RX_BUFFER_SIZE
//! Number of bytes for uart receive buffer.
/// Do not change this value in uart.h, but rather override
/// it with the desired value defined in your project's global.h
#define UART_RX_BUFFER_SIZE     0x0040
#endif

// define this key if you wish to use
// external RAM for the UART buffers
//#define UART_BUFFER_EXTERNAL_RAM
#ifdef UART_BUFFER_EXTERNAL_RAM
    // absolute address of uart buffers
    #define UART_TX_BUFFER_ADDR 0x1000
    #define UART_RX_BUFFER_ADDR 0x1100
#endif

//! Type of interrupt handler to use for uart interrupts.
/// Value may be SIGNAL or INTERRUPT.
/// \warning Do not change unless you know what you're doing.
#ifndef UART_INTERRUPT_HANDLER
#define UART_INTERRUPT_HANDLER  SIGNAL
#endif

// compatibility with most newer processors
#ifdef UCSRB
    #define UCR                 UCSRB
#endif
// compatibility with old Mega processors
#if defined(UBRR) && !defined(UBRRL)
    #define UBRRL               UBRR
#endif
// compatibility with megaXX8 processors
#if defined(__AVR_ATmega88__)   || \
    defined(__AVR_ATmega168__)  || \
    defined(__AVR_ATmega644__)
    #define UDR                 UDR0
    #define UCR                 UCSR0B
    #define RXCIE               RXCIE0
    #define TXCIE               TXCIE0
    #define RXC                 RXC0
    #define TXC                 TXC0
    #define RXEN                RXEN0
    #define TXEN                TXEN0
    #define UBRRL               UBRR0L
    #define UBRRH               UBRR0H
    #define SIG_UART_TRANS      SIG_USART_TRANS
    #define SIG_UART_RECV       SIG_USART_RECV
    #define SIG_UART_DATA       SIG_USART_DATA
#endif
// compatibility with mega169 processors
#if defined(__AVR_ATmega169__)
    #define SIG_UART_TRANS      SIG_USART_TRANS
    #define SIG_UART_RECV       SIG_USART_RECV
    #define SIG_UART_DATA       SIG_USART_DATA
#endif
// compatibility with dual-uart processors
// (if you need to use both uarts, please use the uart2 library)
#if defined(__AVR_ATmega161__)
    #define UDR                 UDR0
    #define UCR                 UCSR0B
    #define UBRRL               UBRR0
    #define SIG_UART_TRANS      SIG_UART0_TRANS
    #define SIG_UART_RECV       SIG_UART0_RECV
    #define SIG_UART_DATA       SIG_UART0_DATA
#endif
#if defined(__AVR_ATmega128__)
#ifdef UART_USE_UART1
    #define UDR                 UDR1
    #define UCR                 UCSR1B
    #define UBRRL               UBRR1L
    #define UBRRH               UBRR1H
    #define SIG_UART_TRANS      SIG_UART1_TRANS
    #define SIG_UART_RECV       SIG_UART1_RECV
    #define SIG_UART_DATA       SIG_UART1_DATA
#else
    #define UDR                 UDR0
    #define UCR                 UCSR0B
    #define UBRRL               UBRR0L
    #define UBRRH               UBRR0H
    #define SIG_UART_TRANS      SIG_UART0_TRANS
    #define SIG_UART_RECV       SIG_UART0_RECV
    #define SIG_UART_DATA       SIG_UART0_DATA
#endif
#endif

// functions

//! Initializes uart.
/// \note   After running this init function, the processor
/// I/O pins that used for uart communications (RXD, TXD)
/// are no long available for general purpose I/O.
void uartInit(void);

//! Initializes transmit and receive buffers.
/// Automatically called from uartInit()
void uartInitBuffers(void);

//! Redirects received data to a user function.
///
void uartSetRxHandler(void (*rx_func)(unsigned char c));

//! Sets the uart baud rate.
/// Argument should be in bits-per-second, like \c uartSetBaudRate(9600);
void uartSetBaudRate(u32 baudrate);

//! Returns pointer to the receive buffer structure.
///
cBuffer* uartGetRxBuffer(void);

//! Returns pointer to the transmit buffer structure.
///
cBuffer* uartGetTxBuffer(void);

//! Sends a single byte over the uart.
/// \note This function waits for the uart to be ready,
/// therefore, consecutive calls to uartSendByte() will
/// go only as fast as the data can be sent over the
/// serial port.
void uartSendByte(u08 data);

//! Gets a single byte from the uart receive buffer.
/// Returns the byte, or -1 if no byte is available (getchar-style).
int uartGetByte(void);

//! Gets a single byte from the uart receive buffer.
/// Function returns TRUE if data was available, FALSE if not.
/// Actual data is returned in variable pointed to by "data".
/// Example usage:
/// \code
/// char myReceivedByte;
/// uartReceiveByte( &myReceivedByte );
/// \endcode
u08 uartReceiveByte(u08* data);

//! Returns TRUE/FALSE if receive buffer is empty/not-empty.
///
u08 uartReceiveBufferIsEmpty(void);

//! Flushes (deletes) all data from receive buffer.
///
void uartFlushReceiveBuffer(void);

//! Add byte to end of uart Tx buffer.
/// Returns TRUE if successful, FALSE if failed (no room left in buffer).
u08 uartAddToTxBuffer(u08 data);

//! Begins transmission of the transmit buffer under interrupt control.
///
void uartSendTxBuffer(void);

//! Sends a block of data via the uart using interrupt control.
/// \param buffer   pointer to data to be sent
/// \param nBytes   length of data (number of bytes to sent)
u08  uartSendBuffer(char *buffer, u16 nBytes);

#endif
//@}

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