很久就在用这个功能，一直很好用。现在整理了一下，把这个软件帖出来，希望对大家有用处。
可以用于232或485通讯。通过预编译选择。
以下uart.h:
#ifndef _uart_h
#define _uart_h
#include "avr/io.h"
#define TURE 1
#define FALSE 0
#define RS485MODE TURE //TURE:rs485 FALSE:rs232
#define BAUDRATE 51 //baud rate
#define UART_buffer_size 32 //must 1,2,4,8,16,32,64,128 or 256 bytes
#if (RS485MODE == TURE)
#define TX_EN PIND2
#define TX_DDR DDRD
#define TX_PORT PORTD
#define RS_485_port_init() TX_DDR |= (1<<TX_EN)
#define RS_485_send() TX_PORT |= (1<<TX_EN) //RS485 enable
#define RS_485_receive() TX_PORT &= ~(1<<TX_EN) //RS485 disable
#endif
//--------------------------------------------------------------------------------------
//UART Buffer Defines
//--------------------------------------------------------------------------------------
#define UART_RX_BUFFER_SIZE UART_buffer_size
#define UART_RX_BUFFER_MASK ( UART_RX_BUFFER_SIZE - 1 )
#define UART_TX_BUFFER_SIZE UART_buffer_size
#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
//--------------------------------------------------------------------------------------
//unsigned char ReceiveByte( void )
//Parameters: none
//Function: Read a byte from uart
//Notice: None
//Created: 2005-3-1 , By zsmbj
//--------------------------------------------------------------------------------------
unsigned char ReceiveByte( void );
//--------------------------------------------------------------------------------------
//void TransmitByte( unsigned char data )
//Parameters:
//Function: write a byte to uart
//Notice: None
//Created: 2005-3-1 , By zsmbj
//--------------------------------------------------------------------------------------
void TransmitByte( unsigned char data );
//--------------------------------------------------------------------------------------
//unsigned char DataInReceiveBuffer( void )
//Parameters:
//Function: if have a uart data then return 1
//Notice: None
//Created: 2005-3-1 , By zsmbj
//--------------------------------------------------------------------------------------
unsigned char DataInReceiveBuffer( void );
#endif
以下uart.c:
#include "uart.h"
#include "avr/interrupt.h"
/**********************************************************************/
/* These are the global variables */
/**********************************************************************/
//UART related buffers and variables
unsigned char UART_RxBuf[UART_RX_BUFFER_SIZE];
volatile unsigned char UART_RxHead;
volatile unsigned char UART_RxTail;
unsigned char UART_TxBuf[UART_TX_BUFFER_SIZE];
volatile unsigned char UART_TxHead;
volatile unsigned char UART_TxTail;
/**********************************************************************/
/* UART subroutine. */
/**********************************************************************/
/* initialize UART */
void init_UART( void )
{
UBRRL = BAUDRATE; //set the baud rate
UBRRH = 0;
//enable UART receiver and transmitter, and receive interrupt
UCSRA = 0;
UCSRB = ( (1<<RXCIE) | (1<<RXEN) | (1<<TXEN) );
UCSRC = ( (1<<URSEL) | (1<<UCSZ1) | (1<<UCSZ0) );
UART_RxTail = 0; //flush receive buffer
UART_RxHead = 0;
UART_TxTail = 0;
UART_TxHead = 0;
#if (RS485MODE == TURE)
RS_485_port_init();
RS_485_receive();
#endif
}
//--------------------------------------------------------------------------------------
//SIGNAL (SIG_UART_RECV)
//Parameters: none
//Function: uart rxd interrupt
//Notice: None
//Created: 2005-3-1 , By zsmbj
//--------------------------------------------------------------------------------------
SIGNAL (SIG_UART_RECV)
{
unsigned char data;
unsigned char tmphead;
data = UDR; //read the received data
tmphead = ( UART_RxHead + 1 ) & UART_RX_BUFFER_MASK; //calculate buffer index
UART_RxHead = tmphead; //store new index
if ( tmphead == UART_RxTail ) //ERROR! Receive buffer overflow
{
}
UART_RxBuf[tmphead] = data; //store received data in buffer
}
//--------------------------------------------------------------------------------------
//SIGNAL (SIG_UART_DATA)
//Parameters: none
//Function: uart udre interrupt
//Notice: None
//Created: 2005-3-1 , By zsmbj
//--------------------------------------------------------------------------------------
SIGNAL (SIG_UART_DATA)
{
unsigned char tmptail;
if ( UART_TxHead != UART_TxTail ) //check if all data is transmitted
{
tmptail = ( UART_TxTail + 1 ) & UART_TX_BUFFER_MASK;//calculate buffer index
UART_TxTail = tmptail; //store new index
UDR = UART_TxBuf[tmptail]; //start transmition
}
else
{
UCSRB &= ~(1<<UDRIE); //disable UDRE interrupt
#if (RS485MODE == TURE)
UCSRB |= (1<<TXCIE); //enable TXCIE interrupt
#endif
}
}
//--------------------------------------------------------------------------------------
//SIGNAL (SIG_UART_TRANS)
//Parameters: none
//Function: uart txd interrupt
//Notice: None
//Created: 2005-3-1 , By zsmbj
//--------------------------------------------------------------------------------------
#if (RS485MODE == TURE)
SIGNAL (SIG_UART_TRANS)
{
RS_485_receive(); //close rs485 send data.
UCSRB &= ~(1<<TXCIE); //disable TXCIE interrupt
}
#endif
//--------------------------------------------------------------------------------------
//unsigned char ReceiveByte( void )
//Parameters: none
//Function: Read a byte from uart
//Notice: None
//Created: 2005-3-1 , By zsmbj
//--------------------------------------------------------------------------------------
unsigned char ReceiveByte( void )
{
unsigned char tmptail;
while ( UART_RxHead == UART_RxTail ) //wait for incomming data
;
tmptail = ( UART_RxTail + 1 ) & UART_RX_BUFFER_MASK; //calculate buffer index
UART_RxTail = tmptail; //store new index
return UART_RxBuf[tmptail]; //return data
}
//--------------------------------------------------------------------------------------
//void TransmitByte( unsigned char data )
//Parameters:
//Function: write a byte to uart
//Notice: None
//Created: 2005-3-1 , By zsmbj
//--------------------------------------------------------------------------------------
void TransmitByte( unsigned char data )
{
unsigned char tmphead;
tmphead = ( UART_TxHead + 1 ) & UART_TX_BUFFER_MASK; //calculate buffer index
while ( tmphead == UART_TxTail ) //wait for free space in buffer
;
UART_TxBuf[tmphead] = data; //store data in buffer
UART_TxHead = tmphead; //store new index
#if (RS485MODE == TURE)
RS_485_send(); //open rs485 send data mode if send data ok then close
#endif
UCSRB |= (1<<UDRIE); //enable UDRE interrupt
}
//--------------------------------------------------------------------------------------
//unsigned char DataInReceiveBuffer( void )
//Parameters:
//Function: if have a uart data then return 1
//Notice: None
//Created: 2005-3-1 , By zsmbj
//--------------------------------------------------------------------------------------
unsigned char DataInReceiveBuffer( void )
{
return ( UART_RxHead != UART_RxTail ); //return 0 (FALSE) if the receive buffer is empty
}
//end of program
以下main.c：测试用
#include "uart.h"
int main(void)
{
init_UART();
//if received a uart byte then send it
if( DataInReceiveBuffer() )
{
TransmitByte( ReceiveByte() );
}
}
以上程序在winavr20060421下编译通过，单片机atmega8515。
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