Mega128的串口通讯程序

＃i nclude <iom128v.h>＃i nclude <macros.h>＃i nclude "uart.h"/* USART Buffer Defines */#define USART_RX_BUFFER_SIZE 16 /* 1,2,4,8,16,32,64,128 or 256bytes */#define USART_RX_BUFFER_MASK ( USART_RX_BUFFER_SIZE - 1 )#define USART_TX_BUFFER_SIZE 16 /* 1,2,4,8,16,32,64,128 or 256bytes */#define USART_TX_BUFFER_MASK ( USART_TX_BUFFER_SIZE - 1 )#if ( USART_RX_BUFFER_SIZE & USART_RX_BUFFER_MASK )#error RX buffer size is not a power of 2#endif/* Static Variables */static unsigned char USART_RxBuf[USART_RX_BUFFER_SIZE];static volatile unsigned char USART_RxHead;static volatile unsigned char USART_RxTail;static unsigned char USART_TxBuf[USART_TX_BUFFER_SIZE];static volatile unsigned char USART_TxHead;static volatile unsigned char USART_TxTail;/* 串口初始化 */void InitUSART(INT8U  baudrate){INT8U x;UBRR0L = baudrate;UCSR0B = ( (1<<RXCIE0) | (1<<RXEN0) | (1<<TXEN0) );/*RXCompleteInterrupt Enable, Receiver Enable and Transmitter Enable*/x = 0; /* flush receive buffer */USART_RxTail = x;USART_RxHead = x;USART_TxTail = x;USART_TxHead = x;}/* 接收中断 */void USART_RX_interrupt( void ){unsigned char data;unsigned char tmphead;data = UDR0; /* read the received data */tmphead = ( USART_RxHead + 1 ) & USART_RX_BUFFER_MASK;/*calculatebuffer index */USART_RxHead = tmphead; /* store new index */if ( tmphead == USART_RxTail ){return;/* ERROR! Receive buffer overflow, you can useflux cortorl */}USART_RxBuf[tmphead] = data; /* store received data in buffer*/}/* 发送中断 */void USART_TX_interrupt( void ){unsigned char tmptail;if ( USART_TxHead != USART_TxTail )/* check if all data istransmitted */{tmptail = ( USART_TxTail + 1 ) & USART_TX_BUFFER_MASK;/*calculate buffer index */USART_TxTail = tmptail; /* store new index */UDR0 = USART_TxBuf[tmptail]; /* start transmition */}else{UCSR0B &= ~(1<<UDRIE0); /* disable UDRE interrupt */}}/* 读取数据函数 */unsigned char ReceiveByte( void ){unsigned char tmptail;while ( USART_RxHead == USART_RxTail ) /* wait for incommingdata */;tmptail = ( USART_RxTail + 1 ) & USART_RX_BUFFER_MASK;/*calculatebuffer index */USART_RxTail = tmptail; /* store new index */return USART_RxBuf[tmptail]; /* return data */}/* 发送数据函数 */void TransmitByte( unsigned char data ){unsigned char tmphead;tmphead = ( USART_TxHead + 1 ) & USART_TX_BUFFER_MASK; /*calculatebuffer index */while ( tmphead == USART_TxTail )/* wait for free space inbuffer */;USART_TxBuf[tmphead] = data; /* store data in buffer */USART_TxHead = tmphead; /* store new index */UCSR0B |= (1<<UDRIE0); /* enable UDRE interrupt */}/* 查询是否有数据 */unsigned char DataInReceiveBuffer( void ){return ( USART_RxHead != USART_RxTail ); /* return 0 (FALSE)if thereceive buffer is empty */}/* 中断中只做很少的事情，通常我是在接收中断中post一个信号量，触发别的任务读数据*/