中断方式.c

8250扩展串口的单片机C51例程和相关资料。

/* CONSOLE.C -- serial I/O code */
/* Initialize serial port hardware and variables */

#include "serint.h"

void SerInitialize()             //串口初始化函数
{
    SerFlags = 0; 
    FlagTransIdle = 1;           //声明可以发送
    FlagCvtInCR = 1;             /* want to turn CRs into LFs */
    RR_iHead = RR_iTail = RR_cLev = RR_cMax = 0;
    TR_iHead = TR_iTail = TR_cLev = TR_cMax = 0;
    UnGotCh = -1;                //EOF
 
/* 设置定时器1,用来生产串口的波特率 */

   TCON &= 0x3F;          /* clear run & interrupt flags */
   TMOD &= 0x0F;          /* flush existing Timer 1 setup */
   TMOD |= 0x20;          /* flush existing Timer 1 setup */

   SCON = 0x50;           /* flush existing Timer 1 setup */
   PCON |= 0x00; 
   TH1 = TL1 = T1RELOAD & 0x00FF;     /* flush existing Timer 1 setup */
   TR1 = 1;               /* start the timer */
   ES = 1;                /* enable serial interrupts */
}

/*---------------------------------------------------------------------------*/
/* Serial console interrupt handler */
/* If transmitter output is disabled, we fake trans interrupts until empty */

void SerInt() interrupt 4    //串口中断处理函数
{
    if(RI)                          //如果是接收中断
    {                 
        if(RR_cLev)                 //如果接收缓冲计数器不为零
        { 
            RRing[RR_iHead] = SBUF; //接收数据,并写入接收缓冲区
            RR_iHead++;             //头指针++
            RR_cLev++;              //接收计数器++
            if(RR_iHead == INRINGSIZE) RR_iHead = 0;     //如果缓冲区满,则头指针回0
        }
        RI = 0;                     //清中断标志
    }

    if(TI)                          //如果是发送中断
    {                  
        if(TR_cLev)                 //如果计数器不为零(有数据发送)
        {
            SBUF = TRing[TR_iTail]; //将发送缓冲区内数据写入串口
            TR_cLev--;              //计数器--
            TR_iTail++;             //尾指针指向下一个数据
            if(TR_iTail==OUTRINGSIZE) TR_iTail = 0;   //如果缓冲区内的数据都已发送完,尾指针赋初值(0)
        } 
        else                        //如果缓冲区内无数据
        {
            FlagTransIdle = 1;      //声明缓冲区空
        }
        TI = 0;                     //清中断标志
    }
}

/*---------------------------------------------------------------------------*/
/* Send character to console */
/* Can strip LFs, in which case you get CR instead of LF/CR */

int putch(int TransChar)             //输出1个字符
{
    putc(TransChar);                 /* if not LF, handle normally */
    if(TransChar == '\n')            //如果输出换行符
    {
    	putc('\r');                  //
    }
}

int putc(int TransChar)
{
    while(TR_cLev >= OUTRINGSIZE);     /* wait for space in ring */
    ES = 0;                            //关中断
    TRing[TR_iHead] = TransChar;     /* point to char slot */
    TR_iHead++;                      /* tick counter & index */
    TR_cLev++;
    
    if(TR_iHead == OUTRINGSIZE) TR_iHead = 0;    //如果缓冲区满,指针循环
    
    if(FlagTransIdle)                   //如果可以发送
    {
        FlagTransIdle = 0;              //声明正在发送
        TI = 1;                         //置发送中断标志
    }

    ES = 1;                             //开中断
    return(TransChar);
}

/*---------------------------------------------------------------------------*/
/* 查看是否接收到数据,并将缓冲区内数据长度返回 */

int chkch() 
{
    return(RR_cLev);                 /* tack on current level */
}

/*---------------------------------------------------------------------------*/
/* Wait for the serial transmitter to go idle */
/* If the transmitter is disabled, that's considered to be the same thing */

void SerWaitOutDone() 
{
    while (TR_cLev);                 //等待发送缓冲区空
    while(!FlagTransIdle);           //等待最后1个数据发送完
} 

/*---------------------------------------------------------------------------*/
/* Flush the input buffer */
/* Returns number of chars flushed */


int SerFlushIn() 
{
    ES = 0;                         /* turn off serial interrupts */
    RR_iTail = 0;                   /* reset ring variables */
    RR_iHead = 0;
    RR_cLev = 0;
    ES = 1;                         /* turn on serial interrupts */
}

/*---------------------------------------------------------------------------*/
/* Get character from console */
/* CRs turn into LFs unless we're not doing that... */

int getch() 
{
    int RetVal;
    
    ES = 0;                             //关中断
    if(RR_cLev)                         //如果接收缓冲区内有数据
    {      
        RetVal = RRing[RR_iTail];
        if(RetVal == '\r') RetVal = '\n';    //转换换行符
        RR_iTail++;        /* tick size index & counter */
        RR_cLev--;
        if(RR_iTail == INRINGSIZE) RR_iTail = 0; /* hit end of array yet? */
    } 
    else 
    {
    	RetVal = -1;
    }
    ES = 1;
    return(RetVal);
}

/*---------------------------------------------------------------------------*/
/* Send string to console */
/* putstr(char *pString); */
/* The ?putstr entry point has *pString in DPTR */

int putstr (char *pstring)
{
    while(*pstring)         //如果不是空字符
    {
        putch(*pstring);
        pstring++;               /* continue... */
    }
}