serial.c

一个简单的单片机串口通信的小程序

//收发缓冲区长度
#define LenTxBuf        2000    //Don't too small,because it will cause display abnormal.
#define LenRxBuf        50

#define MaxLenStr       100     /*buf[MaxLenStr+1] for '\0'*/

#define	TABNum          4       //TAB键移动长度






#include <reg51.h>




unsigned char TxBuf[LenTxBuf],RxBuf[LenRxBuf];//收发缓冲区实体
unsigned char *inTxBuf,*outTxBuf,*inRxBuf,*outRxBuf;//收发缓冲区读写指针

bit TIflag=1;//Note:It must be 1.

void InitSerial()  // reentrant//串口初始化
{
        TMOD=TMOD&0x0F;
        TMOD=TMOD|0x20;
        TL1=0xFD,TH1=0xFD;//19200 , 22.1184MHz
        SCON=0x50;PCON=0x00;
        TR1=1;
}

void InitSerialBuffer(void)   // reentrant//串口缓冲区初始化
{
        inTxBuf=TxBuf;outTxBuf=TxBuf;
        inRxBuf=RxBuf;outRxBuf=RxBuf;
//      ES=1;
        EA=1;
}

void serial(void)  interrupt 4
{   //串口中断服务子程序
        unsigned char *t;

        if(TI){
                TI=0;
                if(inTxBuf==outTxBuf) {TIflag=1;return;}//TxBuf Empty
                SBUF=*outTxBuf; outTxBuf++;
                if(outTxBuf==TxBuf+LenTxBuf) outTxBuf=TxBuf;	
        }
        if(RI){
                RI=0;
                t=inRxBuf;t++;
                if(t==RxBuf+LenRxBuf) t=RxBuf;
                if(t==outRxBuf) return;                 //RxBuf Full
                *inRxBuf=SBUF;
                inRxBuf=t;
        }
}

bit yygetch(unsigned char *ch) //reentrant//从串口缓冲区读1字节数据
{
        //ES=0;        
        if(inRxBuf==outRxBuf) {ES=1;return 0;}          //RxBuf Empty
        *ch=*outRxBuf;  outRxBuf++;
        if(outRxBuf==RxBuf+LenRxBuf) outRxBuf=RxBuf;
        //ES=1;        
        return 1;
}

void PrintChar(unsigned char ch) //reentrant//显示字符
{
        unsigned char *t;

        //ES=0;        
       if(TIflag){		
                TIflag=0;
                TI=1;
        }
        t=inTxBuf;t++;
        if(t==TxBuf+LenTxBuf) t=TxBuf;
        if(t==outTxBuf) {/*ES=1;*/return;}                  //TxBuf Full
        *inTxBuf=ch;
        inTxBuf=t;
        //ES=1;        
}

void PrintCh(unsigned char ch) //reentrant//内部使用，不建议用户看到。
{
        if(ch>=0&&ch<=9) ch=ch+'0';
        else ch=ch+'A'-10;
        PrintChar(ch);
}

void insidePrintByte(unsigned char Byte) //reentrant//内部使用，以十六进制格式显示1个字节数据
{
        unsigned char c;
        c=Byte;
        c=c>>4;        
        PrintCh(c);
        c=Byte;c=c&0x0F;PrintCh(c);        
}

void PrintByte(unsigned char Byte) //reentrant//以十六进制格式显示1个字节数据
{
        EA=0;        
        insidePrintByte(Byte);                
        EA=1;
}

void insidePrintWord(unsigned int Word) //reentrant//内部使用，以十六进制格式显示1个字数据
{	        
        insidePrintByte(Word>>8);
        insidePrintByte(Word&0xFF);                        
}

void PrintWord(unsigned int Word) //reentrant//以十六进制格式显示1个字数据
{	
        EA=0;
        insidePrintWord(Word);
        EA=1;
}

void PrintLong(unsigned long LongWord) //reentrant//以十六进制格式显示1个长字数据
{
        EA=0;
        insidePrintWord(LongWord>>16);
        insidePrintWord(LongWord&0xFFFF);
        EA=1;
}

void PrintStr(unsigned char *str) //reentrant//显示字符串
{
        int i;
        unsigned char j;
        unsigned char ch;
	
        EA=0;
        for(i=0;i<MaxLenStr;i++){
                ch=*(str+i);
                if(ch=='\0') break;
                else if(ch=='\n'){PrintChar(10);PrintChar(13);} 
                else if(ch=='\t'){
                        for(j=0;j<TABNum;j++)
                                PrintChar(' ');
                }
                else PrintChar(ch);
        }
        EA=1;
}

void clrscr() //reentrant//清屏
{        
        PrintStr("\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n");//25个回车换行清屏幕。
}


main()
{
	unsigned char ch;

	InitSerial();
	InitSerialBuffer();
	while(1){
		PrintStr("\n");
		PrintByte(90);PrintStr(" ");
		PrintWord(90);PrintStr(" ");
		PrintLong(90);PrintStr(" ");
		PrintChar('y');PrintChar(' ');//千万别写成双引号，否则打印0（乱字符）。
		PrintStr("\nHello!\nI'm YangYi.\n");
		PrintStr("Press any key to continue...");
		while(!yygetch(&ch));
	}
}