//文件名：	WRS485T.c 程序用UART1外擴MAX485實現RS-485通信，運行前將TX1和P00 短//          接，RX1和P01短接，當接收到一個數據后，再將接收到的數據送出。
#include <c8051f020.h>                 /*SFR定義*/
#include <intrins.h>
#define SYSCLK       11059200          /*系統頻率*/
#define BAUDRATE     9600              /*波特率*/
sbit	BUZ = P3^5;
sbit	P32 = P3^2;						/*接收/發送控制*/
void SYSCLK_Init (void);
void PORT_Init (void);
void UART1_Init (void);
void UART1_ISR (void);
void LCD_Init(void);
bit	ReceiveBit;
unsigned char temp;
float  FFF;	
int    ff;
/*延時子程序*/
void delay(unsigned int m)
{
	unsigned int n;
	n=0;
	while(n < m)
	{n++;}
	return;
}
void main (void) {
    WDTCN = 0xde;                       /*關看門狗*/
   WDTCN = 0xad;
   ReceiveBit=0;
   SYSCLK_Init ();                     /*初始化系統時鐘*/
   PORT_Init ();                       /*初始化I/O口*/
   LCD_Init();
   UART1_Init ();                      /*初始化UART1*/
   P32 = 1;								/*發送模式*/
    P7 = 0x54;                          /*顯示T>*/
  	P6 = 0x0c;
	P6 = 0x0d;
	delay(300);				    /*延時*/
	P7 = 0x3e; 
	P6 = 0x0c;
	P6 = 0x0d; 
    delay(300);				    /*延時*/
			SBUF1 = 0x61;                /*發送字符 a*/			
			while(SCON1&0x02==0);		/*發送中斷模式是否產生*/
			SCON1 = SCON1&0xfd;			/*清發送中斷標志*/
			delay(3000);				    /*延時*/
            	P7 = 0x61;              /*顯示發送的字符*/
               	P6 = 0x0c;
	            P6 = 0x0d;
				SBUF1 = 0x62;                /*發送字符 b*/			
			while(SCON1&0x02==0);		/*發送中斷模式是否產生*/
			SCON1 = SCON1&0xfd;			/*清發送中斷標志*/
			delay(3000);				    /*延時*/
            	P7 = 0x62;              /*顯示發送的字符*/
               	P6 = 0x0c;
	            P6 = 0x0d;
				SBUF1 = 0x63;                /*發送字符 c*/			
			while(SCON1&0x02==0);		/*發送中斷模式是否產生*/
			SCON1 = SCON1&0xfd;			/*清發送中斷標志*/
			delay(3000);				    /*延時*/
            	P7 = 0x63;              /*顯示發送的字符*/
               	P6 = 0x0c;
	            P6 = 0x0d;
				SBUF1 = 0x64;            /*發送字符 d*/			
			while(SCON1&0x02==0);		/*發送中斷模式是否產生*/
			SCON1 = SCON1&0xfd;			/*清發送中斷標志*/
			delay(3000);				    /*延時*/
            	P7 = 0x64;              /*顯示發送的字符*/
               	P6 = 0x0c;
	            P6 = 0x0d;
		while(1){	
		_nop_();
	}
}
void SYSCLK_Init (void)
{
   int i;                              /*延時計數器*/
   OSCXCN = 0x67;                      /*開始外部22.1184MHz晶體*/
   for (i=0; i < 256; i++) ;           /*等待外部晶體起振穩定*/
   while (!(OSCXCN & 0x80)) ;          /*查詢標志位*/
   OSCICN = 0x88;                      /*用外部晶體頻率作為系統時鐘，并使能時鐘丟失檢測*/
}
void PORT_Init (void)
{
   XBR2    |= 0x44;                    /*使能UART1和交叉開關，弱上拉*/
   P0MDOUT |= 0x01;                    /*使能TX1推挽輸出*/
   P3MDOUT |= 0x20;                    /*P3.5驅動蜂鳴器*/
   P74OUT  = 0xff;      
}
void UART1_Init (void)
{
   SCON1  = 0x50;                      /*SCON1:模式1, 8-bitUART,使能RX*/
   TMOD   = 0x20;                      /*TMOD: 定時器1,定時器2, 8位重載*/  
   //TH1=0xb8;                           /*設置定時器1作為波特率的重載值*/
   TH1=-(SYSCLK/BAUDRATE/16);
   TR1    = 1;                         /*開定時器1*/
   CKCON |= 0x10;                      /*定時器1用系統時鐘作為時基*/
   PCON  |= 0x10;                      /*SMOD1 = 1,波特率加倍*/
   //EIE2  |= 0x40;                    /*使能UART1中斷*/
}
void LCD_Init(void)
{
	unsigned int x;
	P6 = 0x09;
	for(x=0;x<50000;x++);
   //P7 = 0x30;				/*一行顯示*/
   P7 = 0x38;				/*兩行顯示*/
   P6 = 0x08;
   P6 = 0x09; 
   for(x=0;x<1000;x++);
   P7 = 0x0e;				/*開顯示，開光標，字符不閃爍*/
   P6 = 0x08;
   P6 = 0x09;
   for(x=0;x<1000;x++);
   P7= 0x06;				/*I/D=1,AC自動增1；S=0,整體顯示不移動*/
   P6 = 0x08;
   P6 = 0x09;
   for(x=0;x<5000;x++);
   P7 = 0x01;				/*清除DDRAM,置AC=0*/
   P6 = 0x08;
   P6 = 0x09; 
   for(x=0;x<5000;x++);
}