#include <reg51.h>
#include <string.h>

#define INBUF_LEN 	4   		//數據長度
#define STARTBYTE	0x24		//
#define MYADD		0xE3		//MOTOR MODULE ADD = 0xE3	, 0xE2 - LDDRIVER, 0xE1 - PZT DRIVER

unsigned char inbuf1[INBUF_LEN];
unsigned char checksum,count3;
bit           read_flag=0;

void init_serialcomm(void)
{
    SCON  = 0x50;       //SCON: serail mode 1, 8-bit UART, enable ucvr 
    TMOD |= 0x20;       //TMOD: timer 1, mode 2, 8-bit reload 
    PCON |= 0x80;       //SMOD=1; 

    TH1   = 0xF4;       //Baud:4800  fosc=11.0592MHz 
    IE   |= 0x90;       //Enable Serial Interrupt 
    TR1   = 1;          // timer 1 run 
 //   TI=1; 
}

//向串口發送一個字符 
void send_char_com(unsigned char ch)  
{
    SBUF=ch;
    while(TI==0);
    TI=0;
}

//向串口發送一個字符串，strlen為該字符串長度 
void send_string_com(unsigned char *str,unsigned int strlen)
{
    unsigned int k=0;
    do 
    {
        send_char_com(*(str + k));
        k++;
    } while(k < strlen);
}


//串口接收中斷函數 
void serial () interrupt 4 using 3 
{
unsigned char ch;

	ES = 0;

	if(RI && read_flag==0)
    {
		RI = 0;
	 	ch = SBUF;
		if( count3 ==0)	   		//startbyte
		{
			if(ch == STARTBYTE)
				inbuf1[count3++] = ch;
		}
		else 
			if(count3 == 1)		//add
			{
			 	if(ch == MYADD)
					inbuf1[count3++] = ch;
				else
					count3 = 0;
			}
			else
			{
				inbuf1[count3++] = ch;
				
				if(count3 == 4)
				{
			 		count3 =0;
					read_flag = 1;
				}
			}
	 }
	 ES = 1;

}


main()
{
    init_serialcomm();  //初始化串口 
	send_string_com("TEST",4);
    P0 &=~(1<<5);
    while(1)
    {
          if(read_flag)  //如果取數標志已置位，就將讀到的數從串口發出 
          {
               read_flag=0; //取數標志清0 
               send_string_com(inbuf1,INBUF_LEN);
          }
    }
}