dma

DMA例程

//============================================================	
//         C异步写程序块：从模块读到数据从串口发出
//============================================================
	#include <reg51.h>
	#include "intrins.h"
	#include "absacc.h"
	#include <stdio.h>
	void  delay(unsigned int k ); 
//--------------------------------------------

	sbit DMAING 	= P2^0;
	sbit DMADIR 	= P2^1;   
	sbit FIFOEMPTY 	= P2^2;
	sbit FIFOFULL 	= P2^3;
	sbit DMACS  	= P3^4;
	sbit DMAOE 	    = P2^5;
	sbit PTKEND 	= P2^6;
	sbit DMAWR  	= P3^6;

	sbit DMARD  	= P3^7;


//**********************************************************************
//         主程序开始
//**********************************************************************
	void main(void)
	{
	    unsigned    char   pdata  *y;	  //Y为外部变量指针，用以残产生RD 脉冲
		unsigned 	char  i;
	    TMOD = 0x20;  SCON = 0x40;  PCON = 0x00;  TL1 = 0xFD;  TH1 = 0xFD;		 	//波特率9600
		EA = 0;  SP = 0x70;  TR1 = 1; DMACS = 0;  PTKEND = 1;  DMAOE = 1;
		for(;;)
		{   
		    DMAOE = 0;	 
		    if (  (DMAING == 1) && (DMADIR == 0) && (FIFOEMPTY == 1))
			  {
			     y = 0xff;														   
				 ACC = *y; 
				 SBUF = ACC;
				 delay( 2 );			   //延时1MS，等待1个字节发送完成
				}
		}
	  }
   void  delay(unsigned int k ) 			
          {
		unsigned  int i,j;
		      for(i=0; i<k; i++)
			    {
				   for(j=0; j<60; j++)
				    {;}
				}
			}