请教M64访问16C554A的问题,谢谢

只看该作者 · 2007-5-15 00:37

大家好,我做了一个小的系统,其中用到了16C554A,但是怎样也发送不出数据.下面附上一段相关的程序和

原理图,请各位费心,谢谢!
我没有用中断,用的是16C554A的FIFO POLLED MODE.初始化之后,直接发数据.
CPU为,MEGA64,16M晶振.

#define TL16c554A_Base ((volatile unsigned char*) 0x8000)
#define TL16c554B_Base ((volatile unsigned char*) 0xa000)
#define TL16c554C_Base ((volatile unsigned char*) 0xc000)
#define TL16c554D_Base ((volatile unsigned char*) 0xe000)

#define RBR 0
#define THR 0
#define DLL 0
#define DLM 1
#define IER 1
#define IIR 2
#define FCR 2
#define LCR 3
#define MCR 4
#define LSR 5
#define MSR 6

SREG=0x80;                     //Enable all interrupt.
MCUCR=0xc0;                    //Enable external memory extending.
XMCRA=0x02;                    //Disable Bus holding
XMCRB=0x00;                    //Disble Bus release.
XDIV=0x00;                     //Disable system clk divide.

void Init_UART(void)
   {
     TL16c554_RST=0;
     _delay_ms(1);
     TL16c554_RST=1;
     _delay_ms(1);
     TL16c554_RST=0;
     *(TL16c554A_Base+FCR)=0x0f;           // FIFO polled mode .
     *(TL16c554A_Base+LCR)=0x80;
     *(TL16c554A_Base+DLL)=0x06;
     *(TL16c554A_Base+DLM)=0x00;
     *(TL16c554A_Base+MCR)=0x00;
     *(TL16c554A_Base+LCR)=0x03;
     *(TL16c554A_Base+IER)=0x00;

   }

void Tx_UART(void)
   {
     unsigned char temp=0,i;

     temp=*(TL16c554A_Base+LSR);

     //Serial_TX(temp);
     if(temp&0x60==0x60)  //读取LSR的值为0x60,表示发送寄存器和发送移位寄存器空.
        {          //但是还是发不出数据.(通过串口发送LSR的值,可以确定为0x60)

         *(TL16c554A_Base)=0xff;
         _delay_ms(20);

        }
   }
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