关于AVR单片机的问题5

wangxd5429 · 发表于 2014-12-3 10:12:44

各位高手，小弟正在基于AVR开发一款智能小车，遇到“串口接收字符串错误”，调试了一下，发现当屏蔽了端口B后，可以正常显示,对端口B赋值后，无法正常显示。请教其中的原因。谢谢。部分代码如下：

void main(void)
{
    int counter = 0;
   int i;
   int stop_count = 0;

   MCUCSR |= BIT(7);
   MCUCSR |= BIT(7);

   vInitEeprom();
   uart0_init();
    init_devices();
    EECR |= BIT(EERIE);
   DUTY1=50;
    DUTY2=50;
    LCD_write_string(0,0,dis1);
    LCD_write_string(0,1,"SPACE:");
   memcpy (ControlMsg , "stop" , 4);
   addr = 1;

   while(1)
    {
      //str_send (Xunji);
      if (Xunji == 1)
      {
          //rcv_new = 0;
          //str_send ('x');
          stop_count = 0;
          forward();
         //delay_nms(10);
          if(L_XJ == 0 || R_XJ == 0)
           {
              break;
          }
      }
      else if (Xunji == 0)
      {
          //rcv_new = 0;
         //str_send ('c');
          if (stop_count == 0)
         {
             //str_send ('c');
             stop();
            stop_count++;
         }
      }
   }

   while(1)
    {
       if (Xunji == 1)
      {
          //rcv_new = 0;
          stop_count = 0;
          switch (PINB&0x03)
           {
               case 0x03:
                 DUTY1 = 35;
                 DUTY2 = 35;
                 //str_send ('a');
                 forward();
                 break;
              case 0x00:
                 DUTY1 = 35;
                 DUTY2 = 35;
                 //str_send ('b');
                 forward();
                 break;
              case 0x02:

                 for (i = 0 ; i < 5 ; i++)
                 {
                    if ((PINB&0x03) == 0x02)
                    {
                        counter++;
                    }
                    else if ((counter >= 0)&&(counter < 5)&&((PINB&0x03) == 0x03))
                    {
                        break;
                    }

                 }

                 if (counter == 5)
               {
                    counter = 0;
                     DUTY1 = 40;
                    //str_send ('c');
                    left_slow();
                 }
                 else if (counter != 5)
                 {
                     counter = 0;

                    DUTY1 = 40;
                    DUTY2 = 40;
                    //str_send ('d');
                    left();
                 }

                 break;
              case 0x01:

                 for (i = 0 ; i < 5 ; i++)
                 {
                     if ((PINB&0x03) == 0x01)
                    {
                        counter++;
                    }
                    else if ((counter >= 0)&&(counter < 5)&&((PINB&0x03) == 0x03))
                    {
                        break;
                    }
                 }

                 if (counter == 5)
                 {
                    counter = 0;

                     DUTY2 = 40;
                    //str_send ('e');
                    right_slow();

                 }
                 else if (counter != 5)
                 {
                    counter = 0;

                    DUTY2 = 40;
                    DUTY1 = 40;
                    //str_send ('f');
                    right();
                 }
                break;
             default:
                 break;
           }
      }
      else if (Xunji == 0)
      {
          //rcv_new = 0;
          if (stop_count == 0)
          {
             stop();
            stop_count++;
          }
      }

      start_SB();
   }
}

#pragma interrupt_handler usart0_isr:12
void usart0_isr(void)
{
    static unsigned char i;

    UCSRB &= ~BIT(7);
   ControlMsg = UDR;
   i++;
   if (i == 4)
   {
       i = 0;
      LCD_write_char(7,1,ControlMsg[0]);
       LCD_write_char(8,1,ControlMsg[1]);
       LCD_write_char(9,1,ControlMsg[2]);
       LCD_write_char(10,1,ControlMsg[3]);

      if (memcmp (ControlMsg , "star" , 4) == 0)
       {
           Xunji = 1;
       }
       else if (memcmp (ControlMsg , "stop" , 4) == 0)
       {
           Xunji = 0;
       }
       else
       {
           ;
       }
   }
   UCSRB |= BIT(7);
}