[求助] 诡异的串口无法发送

zfeng45 2013-4-21 22:38 楼主

写的熔丝位匹配程序，可以进入if判断语句，就是不往串口寄存器UDR0写入数据0x55，求高人解答，感激涕零！

#include
#include

#define F_CPU 12000000UL
#define baud 9600

int fuse_check();
void uart0_init(void);
void delay_1ms();

void main()
{

   uart0_init();


if(fuse_check()==0)
         {
      while(1)
                  {
                        while( !(UCSR0A & (1<
                           UDR0 = 0x55;       //发送数据0x55

                           //delay_1ms();
                  }

         }

      //else

         // UDR0 = 0x66;       //发送数据0x66


}

int fuse_check()
{


      unsigned int a=0,b=1;

      // 读取熔丝位低字节
      asm("LDI R30,0x00");       //赋0x0000给Z指针
      asm("LDI R31,0x00");
      SPMCSR = 0x09;                      //置位SPMCSR寄存器
      asm("LPM");                //读取低字节数据给R0
      asm("STS 0x002E,R0");  //复制R0数据给PORTE


      if(PORTE==0x0C)             //低字节匹配判断
               {

                     //读取熔丝位高字节
                     asm("LDI R30,0x03");       //赋0x0003给Z指针
                     asm("LDI R31,0x00");
                     SPMCSR=0x09;                      //置位SPMCSR寄存器
                     asm("LPM");                //读取低字节数据给R0
                     asm("STS 0x002E,R0"); //复制R0数据给PORTE


                     if(PORTE==0x00)                      //高字节匹配判断
                     {

                                    //读取熔丝位扩展字节
                                       asm("LDI R30,0x02");       //赋0x0002给Z指针
                                       asm("LDI R31,0x00");
                                       SPMCSR=0x09;                      //置位SPMCSR寄存器
                                       asm("LPM");                //读取低字节数据给R0
                                    asm("STS 0x002E,R0"); //复制R0数据给PORTE


                                       if(PORTE==0x4A)                      //扩展字节匹配判断
                                       {
                              b=0;
                                             return b;
                                       }
                                    else
                                       {
                                             a=1;
                                             return a;
                                       }

                        }
                  else
                        {
                              a=1;
                              return a;
                        }
            }
      else
      {
               a=1;
               return a;
      }


}

//UART0初始化
void uart0_init(void)
{
      UCSR0A = 0x00; //设置波特率时无效
UCSR0B = 0x00;
UCSR0C = 0x00;

UBRR0L =(F_CPU/baud/8-1)%256;
UBRR0H =(F_CPU/baud/8-1)/256;

UCSR0C = (1<
UCSR0B = (1<

}