/*-----------------------------------------------------------------------
延時函數
系統時鐘：4M
-----------------------------------------------------------------------*/
void delay_1us(void)                 //1us延時函數
  {
   asm("nop");
  }

void delay_nus(unsigned int n)       //N us延時函數
  {
   unsigned int i=0;
   for (i=0;i<n;i++)
   delay_1us();
  }
  
void delay_1ms(void)                 //1ms延時函數
  {
   unsigned int i;
   for (i=0;i<1140;i++);
  }
  
void delay_nms(unsigned int n)       //N ms延時函數
  {
   unsigned int i=0;
   for (i=0;i<n;i++)
   delay_1ms();
  }