关于延时的问题

只看该作者 · 2017-7-25 10:16

AVR的延时是如何计算的，下面的代码是外部晶振3.6864M的，我现在变成12M，cpuMega8
/*************************************************************************
delay loop for small accurate delays: 16-bit counter, 4 cycles/loop
*************************************************************************/
static inline void _delayFourCycles(unsigned int __count)
{
if ( __count == 0 )
      __asm__ __volatile__( "rjmp 1f\n 1:" ); // 2 cycles
else
      __asm__ __volatile__ (
         "1: sbiw %0,1" "\n\t"
         "brne 1b"                            // 4 cycles/loop
         : "=w" (__count)
         : "0" (__count)
         );
}

/*************************************************************************
delay for a minimum of <us> microseconds
the number of loops is calculated at compile-time from MCU clock frequency
*************************************************************************/

#define delay(us)  _delayFourCycles( ( ( 1*(F_CPU/4000) )*us)/1000 )

需要修改吗？比如原来delay(1500),现在要改成多少？