刚好最近一个产品要产生这种声音,觉得有些意思,把它贴出来,感兴趣的不妨玩一下. /* chip:pic16c54 OSC:HS  FREQUENCY :20MHz WDT:DISABLE */ #include "pic.h" #define beep_out RA2    //音效输出 char tmr_buff; char cycle_buff; char cycle_set; int change_set; int change_count; bit change_flag; void main(void) {TRISA=0X0;     PORTA=0;     OPTION=4;     cycle_buff=52;     cycle_set=100;     change_set=196;     TMR0=0;     while(1)     {             if(TMR0==0)             {TMR0=(cycle_set-1)^0XFF;                 beep_out=!beep_out;                 change_count+=cycle_set;                 if(change_count>change_set)                 {change_count-=change_set;                     if(change_flag)                     {if(++cycle_set>195)                         {change_flag=0;                         }                     }                 else                     {if(--cycle_set<52)                         {change_flag=1;                         }                     }                 }             }     } }    

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