Cortex-M3 Core之指令

1. __DSB()指令:

Data Synchronization Barrier, This function acts as a special kind of Data Memory Barrier.  It completes when all explicit memory accesses before this instruction complete.

執行個體(Timer的時鐘源頻率低於MCU主頻)：

void TIMER0_IRQHandler(void)
{
     /* Clear interrupt source */
     timer->IFC = TIMER_IFC_OF;
     /* Flushing instructions to make sure that the interrupt is not re-triggered*/
     /* This may be required when the peripheral clock is slower than the core */
     __DSB(); //需要等待RAM訪問完成，防止重複觸發中斷。

     /* Stopping timer */
     timer->CMD = TIMER_CMD_STOP;

}