在Interrupts例程里的延时函数

C:\StellarisWare\boards\ek-lm3s9b90\interrupts\interrupts.c

//*****************************************************************************
//
// Delay for the specified number of seconds. Depending upon the current
// SysTick value, the delay will be between N-1 and N seconds (i.e. N-1 full
// seconds are guaranteed, along with the remainder of the current second).
//
//*****************************************************************************

void
Delay(unsigned long ulSeconds)
{
//
// Loop while there are more seconds to wait.
//
while(ulSeconds–)
{
//
// Wait until the SysTick value is less than 200.
//
while(ROM_SysTickValueGet() > 200)
{
}

//
// Wait until the SysTick value is greater than 200.
// while(ROM_SysTickValueGet() < 200)
{
}
}
}
您好，这里的200是怎么得出来的？能给讲解一下吗？

Yaoming Qin：

您好，这里是Cortex-A处理器的论坛，建议您去MCU的论坛问问这个问题。