Latency function error: volatile and volatile

Latency function error: volatile and volatile

An inexplicable error. Latency caused by the use of javasick.

The initialization is like this:

// SysTick Configuration

SysTick_CLKSourceConfig (SysTick_CLKSource_HCLK_Div8 );

If (SysTick_Config (SystemCoreClock/1000) // enable clock interruption and configure Clock.

{

While (1 );

}

Then:

// Latency function. 1 nTime is equivalent to 1 ms.

Static uint32_t TimingDelay;

Void Delay (_ IO uint32_t nTime)

{

TimingDelay = nTime;

While (TimingDelay! = 0 );

}

Void TimingDelay_Decrement (void)

{

If (TimingDelay! = 0x00)

{

TimingDelay --;

}

}

Everything is normal, and there is no problem with the code.

But something is wrong today.

While (TimingDelay! = 0 );

When TimingDelay is reduced to 0, it still does not exit. Delay failed. Something inexplicable.

Then I discussed the problem in the group and found the problem.

This is optimized by the compiler.

Define static uint32_t TimingDelay;

Change to static _ IO uint32_t TimingDelay = 0;

That is, static volatile uint32_t TimingDelay = 0;

That's all.

Volatile is used as a command keyword to ensure that this command is not omitted due to compiler optimization and requires that the value be read directly each time.