//中斷方式

SysTick_Config(72000000/5);

void SysTick_Handler(void)

{

?GPIO_WriteBit( GPIOA, GPIO_Pin_0,!GPIO_ReadOutputDataBit( GPIOA, GPIO_Pin_0));

}

非中斷方式

//1s? 72000000? ? 1us? 72

void delay_us(uint32_t us)

{

SysTick->CTRL = 0;? ? // Disable SysTick

SysTick->LOAD = 72*us-1; // Count from 255 to 0 (256 cycles)

SysTick->VAL = 0;? ? ?// Clear current value as well as count flag

SysTick->CTRL = 5;? ? // Enable SysTick timer with processor clock

while ((SysTick->CTRL & 0x00010000)==0);// Wait until count flag is set

SysTick->CTRL = 0; // Disable SysTick

}

//1s? 72000000? ? 1ms? 72000

void delay_ms(uint32_t ms)

{

while(ms--)

{

SysTick->CTRL = 0;? ? // Disable SysTick

SysTick->LOAD = 72000-1; // 計數(shù)值

SysTick->VAL = 0;? ? ?// Clear current value as well as count flag

SysTick->CTRL = 5;? ? // Enable SysTick timer with processor clock

while ((SysTick->CTRL & 0x00010000)==0);// Wait until count flag is set

SysTick->CTRL = 0; // Disable SysTick

}

}

void delay_s(uint32_t s)

{

while(s--)

{

delay_ms(1000);

}

}