红外遥控代码,需要重新配置SysTick的中断优先级为最高，要不然SysTick延时中断抢占不了IO EXTI中断,或者当你用其他定时器做延时的时候，要配置定时器的优先级高于IO EXTI中断的优先级.(Reconfiguration of SysTick interrupts the highest priority, otherwise SysTick delay interrupts cannot preempt IO EXTI interrupts * because the defa