PIC16887A单片机RA4接一个按键，要求每按一下按键S1，必须进入中断，在中断中让LED闪亮。即使用时钟中断来实现不带中断的按键实现中断。-PIC16887A SCM RA4 by one button, click the button for each requirement S1, must enter an interrupt, the interrupt enable LED flashes. That the use of clock interrupts to impleme