1.zs一次按键，先上升沿后下降沿

代码说明：

  cc2530双边沿触发中断，一次按键产生两次中断，按键第一次按下为下降沿触发，第二次按下为上升沿触发。(CC2530 bilateral edge triggers interruption, one button produces two interruptions, the first button is triggered by the falling edge, the second button is triggered by the rising edge.)