MC9S12HY64 (板子是DEMO9S12HY64） 上的休眠 按键唤醒例程。 板子得电后，LED闪烁20下后，休眠。 按SW3键后，MCU唤醒，LED闪烁20下后，休眠。 如此重复。(MC9S12HY64 (board is DEMO9S12HY64) on the sleep button wake routine. After the board gets power, the LED blinks 20 times and then goes to sleep. After