说明：  no intro
(IO port registers: the direction to select register PxDIR, output register PxOUT of input register PxIN the IO port internal pull-up or pull-down resistor enable register PxREN, the IO port function select register PxSEL and PxSEL2 IO port interrupt enable register PXIeThe interrupt edge select register PXIES, IO port interrupt flag register PxIFG.     3, all IO with interrupt all the P1 port public an interrupt vector, the P2 port public an interrupt vector. To use an interrupt when the interrupt entry, but also to determine which IO port interrupt in the end, the judgment method can determine the level of each IO port.       4 Clear interrupt Logo PxIFG require software can also be set in software, the software triggers an interrupt. Note: setting up the PxIESx according to PxINx may cause the corresponding PxIFGx set (specifically, see the User s Guide), so after you initialize the IO port interrupt, official use the IO interrupt before the first corresponding)