4个LED与pb6按键程序，pb6按下的0次，led全灭，1次，led2亮；2次，led3亮；3次，led4亮；4次，led5亮；5次，全灭。如此循环。-The of four LED pb6 key procedures, pb6 press 0, led all off, once, led2 light 2, led3 light 3, led4 light 4, led5 light five times, all of