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 off. So the cycle.