设计一个单片机电路，2个按键，1位数码管，4个LED，1个按键按下，

数码管自增1(up)，另一个按键按下，数码管自减1（down）,4个LED

显示数字值。-Design a single-chip circuit, two buttons, a digital control, 4 LED, 1 press the keys, digital control since by 1 (up), another button press, digital control since by 1 (down), 4 LED display numeric values.