用4×4组成0－9数字键及确认键。

用8位数码管组成显示电路提示信息，当输入密码时，只显示“8.”，当密码位数输入完毕按下确认键时，对输入的密码与设定的密码进行比较，若密码正确，则门开，此处用LED发光二极管亮一秒钟做为提示，同时发出“叮咚”声；若密码不正确，禁止按键输入3秒，同时发出“嘀、嘀”报警声；若在3秒之内仍有按键按下，则禁止按键输入3秒被重新禁止。

-4 × 4 with the composition of the number keys 0-9 and confirm key.

With 8-bit digital tube display circuit message, when the input password, only shows "8.", When the median enter password press the confirm button when finished to set the password with the password for comparison, if the password correct, then the door opened here with a bright LED light-emitting diodes as a matter of seconds suggests that at the same time issued a "ding dong" sound　if the password is not correct to prohibit the importation of key three seconds, at the same time issued a "嘀,嘀" alarm sound　if there are still three seconds of pressing the button, the button to prohibit re-importation ban on three seconds.