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.