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。

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

Formed with 8-bit digital tube display circuit prompts when a password, only show "8.", When finished press Enter to confirm the password digit key, enter the password on the password and compare, if the password is correct , then the door opened, light emitting diode LED used here as a prompt for a second, also issued "Ding Dong" sound　If the password is not correct, against key input for 3 seconds, also issued a "tick, tick" sound alarm　if in 3 seconds still pressing the button, then the ban button for 3 seconds to be re-importation ban.