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 and confirm the composition of the number keys 0-9 keys. With 8-bit digital tubes display circuit prompts when a password, only show " 8." , When finished press Enter to confirm the password digit key, the input The password to compare with the password, if the password is correct, then the door opened, light emitting diode LED used here as a second prompt, 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 there within 3 seconds press the button, then the ban button for 3 seconds to be re-importation ban.