单片机密码锁源程序和原理图：用4*3的键盘组成0~9的数字键及确认键、删除键；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“—”，当密码位数输入完毕按下确认键时，对输入的密码和设定的初始密码进行比较，若密码正确，则开锁，此时P3.0口的LED（即黄灯）亮一秒作为提示；若密码不正确，禁止输入3秒种，同时发出报警声。初始密码为8位。

增加功能：利用外部中断0和1分别实现复位和密码修改功能

-SCM locks source code and schematics: 4* 3 keypad with numeric keys and the Enter key consisting of 0 to 9, the delete key　with 8 digital tube display circuit message composition, when a password, only " -"　When the password digits have been entered, press enter, and set the initial password password input comparison, if the password is correct, then unlock, then P3.0 port LED (ie yellow) light for one second as a reminder　 if the password is incorrect, prohibit the importation 3 seconds, an alarm sounds at the same time. The initial password is eight. New feature: external interrupts 0 and 1 respectively, to achieve a reset and password change function