Using AT89C52 to Design Disord

The password keyboard as a kind of input device that is essential to bank and otherfinancial departments, it must have high credibility, safety, and the function of keeping secret.
Disorder keyboard is a developed kind on the basis of the traditional password keyboard, whichincreased some new functions and characteristics, for example, there is LED on the surface ofthe keys, and the numbers displayed on the keys are random, also a certain angle of view isrestricted. Outside of a certain angle, the number LED displayed on the keyboard is impossibleto be seen. Even other people can see the keys that the customer pressed, but because when thecustomer finished inputting the password, the key numbers will be rearranged again, so, thecustomer unnecessarily worried about that other people would take his password.