How to lock Door by 4x4 Keypad

[teemo55]

I want to lock the doors with electromagnetic encrypted with 4x4 Keypad.
Using FPGA (VHDL), but I do not know how to make the board aware that the press would go.
-------- Password 4 digits.
Let me point out that I or anyone could have a preview.

* Thank you.

 

[arishsu]

Hi,
If you are using EM keypad, you need the coding circuitry for that I think. But if you are going to implement it in FPGA you can use simple push button keys and connect them to a mux and AND gate Circuit. A 4:1 mux can be used for 4 digit code. AND gate is for detecting if any key is pressed or not. Select line of the mux should come from a controller which you have to design. Initially set select line to 0. Your first digit of the code should be connected to input 0, Second digit to input 1 and s on. After each key pressed select line should change its value. You can implement all in FPGA and you only have to connect key pad and lock driving motors as hardware.