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Codelock
About the device in general
The 'codelock' is a typical keyboard lock application. The primary target is to activate the output
relay using a code. The input device is a keyboard (usually 12 keys) and the output
is an electrical impulse to the relay. This circuit is very popular and can be used in many applications
such as security systems, identification or control of different devices. The code can be stored
into the memory (if any exists) or hard coded into the circuit. The code can be easy to change
if memory is used to store it.
The system can be built with micro-processor or only with logic circuits.
Application
Here is presented an application where 12 keys keyboard is used to enter 4 digits code.
If the code is the same as the stored into the memory the relay is activated.
The code can be changed at anytime. The application can control upto 3 different devices
by entering different codes.
The system is based on microprocessor pic16f84.
The device can be used to unlock different doors from one place instead of using 3 similar devices for
each door.
Sound signal is included during the operation with the keyboard. A small LED is indicating change in
the code.
The application consumes 40mA max. The processor goes to sleep mode if the keyboard is not used for
some time, which
saves energy by reducing the total consumption to microamperes.
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