Alarme residencial em vhdl

VHDL itself cannot give alarm. So there is some information missing...

What kind of sensors?
What function has the switch?
What should happen with the siren?
And then more detailed:
Why VHDL?
What target (fpga/cpld)?
Is there a clock on the system?
How is the power supply?
Is this homework for school?



BTW: Pls. try to communicate english. Very few people speak and 
understand Portugese.