Pls i need advice on a suitable sensor to detect if a door has been locked from outside?

What i have seen around is basically to detect if a door has been locked. But i need a system in which a microcontroller would receive a signal only if the door has been locked from outside (only one side). Would really appreciate your help.

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rickharris2 years ago

It may be easier to detect if the key is close by (RFID) AND the door is locked.

IF the key hangs by the door over an RFID detector AND the door is locked then your inside .

IF the door is locked BUT the Key is not detected then the door was locked from the outside and the key removed.

You could detect the locked door with something as simple as a microswitch on the latch bolt.

iceng2 years ago

This $8 sensor can do it.

But you cant Lurk and make it work.

Goto answer....

seandogue2 years ago

Where have you seen around?

And why do you need such a device? Frankly, it sounds a bit questionable to me.

What kind of lock ?

iceng2 years ago

First need to know if in can be locked from the inside too ?

And is the outside lock a physical key ?

I am asking if the lock is a tumbler key lock ?