Hi! I have an idea that optic lock encoder and decoder with arduino. For example door lock. I will have a LED for the key and door lock will use something like photodiode and decode the light comes thru. Maybe LED blink morse code or some pattern that arduino can detect and open the lock. Any help appreciated. Thanks.
It would be pretty easy to have the an IR remote decoder in the door and use a IR remote or an IR LED that sends IR remote codes for the key. The IRremote library can do both the decode and send functions.
If you want it to provide reasonable security you will need a pseudo-random code that changes each time and a lock that won't accept the same code twice.