Author Options:

Parallax RFID reader Door Lock Answered

I bought a parallax RFID reader from Radio Shack and was wondering how I could turn it into a door lock?  I don't have an Arduino or an interface to connect it to the computer.  I have some code from their site but i don't know how to put it on.  Tell me what I need and what I need to do.

1 Replies

orksecurityBest Answer (author)2010-06-13

Have you looked at the Instructables under the "Related" column at right? You need an electrically-controlled lock, either purchased or homebrew. (Basically, a solenoid or motor that will extend or retract a lockbolt -- or that will unlatch a knob so you can extend or retract the bolt, which takes much less power but is a more complicated mechanical design.) You need some form of computer to read the output of the RFID reader, notice when an RFID tag has been presented, and decide whether this particular tag is one of those authorized to open this door, and to activate the latch for an appropriate length of time if so. A microcontroller -- Arduino or other -- would be the low-cost compact solution, but if you were willing to tie a larger computer into this circuitry it could serve the purpose. You need software which will run on that computer to implement those "listen for and respond to the RFID reader" rules, along with implementing some way to tell it to add or remove tags from the authorized list. You need to know enough about interfacing to computers to connect the RFID reader to the computer's input, connect the computer's output to the lock mechanism (through appropriate drivers that can handle the current it requires, since the computer almost certainly can't drive it directly), and to get that software installed and debugged. You need a reliable power supply for all of this, so you aren't locked out during a blackout. (Or you need an alternative way to get in, eg with a key. Or you need to be able to supply emergency backup power from outside, without jeopardizing security.) If you think this is starting to sound like a nontrivial project, you're right. It's not huge, but it isn't exactly something I'd suggest to a beginner. My recommendation would be to either take it in small pieces -- learn how to work with the reader, then figure out a workable lock mechanism, then figure out what kind of computer you're going to use between these. Once again: Check the existing instructables about locking projects.

Select as Best AnswerUndo Best Answer