NFC Lock/Unlock with Arduino

This is going to be kind of a messy thread, as it’s my first “build log”, first time messing with Arduino, and therefore keeps evolving.

I can’t use the xAC with my NExT, as the xAConly works with EM4200 formatted chips, and I switched mine to Wiegand for work.

I’m using an arduino Nano, a PN532 NFC reader, and a dual channel relay.

I’ve got everything wired and coded to run off the car’s power, so I don’t need a external power source, and the dual channel relay allows me to both lock and unlock the car with one reader and microcontroller.

This is what I ended up with.

I’ve got a couple pictures of my attaching it to my vehicle that I’ll upload when I finish wiring it all in (Should be today/tomorrow).

I have concerns with draining the car’s battery, so I’ve ordered a capacitave touch sensor I plan on adding in the next week or so in order to take advantage of the sleep mode function of the arduino without having to add an extra step in the unlock proccess. I’ll update the thread as I figure out how ti make that work through the sideview mirror’s plastic I’ve opted to mount the reader inside of.

As this is my first project, I’m open to advise, and also would like to thank @Pilgrimsmaster and @Satur9 for all the help they’ve provided so far.


Cool, can’t wait to see the project! Any reason you whent for a touch sensor rather than a button? Or is it purely aesthetic? (Not wanting another hole in the car)

Partially aesthetic, but mostly since the reader is on the outside of the car, I figured a tactile button may be a problem (People knowing there’s something there, etc) as well as I’d be able to wake it and scan the chip in one step by running my hand across, rather than having to wake it before scanning.

That and it was $8 for a pack of 10, and my daughter was quite upset the other day when she saw I had a “magic” hand and she didn’t. Figured I could use the rest to do some projects for her.


Perfect! I like the

My son described it like that to the first time :joy:


I hope that was a typo and you meant projects WITH her! Of course, age and interest depending, but her showing an interest in that sort of thing is a great way to get her started with her own Arduino and learning simple code! The critical thinking skills it teaches alone are invaluable, let alone the cool factor!


I would love to, but I don’t get to see her too often. Her ma does absolutely nothing with her, so most of our time together is trying to make sure she doesn’t fall too far behind developmentally. We do a lot of projects together, but they mostly centered around learning how to count to 5/10 or communication. I show her what I’m working on and try to teach her when she shows interest though.


Sorry to hear that man, but sounds like you’re doing great things with her. Maybe not one for now, but could be a great birthday present down the line then.

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No worries, just trying to do what I can with what I’ve got. Wasn’t trying to vent about personal issues or anything.

I’m really excited to see what she’s into as she gets older, and absolutely plan on getting her involved with as much as possible once she gets there.


The story of every good parent ever!

Anyway, cant wait to see the project in completion! What micro are you using?


So atmega328


I saw that but wondered if he was going to embed (custom board/solution) or leave it as a nano.

Maybe thats how I should have phrased the question.

I wanted to, but don’t currently have the means to. My long term-plan is to build a shield to program SMD AtMega chips, and make my own PCBs.

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Awesome, always love to see people progressing and learning! I really like the pro micro board based around a atmega32u4 nice little board with native USB.

In the first post you mention you xEM has a wieland do you mean its got a HID ID? If so have you had a look at arduino HID readers they do exist.

Nah, the xEM Access controller, I mistyped, sorry.

The xAC will only accept EM tags, but I’ve got the xEM side of my NExT with a Wiegand UID on it.

And I’m always about learning. Saturn mentioned the possibility of using a low voltage cutoff for the microcontroller, but I felt there was more room to learn about arduino/C++ with a interrupt switch.

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Updating because I said I would.

I have everything on the car wired to run off an external power source right now, but everything works. I got my switches in the mail today, so I’ll probably spend this weekend learning the code and wiring it up to run entirely off the car.

Once I do that, I can make a Video of how I ran it all on the car so nothing’s visible. The wiring is an absolute mess, but that was more my learning how to translate wiring diagrams to reality.


Awesome, looking forward to it

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So, uh. I fell off the face of the earth.

I want to replace the DuPont connectors I used with something that won’t snap off pins in the female side, but other than that, it’s fully functional

What kind of car/ year model?!

It’s an old '98 Camry. figure I’d rather break a $600 dollar car learning something new than an expensive one

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I used to have a 97’ Camry. Oldest car I ever owned, also only car I ever sold :laughing:
(Every other car I drove into the ground or donated)