Anyone else here working on a better xEM access controller?

I don’t have an implant yet but intend on ordering an xEM soon. That said, I have been looking at all of the solutions for interfacing with it. I mostly want to use it to start my motorcycles and open garage doors, nothing too crazy, I just don’t want keys or remotes.

I ordered the V1 xEM AC and as most know, they are quite antiquated, very mysterious and lack some commonly desired functionality. I have now seen the new V2 AC and it seems like an improvement but still doesn’t seem like what the people truly want.

Over this past weekend I decided that I should actually use my degree and start looking into building the solution that would fit many peoples needs including my own. I would love to start a community driven open source project and would love to hear what people want in an access control device and also what is also already in progress.

My idea is to use an EM4095 front end chip and something like an atmega328 or attiny84 for running the access control code. Leaning towards the 328 because can you really have too much I/O? Maybe even an ESP32 for wifi capability, For me a cylindrical antenna coil is a must and due to the fact that nobody makes them, they will have to be hand made at first.

Things I would personally like to implement in this project are:

  • 12v power
  • waterproof
  • mode selection with rotary dip switch
  • Immobilizer mode: tap once to energize relay, tap once more to de-energize
  • immobilizer mode with button disable: tap once to energize relay, press button to de-energize relay
  • starter switch mode: relay energized when tag is present
  • door mode: tap for pulse with configurable pulse time with rotary dip switch, door release button
  • audible feedback
  • jumper for configuring master tags
  • jumper for selecting between EM and HID (for all of the people I envy that have a simple work access control)(for this I would need some help figuring out the modulation protocol)

That’s honestly what I can come up with on my own. Any Suggestions?


I guess my question is, if we are designing a access control module why build a inherently insecure LF system? I’d be much more interested in a HF reader that couples well with X form factor implants. By default it could be UID based and you could flash firmware for securely interacting with the xDF2 for example. The only reason I have LF implants is so I can use legacy systems not because I want to continue to use them personally.


All this and more! Im going to bed. But lf vs hf is a big question as well as why use the uid not the best for security :thinking: been toying with the idea of using some sort of key system which would be cool.

Toggling outputs is something alot of people want i was working on the toggleator but thats been sidelined due to work life commitments. Scan tag and it alternates between 2 oputputs (outputs are simply optocouplers to allow you to press a button)

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Or maybe a modular system is what we are after?

A reader tuned for X form factor implants + a controller module that handles the relay config etc?

Also @mcarter14777 welcome :smiley:

I thought you where going to bed @Devilclarke :stuck_out_tongue: sleep != replying

sure we have talked about that before, something that basically allows you to plug in off the shelf wiegand readers would be cool to.

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Yeah but Wiegand takes us back to insecure legacy UID based tech… Which there is plenty of, no real need to put significant effort into making new stuff. Just grab something like this:

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From what I have seen of the V2 AC’s on AliExpress there is a 3 pin header for wiegand input. Might be the same with the ones offered on DT.

Thanks for the warm welcome! And since this is my first endeavour into the RF world, I was thinking of taking things slow with UID reading technologies first. And namely 125khz first.


Yeah. I think focusing on UID is fine for now. But why 125kHz? I can’t see any reasons to stick to it? The implants require special tools to interact with vs a mobile phones for HF. There are more options of HF implants. If we wanted to put effort into security features the option is there with HF but not with LF. Also there is the old AC and the V2 but nothing for HF (that’s doesn’t require the end user to code a microcontroller). Just seems like a more significant hole in the market, all the exciting new stuff is HF.

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That makes perfect sense, and I did notice this market gap.
And strangely, I have found it easier to find more open source resources for HF than LF. But with closed source hardware it is the other way around.
I’ll have to look deeper into the specifics of HF and weigh all of my front end chip options.


Whatever route you go down, very interested to see where it goes!


A dual frequency access controller also wouldn’t be a terrible idea. HID does it with their iClass SE readers. It would just have to be jumper selectable for all of the NExT/two chips in the same spot people.


You wouldn’t even need a jumper if you handled it correctly. The HF / LF tags don’t get mixed up, it’s just readers not handling both at the same time particularly well that causes issues afaik.