Access controllers, antennas, and scanning to pc

[Pfisher1102]

I have yet to get an implant, but am set on a NExT and will likely order it within a few days. I see that for many projects, people tend to use DT’s xEM access controller. I would like, however, to make my own. As i feel like it will save money and provide some experience. I have no idea what antennas are compatible with the xEM though. And I dont see many places where it’s mentioned. I believe an arduino would be needed to use what the antenna reads? Id also like to be able to look at, and make changes to the data on the chip. How would this be done? Is this even necessary for the xEM? I know I can do loads like that with the xNT side, but what about the xEM?

[amal]

To start, what you are calling an antenna isn’t like any other antenna you’ve ever worked with. Read this first;

Frankenstein the xEM access controller for proxmark proxlf

To further clarify why borrowing an antenna probably won’t work; Normal radios like cell phones, wifi, etc. are all “EF” emitters… they emit waves of electrical potential across the electric field. Those types of antennas are simply unshielded conductors, and they are “tuned” to a frequency by adjusting their length to best match a harmonic of the wavelength of the radio frequency being transmitted (or received). That means if you take one 2.4ghz antenna from a wifi router and attach it to anot…

You will have to build a matching L/C tank circuit … an inductor and capacitor pair that resonate at 125kHz… so you’ll likely have to either build / wind it yourself, or buy one of a known inductance and adjust your capacitance to match it properly. So, if you end up buying a 125kHz reader module with antenna already on board, and you want to trade out that antenna for another one, you’ll have to be sure the inductance of the new antenna matches that of the old one or it won’t work.

@Pfisher1102

Id also like to be able to look at, and make changes to the data on the chip.

you should definitely look into a proxmark3 rdv4 with proxLF antenna… it’s the defacto standard device for doing any RFID research or tinkering.

@Pfisher1102

Is this even necessary for the xEM?

not really… we ship all T5577 chips pre-configured with EM41xx emulated chip configurations, which is the absolute most common chip type read by basically every 125kHz OEM reader module.

[Pfisher1102]

So, what I’m hearing is that unless I have a good understandong of circuitry, your xEM access controller is the best to use?

[Pilgrimsmaster]

It will also be the cheapest and fastest.
Plug and play option vs. less learnings.
So “best” is subjective.

[amal]

Yes it’s all subjective… if your goal is to be cheaper and easier then the access controller is the best option. If you want to take on a learning curve and probably have a fair bit of frustration, but come out on the other side with some deeper knowledge about 125kHz RFID then I’d say build your own. Either way, we’d all be here to support you. @Pilgrimsmaster is my defacto forum king at this point.

[Pfisher1102]

I may do that as a later project then. Once I get my implant I plan on making my car completely key-less.
Are there any other things I’d be able to do bring able to write into the xEM using a PC? If it’s all set when you get it why would anyone write something new on it. Other than making a copy of something else.

[Pfisher1102]

It turns out I was asking the wrong question. As i was greatly confused what the xEM access controller was, and its limitations. What would best low frequency reader be to hook up to an arduino?