Trouble getting a read with smartphones

ok it must be constant light, not flashing… as when accessing the ACR… thanks for u’re qick reply …

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yes i have nfcTools, NXP TagInf, and Mtools in use… with standard NFC cards it works smoothly with all smartphones

This is the CatS41 tear down, and this :red_circle: is ideally how you should be presenting your xSIID
Interestingly, the NFC antenna is installed in the back cover :large_blue_circle:

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flashing means the xSIID is near enough the NFC antenna coils of the phone to draw power to flash the LED each time the phone probes for NFC tags with its NFC radio… but the alignment of the xSIID is not good enough to power up the LED and the chip also.

You can also try the xFD that you would have received in your order to test your Antenna location and best orientation for reading / writing


You will also see how the NFC works on your phone. eg. My Samsungs throw out about 4-5 low power pulses and then 1 much stronger pulse and repeats.
This is very easy to see with the xFD or Diagnostic Card.

It is also good to confirm that your NFC is functioning correctly / on etc

Yes I use the xFD . that works

another guess from my side is that the chip is maybe implanted a little too deep… hopefully not … hehe

Possibly, coupling is really important.

Using the same orientation you found with the xFD, can you use your phone and press down “hard” and try to read with TagInfo

Me too

Also, what are you trying to do with your xSIID? What is your end goal?
business card?
Rick Rolling?
Smuggling less than 2kB of data across international borders to sell to foreign intelligence agencies etc?

I just tested the xFD again on the cat41… that also does not get a constant signal… probably the shell is just too thick… as I said with the ACR 122U everything works smoothly … maybe i should just buy a new phone :slight_smile:

This is expected. The xFD is just a coil and LED, with no chip. The phone will probe for chips a few times a second, hence the flashing… but if no chip is found it just keeps probing. When a chip is found, the field is turned on constant (like the ACR122U) so the phone can maintain communication with the chip. This probing behavior is a power saving technique used by the phone, but the ACR122U does not use this method, so it just keeps the field on constantly.

So, because the xFD has no chip, it will always flash. The xSIID does have a chip, so the LED will flash when drawing some power, but once the chip has enough power to start communicating, the phone should turn the field on and the LED should remain solid.

Make sense?

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ah yes… of course make sense

Have look through this thread, It will have some images and videos of what to expect, and what to try

it’s just for testing and getting used to it. i actually travel a lot and it’s already practical to have some essential data in my arm. a few small possibilities for remote control are already possible. the end goal would be an additional chip or sensor that i can use for live modulation of sound…

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Have you had any luck yet with a read?

Ahh, Say no more

SO are you aware, that the xSIID has 2 writable sectors ( 0 and 1 ), 0 the first 1k ~ 888 bytes works like the NTAG216 ( such as the xNT and NExT etc ) and you can write to it with TgWriter / NFC Tools etc, the other sector (1) you will need to use NFC shell to write to the chip.

Sounds interesting
Have you seen Roscos

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“SO are you aware, that the xSIID has 2 writable sectors”

Yes, spent a lot of time today setting it up on ubuntu, seems it works …

thanks for the theremin link, didnt know this project … perfect!


Just FYI
Forum tip, Highlight text and select the “quote” button :+1:

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@krtrttx Maybe you could try to extend the range on your phone? :thinking:

Edit: ok, so I had to try this myself.
I have a Sony Xperia 1.the NFC antenna works good, so I initially don’t have a problem, as long as I orient the implant correctly

In any case, I ripped apart a normal tag and placed the coil over my phone, and boy did that make a difference.

I no longer need to “twist” my glassies to get a good read.


Hrmm… I see a 3d-printed phonecase with integrated coil project coming up. :stuck_out_tongue_winking_eye:

Yet another edit:
So on my Sony Xperia 1,the range became noticeable better, placing a coil on top.

… But the same procedure on a Samsung galaxy s10 didn’t improve at all.

The antenna designs are vastly different, so I assume th xperia has a more ‘concentrated’ beam, whilst the s10 has a broader coverage but a bit weaker overall signal :thinking::roll_eyes:

In any case, worth trying it out at least.



It looks like the coil has no chip or capacitor or anything, just two open leads… basically the coil is not connected to anything… is that the case?

That is correct. I removed the chip from the coil so it’s simply a coil over the existing phone antenna.

Edit: It seems the effect is purely psychological :unamused:
I tried reading a standard magic card, and managed to get a proper read from about 28mm both with and without the coil. - no difference

I then tried using the xfd, and had high hopes I could see a difference, as I got a good light all around the coil.
… But got the same result without the coil. (I think the NFC antenna is about the same size, only square)

I also tried to see if I could get any voltage difference on the proxmark, or increase in range on the xfd, but nothing.

The feel of increased range is simply because I now have a visual representation of where to place my implant, and so I place it correctly on the phone every time :neutral_face:


Good on you for further testing. It might improve things if you connected a proper capacitor tuned with that coil inductance to resonate at 13.56mhz

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