UG4 reading issues

Support
1

It seems like there are some issues with reading the flexUG4 with proxmark3. I’m able to read mine (already implanted in P3L).
I’m able to read it with Flipper zero. It took some time to figure out the correct placement, but now I’m able to read it basically always on first try.
The ACS ACR1252U can read it, but I have to press my hand into the exact middle.
My android phone (Pixel 7 pro) with NFC tools reads it basically like any other NFC tag.
However I was not able to read it with iPhone 13, although I haven’t spend much time trying.
Readers(sorry the only datasheet I found is in Czech) in our office building are also unable to read it.

I’m seeing more people in here having issues. So I think we should try to investigate more.

2

What about in this orientation and location?

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image404×469 54.6 KB

1 Like
3

the default configuration of the ug4 is a mifare classic 4k with a 4byte uid.

iphones cannot read mifare classic with nfctools.

you can use shortcut > automations to assign a trigger to the associated UID (this will stop working when you change the uid or length of the uid)

you can still read off records with background scanning providing they’re in the permitted records list.

for more compatibility, change the UG4 to be a NTAG chipset which will let you use it with nfctools on ios.

give this a read to understand nfc on iphones better and common limitations.

NDEF on iOS gist

1 Like
4

Yes, sorry I forget to specify. When I was trying to read it with both iphone and android it was configured as NTAG203 with url

5

This is the approximate location and orientation, but I have to really press my hand onto it.

6

To be specific this is the tag I was trying to read with iPhone, without any app active, just trying to read the Ndef url.

Screenshot_20250311-115924
Screenshot_20250311-1159241080×2400 184 KB

This was captured easily with my Pixel 7 pro