Identifying keyfobs: EM4100 or T7755

Hello Flippees,

I hope my question isn’t stupid, I’m beginning with all those things :slight_smile:
I’d like to duplicate some keys.
From what I’ve understood, EM4100 doesn’t have enough memory for my keys (30-bit HID Proximity and Paradox).
My Flipper perfectly read and emulate them, so I bought key fobs, identified as T5577.

Writing my keys on them fail.
If I read them, it’s identified as EM4100. I edit the record and can write it on them. So the keyfob is writable.

Is there a way to be sure it’s not a T5577 ? (maybe writing a specific protocol on it ? )

btw: I’m having doubts about Flipper being able to write HID 30-bit protocols, I’ve seen in another thread that it supports only 26-bit (not sure if I well understood), that’s why I’m asking for another test (or maybe the name read by flipper is enough ? should it be identified as T5577 when read?).


EM4100 is not writeable. Do you mean EM4305?

With Flipper?
Flipper doesn’t support anything but T5577.

AFAIK it writes anything it can read and no more.

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T5577 Is not RFID protocol per se. T5577 emulates all other protocols. You can write any saved RFID fob into it.

I can successfully write EM4100 into T5577…

That’s what make blow my mind and having doubts :rofl:
Returning those keyfobs, will try an other vendor.

(or maybe the name read by flipper is enough ? should it be identified as T5577 when read?)

You will never see T5577 as RFID protocol, as it is only ‘emulator’.
IF you will Read for example FDX-B, and write it to T5577, it will read as FDX-B.

funny story: I read chip from my friend cat, write it to blank T5577 and mess with his head, by open his RFID ‘cat door’


Yes, I’ve understood that chips are the hardware layer, and we only see the protocol written on this hardware.
(but why we can see EM4100 ? is it a hardware+protocol linked ? made me doubt, that’s why I had this stupid question, just to be sure about T5577 and keyfobs I received :slight_smile: thanks all! )

Thanks for your answers.

From what I’ve seen, many vendors are selling keyfobs using EM4100, EM4305 or T5577 chips. So I ordered the best, a T5577.
You’re probably right about EM4100; I’m saying it’s an EM4100 just because Flipper is displaying it when I read the “default record”. (but I’m not sure the name is relevant as it can be changed?)

EM410x is a series of chips by EM Microelectronics, working on the same protocol. Flipper names it EM4100. Some Chinese clones use it, too, to be compatible and thus easy to add to existing systems.

There are no stupid questions :slight_smile: I’ll let Garrison finish the sentence. :slight_smile:


I received today my new keyfobs : it works perfectly !! I could write my keys on them.
So for newbies like me, be careful, many are selling fake T5577.
My last order is from “Yarongtech” his T5577 are real :slight_smile:
nb: when received, they were blank, nothing read by flipper (not like fake stuff ordered previously displaying em4100)


This question was really good. I purchased a black NFC device NS106 and was clueless what to do and how to do. I could read only EM41… and was not reading blank T5577. Then I tried to copy EM41… on T5577 FOB and to my surprise it wrote successfully. So I could use it after reading your question. Thanks…

Yup, that’s fine. T5577’s factory state, as documented in datasheet, doesn’t contain any meaningful info to send. Though some Chinese shops will ship their T5577 equivalents with some EM ID (unique or like 0000001234) written, for user’s convenience.