Can the rings hold 144 bytes or just 137?



  • I remember reading this project's Kickstarter page a year ago, thinking how wonderful it'd be to store my vCard on a ring. I looked around the Kickstarter page to find the rings capacity, and saw, in more than one place, the claim that each tag was capable of storing 144 bytes of information. I went to creating as small a contact card as I could, and managed to squeeze my name, number, and email in 143 bytes. Phew! I just made it, I thought. Indeed, even the current FAQ at http://store.nfcring.com/pages/faqs claims, "144 bytes, 1152 bits of awesomeness."

    But for some reason, the NXP NFC Writer app says the NTAG203, the NFC Ring's tag, only holds 137 bytes. As do several people on this forum who have been lucky enough to receive their rings:
    https://forum.nfcring.com/topic/291/my-perfect-nfc-ring-setup-nexus-5-android-4-4-3-rooted-encrypted
    https://forum.nfcring.com/topic/255/nfc-ring-and-sharing-contact-card/5
    https://forum.nfcring.com/topic/240/black-ring-feedback

    Are all these people mistaken? Does the NXP app use some bizarre metric for tags' storage capacities? Probably not... So what gives? Why tout 144, which, admittedly, is what this http://www.nxp.com/documents/short_data_sheet/NTAG203_SDS.pdf official-looking document says, when in practice, 137 is the number that matters? The ability to store my contact information was the reason I backed this project. I understand that Kickstarter projects guarantee nothing, and that end products need not live up to their advertised, original selves. My problem is that I've been following the NFC Ring religiously for the past year, reading every update and comment and watching every video. At no point did John or anyone else mention a storage capacity decrease (just look at the 144 in the current FAQ). So really, what gives?

    And before anyone suggests it: no, I can't make my name shorter, no, I can't make my work email shorter, and no, I can't make my phone number shorter. Yes, I can get rid of my email, but if that's what I have to resort to then there's no point using the ring to network. If all they'll be getting is my phone number, I might as well just call them.

    I hope I'm getting worked up over nothing, and that the rings really can store 1152 awesome bits. If you can verify this hope of mine or reject it, then please do, because I'd really like to know.



  • @turbomaze
    137 bytes, as you've seen, seems to be the amount of storage available. There was a thread about capacity where it was mentioned in passing that 144 is unformated, and 137 is usable space.

    The FAQ page should probably be updated to reflect this as every byte is important when you have so few.


  • Community Helper

    @shama is correct, @turbomaze. The space that is advertised by the IC manufacturer and everyone on down from that is 144 bytes, unformatted. It costs you 7 of those the first time you write an entry and the space is formatted, leaving you with 137 - it's the same with basically any data storage anywhere ever. We just notice it less now because we're not using floppy discs any more.



  • For anyone in the same boat as me, I'm planning on "solving" this problem by having my ring link to a website that displays all my contact info. It's not ideal, but it's better than nothing.


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