NFC unique adress?

[Inspectron]

Does NFC has something like an unique adress?

Because the nfc examples in the sdk detect all nfc devices. But I would like to detect only predefined devices.

Or is there another way to detect only specific defined devices trough nfc?

[Eirik Midttun]

NFC tags has a unique address and are required to have it. However, I won't solve your issue.

I assume you are talking about nRF52 examples, in which case your statement on detection is somewhat mistaken. nRF52 will be an NFC tag and will therefore be detected by devices, not the other way round. In particular, and related to spec compliance, the device will request the ID of the tag. So the device can identify the tag, but the tag has no way of identifying a device.

By design an NFC tag is passive device that doesn't decide anything on its own. And for the ID the main purpose is collision resolution; imagine putting your wallet next to an NFC device and you have more than one NFC card.

[Inspectron]

Yes, this makes sense to me. Thank you for the support! What a pity, it would be a nice doorlock solution...

[Alex]

You can still use it as doorlock if you use password protection. So your tag will accept write from device only if password matches. But I'm not sure if that function implemented in nRF52, should be.

[Eirik Midttun]

Currently the WRITE operation is not supported by the NFC library in the SDK. It is possible to implement a Tag 2 library with WRITE if required.

Most door locks using NFC are devices/pollers, meaning they generate a field. This cannot be done with nRF52. How do you imagine the door lock being an NFC tag?

[Inspectron]

@ Alex : I know, but passwort protection takes to long. A door lock where you just need your mobile device without any applications or passwords, this would be interesting.

@ Eirik : Well, there is an nfc_callback function, which will be called when the tag is detected. But you will always jump in this function when the tag will be detected. And I would like to detect only predefined devices. But as I understand, only over nfc it wont be able to detect which device(unique adress) is detected.

[Alex]

Eirik, I don't know what is implemented in nRF52 but using nRF51 with passive Tag M24SR64 for example can be a doorlock. It is passive and if password over RF enabled then only device which knows password can write to the tag. ARM can recognize successful writing and perform operation accordingly. It is just idea, I have no idea how other doorlocks done. But if Inspectron wants that configuration then it is the solution. And mobile phone obviously needs application running to unlock the door