NFC - passive card removal detection

[me3]

in regard to the PN7120:
is there a way to passively detect when a NFC device/card is physically removed from the chip?
android, in recent versions, supports this, and i would like replicate this behaviour with my NXP NFC hardware.

[Kan_Li]

Yes, such kind of event can be detected. Please refer to the following for more details.

Have a great day,
Kan

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[me3]

thank your for your reply, but i am not sure what you are suggesting?
i am specifically looking for a way to passively detect card removal.
WITHOUT sending commands to the nfc card, as i must not disrupt the communication flow.
this is in regard to nfc chipcards not simple tags.

[Kan_Li]

What do you mean "WITHOUT sending commands to the nfc card"? Would you please specify the use case? Generally when the card is close to the device, the communication would start automatically. Do you want the PN7120 report this kind of event when the card is suddenly removed during the communication? Please kindly clarify.

Have a great day,
Kan

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[me3]

we built a NFC card reader based on PN7120. we connect it to a smartphone or PC and use it to read e.g. credit cards or government IDs. the command APDUs come from the connected device, the reader just passes them through. the reader is not allowed to send its own APDUs to the card, as this would potentially interrupt the communication between the card and the device.

now we want to detect when a connected card is removed from the reader. we need to do so without sending any APDUs (detect passively, not actively).

android has a feature to achieve exactly that, with the built in NFC hardware already.

we want to know if this is possible with the PN7120 in our reader as well and if so, how?

thanks for your help!

[Kan_Li · Accepted solution]

Hi Alex,

Thanks for the clarification! Referring to UM10819, it can not detect the card removal without MCU side's activity, please refer to the following for more details.

Have a great day,
Kan

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