PN7150

[Electronics_Engineer]

Hello everyone,

I have used the PN7150 NFC chip in autonomous polling mode with LPCD disabled.

I can detect NFC Tag and can see NFC coil signals are changing as the NFC tag is detected.

PN7150 VDDTx current consumption is  25mA when NFC Polling is occurring and 230mA when NFC Tag is detected.

But when the NFC tag is removed, current consumption is still 230mA and signals are observed on the NFC coil same when a tag was detected. The image is attached herewith.

Is there is any way that PN7150 will stop RF activity as soon as Tag is removed without initiating 

[Fabian_R]

Hello sir,
Thank you for using our products, we really appreciate it.
Could you please let me know which MCU are you using and if you are using the NCI example we provide on the PN7150 summary page?
If you please open any example, NxpNci_StopDiscovery() is called after the "CARD REMOVED" printf in the nfc_task.c file.
Please let me know if this function is implemented in your application.

[Electronics_Engineer]

@Fabian_R 

Thank you for the response. I am using MWCT1013 MCU and I have used same NCI example code as mentioned. Yes, there is NxpNci_StopDiscovery() is called after the "CARD REMOVED" printf in the nfc_task.c file.

My question is why there is still RF signals visible even we remove a tag from the surface?

Can PN7150 notify DH if the NFC tag is removed?

Can PN7150 switch to RFST_DISCOVERY state after the NFC tag is removed??

Thanks in advance

[Electronics_Engineer]

@Fabian_R 

One more query, I want more explanation on this.

As per NCI Specifiaction V2.0 document :

After an RF Interface has been activated, the DH can communicate with the Remote NFC
Endpoint using the activated RF Interface. An activated RF Interface can be deactivated by either
the DH or the NFCC (e.g., on behalf of the Remote NFC Endpoint). However each RF Interface
can define which of those methods are allowed. There are different deactivation options
depending on which part of the protocol stack is executed on the DH. For example if a protocol
command to tear down the communication is handled on the DH, the DH will deactivate the RF
Interface. If such a command is handled on the NFCC, the NFCC will deactivate the Interface.

I want NFCC(PN7150) to deactivate RF if Tag is removed from the surface.

Is it possible ??

Thanks in advance

[Fabian_R]

Yes, the PN7150 can notify the DH that the tag is removed. This is at the NfcLibrary, under the NXPNci directory. You can call the NxpNci_CheckDevPres() function, this function should return an NXPNCI_SUCCESS in case a device has been detected.

Regarding the possibility of switching to RFST_DISCOVERY after a tag is removed, this state is triggered for discovering new tags, not after removing one. The DH needs to send the discover command again in order for this to happen. (check section 9 of the UM10936)

About the possibility of deactivating the RF, this will have to be implemented by yourself using the RF_DEACTIVATE_CMD which as mentioned in the User Manual, is fully supported by the PN7150. (Check Section 4.2.2)