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PN7150 RF Timeout

Question asked by Mats Eliassen on Aug 30, 2019
Latest reply on Nov 1, 2019 by Mats Eliassen



I'm currently testing out the PN7150S NFC controller for a project.

For intial testing we're using the OM5578 dev. module with a Raspberry Pi running the linux_libnfc-nci stack (R2.4).


I'm currently integrating support for a rather proprietary NFC temperature sensor over ISO14443.

To read out the temperautre, the process is as follws:


#1 - Send 'start measurement process' command to the NFC chip

#2 - Wait > 400 ms.

#3 - Send 'read measurement result" command to the NFC chip and receive the temperature.


The communications is achieved using the nfcTag_transceive() function provided by linux_libnfc-nci.


My current issue is that during the > 400 ms wait period, the NFC chip disables it's RF interface.

This in turn causes the controller/stack to disable the RF field and restart the polling process (looking for tags).

When the field is lost, the NFC chip shuts down and the process needs to be restarted.


Searching the PN7150 user manual i found the 'TO_RF_OFF_CFG' parameter which "Specifies the time out (inms) applied by PN7150before it restarts a Polling sequence, after it has detected a Field OFF in Listen Mode".


Would increasing the value of this parameter from the default 300ms help with my issue?
If so, is there any way to change this setting trough linux_libnfc-nci configuration file or function?