Hello everybody,
we are working a contactless payment reader that will eventually be EMVCo Level 1 certified.
The Reader IC is a PN5190B1 with Firmware Version 2.7. The EEPROM settings are basically the standard EMVCo settings as delivered with NXP NFC Cockpit, with DPC calibration done for our antenna.
We are observing failures for the "TA135 - TA138" test cases ("Verifying the Load Modulation, at [...] Minimum/Maximum Negative Modulation"), which verify the receiver at the corner cases of negative load modulation.
Our reader is wrongly resetting the RF field after having received a SAK frame from the PICC (e.g. after step 10 of "C.1. Frame Trail for Type A PCD Tests"). Most likely because the SAK frame was corrupted.
In the picture below you see the SAK being send from the emulated PICC (this is a cilab 230 test system). And below that captured signal traces from the PN5190 receiver path (caputured via the Contactless Test Station module via NXP NFC Cockpit).
You can see in the sync_filt_out trace that there is a small disturbance at the end of the valid trace, which apparently causes the decoded data (rm_sdata) to append two bogus bits (01) to the received frame.
AN12549 (PN5190 antenna design guide) states:
However, due to a bad saturation and heating effect of the TESTPICC the “negative” load modulation can only be applied for a very short periodof time, which requires the test tool to switch the load before and after the response. This load switch causes EMD events, which need to be handled by the PCD, before these tests can be applied.
I assume that is what we are hitting here.
Could you please give me any hints about how to handle "[...] EMD events, which need to be handled by the PCD, before these tests can be applied."?
Thanks a lot for your help!
Michael
