NFC PN5180 DPC in Card Emulation Mode

[emmanuel_sanche]

I'm having an issue where the RF field gets really weak on my NFC antenna after I use a phone to read it once or twice.

I am using the PN5180 in card emulation mode. Does the PN5180 use the DPC in card emulation mode??

I am unable to calibrate the DPC because my measurement of the current ITVDD it is always 0mA,

and I think it's because I'm using the PN5180 in card emulation mode.

I'm not sure if my problem is with the DPC or with the hardware on my custom board.

For testing purposes, I tried reducing the gears in the DPC to 1, as described below, but it did not fix my issue.

This is related to the problem described here:

https://community.nxp.com/thread/502914 

Any ideas?

Thank you

[Kan_Li]

Hi,

I tried the example of NfcrdlibEx8_HCE_T4T on PNEV5180B, and my phone can detect the type 4 tag at the range of about 2cm, and distance is always 2cm or so after multiple tests. Would you please try this example as well? so we could confirm if it is a hardware issue or software issue.

BTW, I used TagInfo App running on an Android phone in this test.

Have a great day,
Kan

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[emmanuel_sanche]

Hi,

I know that the example NfcrdlibEx8_HCE_T4T works because I also tested it on the PNEV5180B and I have no issues. 

My problem is that I have a custom PCB that has an issue with the antenna sensitivity (NFC PN5180 Antenna Sensitivity Problem ) and I don't know if it's a problem with the hardware or with bad EEPROM settings related to the Dynamic Power Control (DPC) or Adaptive Receiver Control (ARC) or Automatic Gain Control (AGC)???

The phone will read it OK once or twice at a distance of about 2.5cm, but then the sensitivity drops and I can only read it at about 1mm.

I am trying to determine if my DPC calibration is the problem, but my ITVDD measurement is always 0mA. This tells me that the DPC is not used in card emulation mode. Is this correct??

Ideas?

Thank you!

[Kan_Li]

Hi,

Is it possible to run the example NfcrdlibEx8_HCE_T4T on your custom PCB? so we could know where is the problem from the test result.

Have a great day,
Kan

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[emmanuel_sanche]

Hi,

Please read my last 2 replies posted on Aug 22. I tested both NfcrdlibEx8_HCE_T4T and NfcrdlibEx3_NFCForum on my custom PCB. 

NfcrdlibEx3_NFCForum works fine always.

NfcrdlibEx8_HCE_T4T works but the reading range gets very low after a couple phone reads.

I think this is a question for the PN5180 engineers and not a problem with the NFC library.

I'm not sure if my card emulation performance could be affected by a bad EEPROM setting, or if there's a specific component in the matching circuit that only affects card emulation mode.

Is there a PN5180 engineer who can help answer this question?

Thank you!

[Kan_Li · Accepted solution]

Hi,

Since NfcrdlibEx8_HCE_T4T works well on PNEV5180B, I think this should be a hardware issue, please check if the antenna tuning for card mode was done on your custom board, this kind of tuning is different from reader mode, you may refer to "4.3.1 Antenna tuning for RM and CM" in https://www.nxp.com/docs/en/application-note/AN11740.pdf  for more details.

NfcrdlibEx3_NFCForum demonstrate both Peer to Peer (P2P) and Reader functions but not the card mode.

DPC doesn't work for card mode, as the device doesn't generate RF field during the card mode.

Hope that makes sense,

Have a great day,
Kan

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[emmanuel_sanche]

In section "4.3.1", the antenna is tuned to both RM and CM. Is it possible to only tune it to CM without also tuning for RM? I noticed that when I tune for CM, my RM simulation looks bad. However, I only care about CM for my application.

Thank you

[Kan_Li]

Though we normally tune the antenna for both RM and CM, of course you may just tune it for CM.

Have a great day,
Kan

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[emmanuel_sanche]

I think my issue are the resistors on pins RXP and RXN. Lowering them from 4.7k to 3.2k improved the performance for card mode. Maybe finding the optimal value for these resistors (section 4.5.1 External Rx Components) will fix the sensitivity problem completely.

[emmanuel_sanche]

What you said makes perfect sense! I think the board was only tuned for reader mode and not for card mode.

Thank you for your help!

Emmanuel

[emmanuel_sanche]

I tried a different example (NfcrdlibEx3_NFCForum) on my custom board, and I'm able to use the phone to read the "www_nxp_com" message successfully and consistently at a distance of about 2cm without sensitivity problems. I only have the sensitivity problem in card emulation mode. What EEPROM settings or hardware components could be affecting the card emulation mode???

Thank you!