topic PN7462 Low Power Consumption Solutions in NFC

PN7462 Low Power Consumption Solutions

jackchan — Sat, 21 Jan 2017 15:00:55 GMT

Hi, Ladies and Gentalments,

I am using PN7462 CCID example with USB selective suspend and remote wakeup features.

When the device is entering suspend mode and insert a smart card, the card reader could be wakeup and work fine.

But it doesn't work if I am using nfc cards. The system will keep in the suspend state.

Becasue of the power consuption consideration, I am trying following solutions

1. RFLD: From the datasheet, PN7462 can detect RF level during sleep/standby mode. I am trying to change the wakeup config in the example code, but it doesn;t work for me. Does NXP have any document/examples to explain how to config RFLD to make system wakeup.

2. LPCD: From the documents, it says Low Power Card Detection function can save power by donfig the polling time. When I set the PHAC_DISCLOOP_CONFIG_ENABLE_LPCD feature to true in phExCcid_Clif.c and measuring the polling signal from anntena, the polling time is the same as the PHAC_DISCLOOP_CONFIG_ENABLE_LPCD was set to false. How dshould I do to enable LPCD feature on PN7462?

Any recommendation will be appreciated.

Thanks.

Jack#

Re: PN7462 Low Power Consumption Solutions

Jorge_Gonzalez — Mon, 20 Feb 2017 17:35:24 GMT

Hello Jack Chan,

My apologies for your unattended question.

1) RF Level Detector will not work to detect passive nfc cards, as there is no RF Field generated.

2) For the LPCD mode you need to make the next changes:

- In the file "phExCcid_Clif.c" change the LPCD enable parameter to "true" (I believe this is the step you already did):

wStatus = phacDiscLoop_SetConfig(psDiscLoopParams,PHAC_DISCLOOP_CONFIG_ENABLE_LPCD, true);‍

- Add the next macro to the file "APP_NxpBuild.h":

#define NXPBUILD__PHAC_DISCLOOP_LPCD       /**< SRC to enable LPCD is included. */‍

Regards!

Jorge Gonzalez

Re: PN7462 Low Power Consumption Solutions

jackchan — Tue, 21 Feb 2017 13:42:11 GMT

Hi, Jorge Gonzalez,

Thanks for your answer. but I have further questions:

1. for LPCD, I have done all you mentioned. But I measure the waveform of nfc TX, I can't see any difference between the LPCD on and off. Would you please provide a process to help me verify if my device works well?

2. The USB Selective Suspend of NFCCCID example. When I enable the usb selective suspend and remote wake up function by changing follow define:

#define PH_EXNFCCCID_USB_IF_USB_SUSPEND_RESUME_FTR 1 /**< Suspend Feature Value = 1 Feature Enabled Value = 0 Feature disabled */
#define PH_EXNFCCCID_USB_IF_USB_REMOTE_WAKEUP_FTR 1 /**< Remote Wake up Value = 1 Feature Enabled Value = 0 Feature disabled */

The LEDs will shift one by one when I attach my EVB to USB port and the LEDs will all out for awhile (entering the suspend mode) and shift again after 2 seconds (wakeup by the timer). The LED will stop on amber when I put an nfc card in the field (the card is detected) and starts the shift-out loop again. This is what I expected. The problem is the LEDs shifts-out loop can only least for sevral minutes (about 5~30 minutes in my tests). The LEDs will never on again then. The devices seems never wakeup again. Would you help on this?

Thanks.

Jack