qi charger interferes with NFC causing dramatic increase power consumption

RE: qi charger interferes with NFC causing dramatic increase power consumption

Dajgoro Labinac — Thu, 08 Mar 2018 13:39:42 GMT

Seems the issue was caused by the version of the library I was using because the HAL_NFC_ENGINEERING_BC_FTPAN_WORKAROUND wasn't working for some reason. I wrote about the fix in this post:
devzone.nordicsemi.com/.../201644

RE: qi charger interferes with NFC causing dramatic increase power consumption

Dajgoro Labinac — Thu, 01 Mar 2018 13:18:19 GMT

When testing the SDK14 NFC example, after reading the nfc the power consumption jumps from normal to 25mA!
Edit: power consumption seems to be normal on another board, seems that the problem was board specific.

RE: qi charger interferes with NFC causing dramatic increase power consumption

Dajgoro Labinac — Thu, 01 Mar 2018 13:07:55 GMT

The issue regarding the NFC fix:

If you are using PCA10040 (part of nRF52 Development Kit), you must define the macro HAL_NFC_ENGINEERING_BC_FTPAN_WORKAROUND to apply workarounds for the following anomalies:

79. NFCT: A false EVENTS_FIELDDETECTED event occurs after the field is lost
NFCT does not release HFCLK when switching from ACTVATED to SENSE mode.

I can't get the fix to work, it seems to be supported on SDK11 as well, but it just does not work.
I also get the NFCT false event detection which proves that the fix does not work.

RE: qi charger interferes with NFC causing dramatic increase power consumption

Dajgoro Labinac — Wed, 28 Feb 2018 13:20:50 GMT

I think the issue might be because I'm using the SDK11, I did't switch to it yet because I was having issues with migrating the code before.

RE: qi charger interferes with NFC causing dramatic increase power consumption

Dajgoro Labinac — Wed, 28 Feb 2018 12:08:59 GMT

Not initializing the NFC removes the issue, but then I have no NFC.

RE: qi charger interferes with NFC causing dramatic increase power consumption

Dajgoro Labinac — Wed, 28 Feb 2018 11:19:12 GMT

I noticed also that just reading the NFC causes the issue, so after a bit of searching I found that there is a NFC anomaly in the HW that causes this problem. There seems to be a workaround, but I can't get it to work:
devzone.nordicsemi.com/.../qi-charger-interferes-with-nfc-causing-dramatic-increase-power-consumption

Seems like the bug should be fixed by the library itself, but its still occurring.

RE: qi charger interferes with NFC causing dramatic increase power consumption

Dajgoro Labinac — Tue, 27 Feb 2018 17:28:56 GMT

That wont help, even the qi periodic scanning pules are enough to trigger this issue, just swiping the qi charger near the antenna without having it engage is enough.
So by the time the charging is started its too late, the nRF is already glitched.

RE: qi charger interferes with NFC causing dramatic increase power consumption

hmolesworth — Tue, 27 Feb 2018 16:48:47 GMT

On a similar design I planned to reverse the NFC pins to active-low drive outputs for the duration of charging; maybe worth a try .. they may absorb some rf power, of course.