Custom nrf52840 board (NOT the nRF52840DK), problems using pin 10 as GPIO (i.e. problems disabling NFC)

RE: Custom nrf52840 board (NOT the nRF52840DK), problems using pin 10 as GPIO (i.e. problems disabling NFC)

jeremysf — Tue, 31 Jul 2018 06:21:34 GMT

Ok, so the footprint is fine, it looks like the example I copied it from had some bad net names. Ugh!

Still not sure how things were "partially" working, I must have set P1.09 somehow when debugging, but regardless, things are working great now.

RE: Custom nrf52840 board (NOT the nRF52840DK), problems using pin 10 as GPIO (i.e. problems disabling NFC)

jeremysf — Mon, 30 Jul 2018 16:22:41 GMT

Oh, the comment about P1.10 got me thinking, and I checked the datasheet against my schematic and layout.

i am using Autodesk EAGLE and the nRF52840 footprint from Nordic’s GitHub repository.

Looking at my design in EAGLE, it appears several of the pins in that footprint are incorrect. What I routed to is actually P1.09 and not (as labeled in the Nordic provided EAGLE footprint) P0.10:

eyrie.io/.../a8ad48a1be26430ca63f2aad44afaaaa

I will check the actual PCB later today, but I’m hopeful because if so I can avoid re-spinning new boards.

I’m still trying to figure out how I saw any signal at all out of P1.09 (when I was trying to set P0.10).

RE: Custom nrf52840 board (NOT the nRF52840DK), problems using pin 10 as GPIO (i.e. problems disabling NFC)

Håkon Alseth — Mon, 30 Jul 2018 07:11:31 GMT

Hi,

[quote user=""]My application is based on the ble_hrs app and stripped down pretty bare. I can't find anything in config.h that seems related to NFC or pin 0.10. Is there some kind of built-in toggling of the NFC that happens in the softdevice to keep it from conflicting with BLE?[/quote]

No, there is no relation between the softdevice and NFC.

[quote user=""]Is there something else I should be adding to my config.h, makefile, etc to force off NFC using pin 0.10? Any other ideas of things that could be modifying pin 0.10?[/quote]

On a custom design, the only thing you need to do is to define CONFIG_NFCT_PINS_AS_GPIOS, then use the pins P0.09 and P0.10 as you would normally. Since you're using nrf52840; you did not route P1.10 instead of P0.10?

There is one more step you'll need to do if using the nRF52-DK or nRF52840-DK, which is to move two 0-ohm resistors:

http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52/dita/nrf52/development/nrf52840_pdk/hw_nfc_if.html?cp=2_0_3_7_12

Kind regards,

Håkon

RE: Custom nrf52840 board (NOT the nRF52840DK), problems using pin 10 as GPIO (i.e. problems disabling NFC)

jeremysf — Mon, 30 Jul 2018 05:42:17 GMT

Well, now I can’t get any output on pin 10 at all. I can confirm that the UICR for the NFC is clear (ie. 0xfffffffe) but I see no output via scope or logic analyzer.

I built the blinky sample with -DCONFIG_NFCT_PINS_AS_GPIOS and I can set adjacent pins but not pin 10 (my board does not have a trace for pin 9).

I have no easy way to verify the solder joint on pin 10, but I did hot air and reseat the device, but still no output.

I just ordered an nRF52840 eval board, which I will modify the NFC antenna resistors on, and see if I can get things working there.

twitter.com/.../1023641614164488193