Porting from NRF51 to NRF52 P0.9,PO.10 GPIO Problem

[Doug_H]

My board requires P0.9 and P0.10 to operate as GPIO pins. On the NRF52 these pins share the function with the NFC antenna. How do I make them function as GPIO pins?

I know this question has already been asked, but I have tried the posted solutions and they have not worked, so I am posting a new help request.

I am testing this on PCA10040. Here's what I have tried so far:

I added UICR configuration to set UICR register 0x1000120C to 0xFFFFFFFE and verified with "nrfjprog --memrd 0x1000120C --n 4" that the value of 0xFFFFFFFE was correctly set. (NOTE: On my PCA10040 board the UICR 0x20C was already set to 0xFFFFFFFE which is not consistent with the datasheet, in any case, I explicitly set it to 0xFFFFFFFE to be sure).

I added the project level define: CONFIG_NFCT_PINS_AS_GPIOS to the Preprocessor symbols in the configure options for target tabbed dialog box.

All my other GPIO pins function correctly but P0.9 and P0.10 will not work. What am I doing wrong?

[RK]

What you're doing wrong is not reading the manual. I didn't read it either and spent at least an hour messing around with P0.9 and P0.10 before I did

Pin 11 and pin 12 are by default configured to use the NFC antenna, but
if pin 11 and pin 12 are needed as  normal GPIOs, R25 and R26 must be NC
and R27 and R28 must be shorted by 0R.

The pins aren't actually connected to the GPIOs on the dev board.

[Øyvind Karlsen]

Hi,

The GPIO pins are used for NFC, as you have figured out. To be able to use those pins on the dev board you have to do some hardware modifications. Please see the infocenter on the NFC interface for more information.

Best regards,

Øyvind

[Doug_H]

That was it! Thanks for the help, everything is working correctly now.