The nRF52 PDK supports a Near Field Communication (NFC) tag.
NFC-A listen mode operation is supported on nRF52832. The NFC antenna input is available on connector P23 on the nRF52 PDK.
Figure 1. NFC antenna connector
NFC uses two pins, pin 11 (NFC1) and pin 12 (NFC2) to connect the antenna.
These pins are shared with GPIOs (P0.09 and P0.10) and the PROTECT field in the
NFCPINS register in UICR defines the usage of these pins and their protection level against
abnormal voltages. The content of the NFCPINS register is reloaded at every reset.
Important: The NFC pins are enabled by default. NFC can be disabled and GPIOs enabled
by defining the CONFIG_NFCT_PINS_AS_GPIOS variable in the project settings. This can be done
by defining the preprocessor symbol in Keil, go to: Project > Options for Target > C/C++
> Preprocessor Symbols > Define. Here you can add the CONFIG_NFCT_PINS_AS_GPIOS
variable after NRF52.
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 relocated to R27
and R28.This functionality can be removed by doing a nRFjprog --recover.
Figure 2. NFC input schematic
