NFC uses the NFC1 and NFC2 pins to connect the antenna.
These pins are shared with the P0.09 and P0.10General-Purpose Input/Output (GPIO)s. The PROTECT field of the NFCPINS register in
User Information Configuration Registers (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.
Configuring NFC pins as GPIOs
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 is configured based on
the Integrated Development Environment (IDE) or toolchain in use:
SEGGER Embedded Studio – Select Project > Edit Options > Code > Preprocessor > Preprocessor Definitions and add the CONFIG_NFCT_PINS_AS_GPIOS variable.
nRF Connect SDK – Set CONFIG_NFCT_PINS_AS_GPIOS to y. For instructions,
see Configuring and building.
Pins P0.09 and P0.10 are by default configured to use the NFC antenna. To use
these pins as GPIO, R25 and R26 must be not connected (NC) and R27 and R28 must be shorted with an OR resistor.