The nRF52840 DK supports a Near Field Communication (NFC) tag.
NFC-A Listen Mode operation is supported on the nRF52840 System on Chip (SoC). The NFC antenna input is available on connector J5 on the nRF52840 DK.
NFC uses the NFC1 and NFC2 pins to connect the antenna. These pins are shared with the P0.09 and P0.10 General-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 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 L24 and J24 are by default configured to use the NFC antenna. To use these pins as GPIO, R44 and R46 must be not connected (NC) and R43 and R45 must be shorted with an OR resistor.