nRF52 Preview DK v1.1.x

NFC antenna interface

The nRF52 Preview Development Kit board 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 Preview Development Kit board.

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.

This functionality can be removed by doing a nRFjprog --recover.

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.
Figure 2. NFC input schematic
NFC input schematic on the nRF52 Preview Development Kit


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