NFC passive tag

Nordic Thingy:91™ supports an Near Field Communication (NFC) passive tag. Nordic Thingy:91 can use this tag function for the Out of Band pairing feature as described in the Bluetooth Core Specification. NFC-A listen mode operation is supported on the nRF52840.

The NFC passive tag antenna input is available on connector J5.

Figure 1. NFC passive tag antenna connector

The NFC passive tag uses two pins, F1 (NFC1) and E2 (NFC2), to connect the antenna. These pins are shared with General-Purpose Input/Output (GPIO)s (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.

Note: The NFC passive tag pins are enabled by default.

The NFC passive tag can be disabled and the GPIOs enabled by defining the CONFIG_NFCT_PINS_AS_GPIOS variable in the project settings. The way of doing this depends on the Integrated Development Environment (IDE) or toolchain in use.

When using SEGGER Embedded Studio, go to Project > Edit Options > Code > Preprocessor > Preprocessor Definitions and add the CONFIG_NFCT_PINS_AS_GPIOS variable.
When using Keil, go to Project > Options for Target > C/C++ > Preprocessor Symbols > Define and add the CONFIG_NFCT_PINS_AS_GPIOS variable.