NFC: Writable NDEF message
The Writable NDEF message sample shows how to use the NFC tag to expose an NDEF message that can be overwritten with any other NDEF message by an NFC device. It uses the NFC Data Exchange Format (NDEF).
The sample supports the following development kits:
When built for an
_ns build target, the sample is configured to compile and run as a non-secure application with Cortex-M Security Extensions enabled.
Therefore, it automatically includes Trusted Firmware-M that prepares the required peripherals and secure services to be available for the application.
The sample also requires a smartphone or tablet with NFC Tools application (or equivalent).
When the sample starts, it initializes the NFC tag and loads the NDEF message from the file in flash memory. If the NDEF message file does not exist, a default message is generated. It is a URI message with a URI record containing the URL “nordicsemi.com”. The sample then sets up the NFC library for the Type 4 Tag platform, which uses the NDEF message and senses the external NFC field.
The library works in Read-Write emulation mode. In this mode, procedures for reading and updating an NDEF message are handled internally by the NFC library. Any changes to the NDEF message update the NDEF message file stored in flash memory.
- LED 1:
Indicates if an NFC field is present.
- LED 2:
Indicates that the NDEF message was updated.
- LED 4:
Indicates that the NDEF message was read.
- Button 1:
Press during startup to restore the default NDEF message.
This sample can be found under
samples/nfc/writable_ndef_msg in the nRF Connect SDK folder structure.
When built as firmware image for the
_ns build target, the sample has Cortex-M Security Extensions (CMSE) enabled and separates the firmware between Non-Secure Processing Environment (NSPE) and Secure Processing Environment (SPE).
Because of this, it automatically includes the Trusted Firmware-M (TF-M).
To read more about CMSE, see Processing environments.
To build the sample with Visual Studio Code, follow the steps listed on the How to build an application page in the nRF Connect for VS Code extension documentation. See Building and programming an application for other building and programming scenarios and Testing and debugging an application for general information about testing and debugging in the nRF Connect SDK.
If you are using debug messages in the NFCT driver, the driver might not be working properly if you have
The NFCT driver is part of the nrfx driver package.
For more information about this driver, see the NFCT driver page in the nrfx repository.
After programming the sample to your development kit, complete the following steps to test it:
Touch the NFC antenna with the smartphone or tablet and observe that LED 1 and LED 4 are lit.
Observe that the smartphone or tablet tries to open the URL “http://www.nordicsemi.com” in a web browser.
Use a proper application (for example, NFC Tools for Android) to overwrite the existing NDEF message with your own message.
Restart your development kit and touch the antenna again. Observe that the new message is displayed.
This sample uses the following nRF Connect SDK libraries:
In addition, it uses the Type 4 Tag library from sdk-nrfxlib:
It uses the following Zephyr libraries:
The sample also uses the following secure firmware component: