nRF Connect SDK v2.5.3 Release Notes

nRF Connect SDK delivers reference software and supporting libraries for developing low-power wireless applications with Nordic Semiconductor products in the nRF52, nRF53, nRF70, and nRF91 Series. The SDK includes open source projects (TF-M, MCUboot, OpenThread, Matter, and the Zephyr RTOS), which are continuously integrated and redistributed with the SDK.

Release notes might refer to “experimental” support for features, which indicates that the feature is incomplete in functionality or verification, and can be expected to change in future releases. To learn more, see Software maturity levels.

Highlights

This patch release adds changes on top of the nRF Connect SDK v2.5.0, nRF Connect SDK v2.5.1, and nRF Connect SDK v2.5.2. The changes affect Matter, Wi-Fi®, Bluetooth®, and Zephyr.

See Changelog for the complete list of changes.

Release tag

The release tag for the nRF Connect SDK manifest repository (https://github.com/nrfconnect/sdk-nrf) is v2.5.3. Check the west.yml file for the corresponding tags in the project repositories.

To use this release, check out the tag in the manifest repository and run west update. See Get the nRF Connect SDK code and Examples of commands for more information.

For information on the included repositories and revisions, see Repositories and revisions for v2.5.3.

IDE and tool support

nRF Connect for Visual Studio Code extension is the recommended IDE for nRF Connect SDK v2.5.3. See the Installation section for more information about supported operating systems and toolchain.

Supported modem firmware

See Modem firmware compatibility matrix for an overview of which modem firmware versions have been tested with this version of the nRF Connect SDK.

Use the latest version of the nRF Programmer app of nRF Connect for Desktop to update the modem firmware. See Updating the modem firmware for instructions.

Modem-related libraries and versions

Modem-related libraries and versions

Library name	Version information
Modem library	Changelog
LwM2M carrier library	Changelog

Known issues

Known issues are only tracked for the latest official release. See known issues for nRF Connect SDK v2.5.3 for the list of issues valid for the latest release.

Changelog

The following sections provide detailed lists of changes by component.

Protocols

This section provides detailed lists of changes by protocol.

Bluetooth

Fixed an issue where the Bluetooth host running on the nRF5340 application core might deadlock on disconnection (DRGN-21390).

Wi-Fi

• Added:

• Build-time disconnection timeout configuration.

• The following fixes and improvements:

  • Wi-Fi stuck in an awake state.

  • Frequent Wi-Fi disconnections in a congested environment and low RSSI.

  • HTTPS upload and download performance issues.

  • MQTT disconnection in a congested environment and low RSSI.

  • Selecting the best RSSI access point.

  • Rate adaptation enhancements to improve range in 2.4 GHz band.

To accommodate all fixes and improvements, there is a one kB increase in the stack usage of the WPA supplicant and the user must increase the stack sizes appropriately in their applications.

• Updated the WPA supplicant to reserve libc heap memory rather than using leftover RAM. This does not affect the overall memory used, but now the RAM footprint as reported by the build will show higher usage.

Matter

• Updated:

  • The default Message Reliability Protocol (MRP) retry intervals for Thread devices to two seconds to reduce the number of spurious retransmissions in Thread networks.

  • Increased the number of available packet buffers in the Matter stack to avoid packet allocation issues.

Samples

This section provides detailed lists of changes by sample.

Matter samples

• Matter: Door lock sample:

  • Added support for emulation of the nRF7001 Wi-Fi companion IC on the nRF7002 DK.

Zephyr

The Zephyr fork in nRF Connect SDK (sdk-zephyr) contains all commits from the upstream Zephyr repository up to and including a768a05e6205e415564226543cee67559d15b736. It also contains some nRF Connect SDK specific additions and commits cherry-picked from the upstream Zephyr repository including the following one:

• Fixed the GPIO configuration that is used in the pinctrl driver for the QSPI IO3 line. Due to these incorrect settings, the QSPI NOR flash driver could not initialize successfully for a flash chip configured to work in non-Quad (2 I/O) mode.

For a complete list of nRF Connect SDK specific commits and cherry-picked commits since v2.5.0, run the following command:

git log --oneline manifest-rev ^v3.4.99-ncs1