Simplicity SDK Platform Version 6.1.0 - Release Notes (Jun 23, 2026)#

The Platform provides infrastructure support for applications developed with higher-level protocols, and it provides an interface with the underlying hardware.

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Release Summary#

Release Item	Version	Release Date	Release Notes	Key Features	API Changes	Bug Fixes	Chip Enablement
Platform MCU	6.1.0	Jun 23, 2026	Release Notes	ARM CMSIS upgraded from 5.8 to 6.2; GCC 14.2 Rel1 and IAR 9.70.4 supported. DMADRV is deprecated and replaced by `dma_manager`/`dma_channel` IAR support extended to SiXG301 (Series 3)	New: sl_main `app_init_post_platform()` hook.	Various fixes in Services and Drivers Addressed security and driver issues reported.	Added EFR32BG29 / EFR32MG29 (Rev2) OPN and radio board support. Added EFR32FG2D and WPK Main Board (BRD4002B) support.
Bootloader	3.3.0	Jun 23, 2026	Release Notes	Added support for the BRD4419A evaluation board. Updated the default Series 3 bootloader clock configuration to use SoCPLL at 145 MHz sourced from HFRCO. Added support for dynamic application image selection in dual-application bootloaders using a flash-based switch mechanism.	Updated bootloader return types from `int32_t` to `btl_ret_t` for IAR build compatibility.	Fixed a bootloader hard fault caused by invalid bootload information read from external flash. Fixed a crash caused by invalid application properties pointers during application version checks. Fixed internal storage slot overlap with NVM on 768 kB devices. Fixed IAR build failures for Series 2 bootloader applications when glitch mitigation is disabled.	Added support for the xG2B device family.
Security	6.1.0	Jun 23, 2026	Release Notes	Added support for NIST SP 800-108r1 key derivation, enabling PUF-based key derivation on xG27 devices.	Added new fine-grained SLC components for Mbed TLS X509, PK, SSL, and DTLS client/server APIs to reduce code size for specific use cases.	Fixed an issue where application properties could be optimized out during LTO (GCC) in the TrustZone Secure Key Library Attestation Service. Fixed an issue where the return code could be overwritten in the TrustZone Secure Key Library Attestation Service.	None.
Micrium OS	6.1.0	Jun 23, 2026	Release Notes	None.	None.	Fixed `OSTimeDly()` overflow that caused TimeTask to run continuously after ~36.4 hours.	None.
CPC	4.9.0	Jun 23, 2026	Release Notes	None.	None.	Fixed a threading issue where a CPC endpoint opened in one thread could report an inconsistent state after being closed from another thread. Fixed compile errors that prevented Secondary SPI projects from building after switching from the UART recommended interface to the SPI recommended interface.	None.
RAIL Library	3.1.0	Jun 23, 2026	Release Notes	None.	None.	None.	None.

Impact of Release Changes#

Impact Statements | Migration Guide

Impact Statements#

Item Impact

ARM CMSIS 6.2 upgrade

Item	Impact
ARM CMSIS 6.2 upgrade	The `osThreadAttr_t` structure replaces the `reserved` member with `affinity_mask`. Applications that initialize `.reserved` in `osThreadAttr_t` initializer lists must remove it. This release includes a union-based compatibility layer to ease migration when the deprecated `.reserved` member is still referenced. Do not initialize `.reserved` or `.affinity_mask` to 0; omit these members and rely on implicit zero-initialization for const structs with static storage.
GCC 14.2 Rel1	GCC updated from 12.2.1 to 14.2 Rel1. On Windows and macOS (Apple Silicon), use the Silicon Labs-provided GCC 14.2 Rel1 toolchain to build with LTO-enabled SDK libraries. Using the ARM-released GCC toolchain on these platforms with LTO enabled may result in link-time errors.
IAR 9.70.4	IAR updated from 9.40.1 to 9.70.4. Rebuild all projects after upgrading the toolchain.

The osThreadAttr_t structure replaces the reserved member with affinity_mask. Applications that initialize .reserved in osThreadAttr_t initializer lists must remove it. This release includes a union-based compatibility layer to ease migration when the deprecated .reserved member is still referenced.

Do not initialize .reserved or .affinity_mask to 0; omit these members and rely on implicit zero-initialization for const structs with static storage.

GCC 14.2 Rel1

GCC updated from 12.2.1 to 14.2 Rel1. On Windows and macOS (Apple Silicon), use the Silicon Labs-provided GCC 14.2 Rel1 toolchain to build with LTO-enabled SDK libraries. Using the ARM-released GCC toolchain on these platforms with LTO enabled may result in link-time errors.

IAR 9.70.4

IAR updated from 9.40.1 to 9.70.4. Rebuild all projects after upgrading the toolchain.

Migration Guide#

ARM CMSIS 6.2 migration:

Remove the .reserved member from all osThreadAttr_t initializer lists. Only initialize members that require non-zero or non-NULL values.

Example:

static const osThreadAttr_t thread_attributes = {
  .name       = "app",
  .stack_size = 3072,
  .priority   = osPriorityLow,
};static const osThreadAttr_t thread_attributes = {
  .name       = "app",
  .stack_size = 3072,
  .priority   = osPriorityLow,
};

Compiler upgrade:
- Rebuild all projects after upgrading to GCC 14.2 Rel1 or IAR 9.70.4.
- On Windows and macOS (Apple Silicon), install the Silicon Labs-provided GCC 14.2 Rel1 toolchain through Simplicity Installer / SLT when building with LTO.
DMADRV: The DMADRV component and all DMADRV APIs are now deprecated. They remain functional in this release and are scheduled for removal in the future. For new designs, use the dma_manager service and the dma_channel driver. Software components that previously used the DMADRV API, including SPIDRV and UARTDRV, have been migrated to the dma_manager service and dma_channel driver in this release. For more information, see the DMADRV Migration Guide.

Using This Release#

Installation and Use | Help and Feedback

Installation and Use#

To run your first demo, see our Getting Started Guides.

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To learn more about the software in this release, dive into our online documentation.

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SDK Release and Maintenance Policy#

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