Simplicity SDK Platform Version 6.1.1 - Release Notes (Jul 29, 2026)#

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

Click here for earlier releases.

Release Summary#

Release Item	Version	Release Date	Release Notes	Key Features	API Changes	Bug Fixes	Chip Enablement
Platform MCU	6.1.1	Jul 29, 2026	Release Notes	Device Manager DMA and Device Manager I2C abstractions are now production quality. LLVM 21.1.1 compiler support for Series 2 and Series 3 platform applications.	None.	Fixes in UARTDRV and DMA Channel Driver. Updated reset-cause handling.	None.
Bootloader	3.3.1	Jul 29, 2026	Release Notes	None.	None.	Fixed a UsageFault that could occur during bootloader image verification and image information parsing. Fixed GCC Link Time Optimization (LTO) build issues affecting Series 2 and Series 3 bootloader core configurations. Fixed a GCC LTO build issue in the bootloader apploader configuration. Fixed bootloader component dependency metadata for TrustZone-aware configurations. Fixed an SMP-related issue in the bootloader code identified during Sonar and build validation.	None.
Security	6.1.1	Jul 29, 2026	Release Notes	None.	None.	Fixed a known issue (ID: 1556256) from Security Features 6.1.0. The TrustZone Secure Key Library (TZ SKL) could fail to build with the IAR toolchain due to an improper header file dependency that resulted in a circular include. Fixed an issue where code region configuration data could be erroneously removed during GCC or LLVM Link Time Optimization (LTO).	None.
Micrium OS	6.1.1	Jul 29, 2026	Release Notes	None.	None.	Corrected the Micrium OS Studio configuration option names `BSP_LF_CLK_SEL` and `CPU_CFG_CACHE_MGMT_EN`.	None.
CPC	4.9.1	Jul 29, 2026	Release Notes	Added LLVM compiler support for CPC applications.	Added `SL_CPC_ENDPOINT_MATTER` service endpoint ID for Matter NCP (Silicon Labs internal use only).	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	3.1.1	Jul 29, 2026	Release Notes	None.	None.	None.	None.

Impact of Release Changes#

Impact Statements | Migration Guide

Impact Statements#

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.
LLVM 21.1.1	LLVM 21.1.1 is now available as a supported compiler for Series 2 and Series 3 platform applications. 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, IAR 9.70.4, or LLVM 21.1.1.
- 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.

For information about Secure Vault Integration, see Secure Vault.

To review Security and Software Advisory notifications and manage your notification preferences:

Go to https://community.silabs.com/.
Log in with your account credentials.
Click your profile icon in the upper-right corner of the page.
Select Notifications from the dropdown menu.
In the Notifications section, go to the My Product Notifications tab to review historical Security and Software Advisory notifications
To manage your preferences, use the Manage Notifications tab to customize which product updates and advisories you receive.

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

Help and Feedback#

Contact Silicon Labs Support.
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SDK Release and Maintenance Policy#

See our SDK Release and Maintenance Policy.