Simplicity SDK Platform - Bootloader Version 3.3.1 - Release Notes (Jul 29, 2026)#

Simplicity SDK Platform Version 6.1.1

The Gecko Bootloader is a common bootloader framework used across modern Silicon Labs MCUs and wireless SoCs. It offers configurable features such as device initialization and secure firmware updates.

Release Summary#

Key Features | API Changes | Bug Fixes | Chip Enablement

Key Features#

Added in 3.3.1#

  • None

Added in 3.3.0#

  • 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.

API Changes#

Changed in 3.3.1#

  • None

Changed in 3.3.0#

  • Updated bootloader return types from int32_t to btl_ret_t for IAR build compatibility.

Bug Fixes#

Fixed in 3.3.1#

  • 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.

Fixed in 3.3.0#

  • 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.

Chip Enablement#

Added in 3.3.1#

  • None

Added in 3.3.0#

None.

Key Features#

New Features | Enhancements | Removed Features | Deprecated Features

New Features#

Added in 3.3.1#

  • None

Added in 3.3.0#

  • Added a new Switch Multi-Protocol (SMP) feature that enables dual-application bootloaders to dynamically select and boot either App 1 or App 2 using a two-page flash-based switch mechanism.

Enhancements#

Added in 3.3.1#

  • None

Added in 3.3.0#

  • Added GCC Link Time Optimization (LTO) build support for Series 2 and Series 3 bootloader applications.

  • Updated the default Series 3 (SiWx301) bootloader clock configuration to use SoCPLL at 145 MHz sourced from HFRCO for improved out-of-box bootloader performance.

Removed Features#

None.

Deprecated Features#

None.

API Changes#

New APIs | Modified APIs | Removed APIs | Deprecated APIs

New APIs#

None.

Modified APIs#

Modified in 3.3.1#

  • None

Modified in 3.3.0#

Modified API Signature

Previous API Signature

btl_ret_t bootload_verifyApplication(uint32_t startAddress)

int32_t bootload_verifyApplication(uint32_t startAddress)

btl_ret_t bootload_storeApplicationVersion(uint32_t startAddress)

int32_t bootload_storeApplicationVersion(uint32_t startAddress)

btl_ret_t bootload_verifySecureBoot(uint32_t startAddress)

int32_t bootload_verifySecureBoot(uint32_t startAddress)

Removed APIs#

None.

Deprecated APIs#

None.

Bug Fixes#

Fixed in 3.3.1#

ID Issue Description GitHub / Salesforce Reference (if any) Affected Software Variants, Hardware, Modes, Host Interfaces
1680408 Fixed an issue that could trigger a UsageFault while the bootloader verified an image or parsed image metadata, improving reliability during image validation and startup. None None
1649284 Fixed build issues when compiling Series 2 and Series 3 bootloader core configurations with GCC LTO enabled. None None
1666290 Fixed a GCC LTO compatibility issue that prevented bootloader apploader configurations from building successfully. None None
1672058 Updated bootloader component dependency metadata to correctly support TrustZone-aware configurations during project setup. None None
1657262 Fixed an issue in the SMP-related bootloader code to improve reliability and maintainability. None None

Fixed in 3.3.0#

ID Issue Description GitHub / Salesforce Reference (if any) Affected Software Variants, Hardware, Modes, Host Interfaces
1569692 Resolved an issue where invalid BootloadInfo length values read from external SPI flash could cause the CRC validation routine to access memory outside valid bounds, resulting in a hard fault during firmware update operations. The bootloader now validates bootload information header fields before performing CRC checks to prevent invalid memory access. None

None
1543959 Updated bootload_checkApplicationPropertiesMagic() for Series 2 bootloaders to validate that the application properties pointer lies within the configured application space and flash bounds. Out-of-range pointers are now rejected to prevent crashes during application version checks. None

None
1569149 Reduced the internal storage slot size in the bootloader-storage-internal-single-768k sample from 368 kB to 352 kB to prevent overlap with NVM regions on 768 kB devices. None

None
1596059 Resolved an issue where Series 2 bootloader applications could fail to build with the IAR toolchain when glitch mitigation was disabled. The fix aligns the bootload_verifyApplication return type with the expected interface definition. None

None

Chip Enablement#

Added in 3.3.1#

  • None

Added in 3.3.0#

None.

Application Example Changes#

New Examples | Modified Examples | Removed Examples | Deprecated Examples

New Examples#

None.

Modified Examples#

None.

Removed Examples#

None.

Deprecated Examples#

None.

Known Issues and Limitation#

Issues in 3.3.1#

ID Issue Description GitHub / Salesforce Reference (if any) Affected Software Variants, Hardware, Modes, Host Interfaces
1752568 After a full or partial application OTA DFU on the BRD4407A, the device does not advertise after reboot when built with the LLVM toolchain. The OTA transfer completes successfully, but advertising does not resume. This issue does not affect builds that use the GCC toolchain. None None
1757351 The bootloader_app_properties.slcc component does not include a documentation entry. As a result, the component does not provide the expected Help link for its public properties. None None

Issues in 3.3.0#

None.