WiSeConnect - SiWx91x Platform SDK Version 4.0.0 (Jan 22, 2026) - Release Notes#
Wi-Fi 6 + BLE (WiSeConnect) SDK Version 4.0.0
Simplicity SDK Version 2025.12.0
The SiWx91x Platform Software Development Kit (SDK) provides platform features for Silicon Labs SiWx91x microcontrollers, including peripherals, drivers, and services.
Click here for earlier releases.
Release Summary#
Key Features | API Changes | Bug Fixes | Chip Enablement
Key Features#
Enhanced the SSI peripheral driver with support for Dual and Quad modes.
Added CMake build system support for VS Code and the command line interface (CLI).
Added secure zone support for all SiWx917 applications.
API Changes#
Added APIs for the newly introduced logger feature.
Added new APIs for the following peripherals:
GPIO, USART, I2S, PCM, HSPI, SYSRTC, GPDMA, LittleFS, Clock Manager, GSPI, DMA, eFuse, Power Manager, Memory Manager, SDIO Secondary, and Logger.
Bug Fixes#
Improved stability and functionality for DMA, QEI, SSI, and RHT sensor drivers.
Enhanced DEBUGOUT macro documentation with guidance to append
\r\nfor proper terminal log output.
Chip Enablement#
None
Key Features#
New Features | Enhancements | Removed Features | Deprecated Features
Note: See Feature Matrix for a list of any applicable APIs, examples, software variants, modes, hardware, and host interfaces applicable for each feature.
New Features#
Implemented additional features for existing peripherals:
SSI Dual and Quad modes
SYSRTC
PRS
Added CMake build system support.
Added Debug Logger support in the SDK.
Enhancements#
Improved the PWM example to show dead-time insertion and added documentation for center-aligned, lead-edge, and tail-edge modes.
Updated README files for all peripheral examples with clear descriptions and better usage instructions.
Enhanced Timer documentation with improved explanations and usage details.
Added validation checks to EPIO APIs to ensure valid port and pin configurations.
Improved RAM and flash overflow detection with better linker checks and enhanced stack/heap validation.
Enhanced LittleFS example with step-by-step API usage including write and erase operations.
Updated ADC documentation with configuration steps and temperature calculation formula.
Optimized SDIO DMA performance for faster data transmission and reception.
Enhanced SDIO interrupt handler with improved event handling and GPDMA support.
Added flexible memory allocation options with a heap-specific memory manager.
Improved I2C driver with updated naming conventions.
Added clock output configuration API for consistent clock management.
Introduced
sl_si91x_i2s_deinit_v2to enhance the deinitialization process of the I2S interface.Improved component descriptions for analog peripherals (ADC, DAC, Analog Comparator, OPAMP), SSI, I2C, and ULP Timer for better clarity.
Removed Features#
None
Deprecated Features#
None
API Changes#
New APIs | Modified APIs | Removed APIs | Deprecated APIs
New APIs#
New API Signature | Deprecated API replaced by this (if any) |
|---|---|
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
Modified APIs#
None
Removed APIs#
None
Deprecated APIs#
Deprecated API Name | Planned Removal Date |
|---|---|
| 2026-06 |
| 2026-06 |
| 2026-06 |
| 2026-06 |
| 2027-06 |
| 2027-06 |
| 2027-06 |
| 2027-06 |
| 2027-06 |
| 2027-06 |
| 2027-06 |
| 2027-06 |
| 2027-06 |
| 2027-06 |
| 2027-06 |
| 2027-06 |
| 2027-06 |
Bug Fixes#
Note: See the Feature Matrix section for a list of all hardware parts that work with the WiSeConnect SDK.
| ID | Issue Description | GitHub / Salesforce Reference (if any) | Affected Software Variants, Hardware, Modes, Host Interfaces |
|---|---|---|---|
| 1463912 | Resolved issue with AES encryption with NWP power save is enabled. | None |
|
| 1497836 | Fixed SysTick timing precision issue in RTOS applications when low-power mode is disabled. | None |
|
| 1482392 | Resolved SDC maximum sampling threshold alignment to 15 and 16. | None |
|
| 1479665 | Fixed SSI application failure issue observed at lower frequencies (1 MHz/2 MHz). | None |
|
| 1479624 | Removed low configuration (less than 1ms) values for WDT manager timeout. | None |
|
| 1478520 |
Fixed UART IRQ handler issues by introducing sl_si91x_usart_multiple_instance_register_event_callback() API for improved event callback registration, adding null pointer checks, and requiring pull-up resistors to be enabled on unconnected UART Rx pins to prevent spurious interrupts.
|
None |
|
| 1476728 | Fixed structure type definitions in the Power Manager driver for accurate configuration handling. | None |
|
| 1487369 | Fixed GSPI maximum baud rate constant by updating it to 116 MHz. | None |
|
| 1504610 | Correct the uDMA instance mapping to ensure reliable UART operation when multiple UARTs are configured with DMA. | None |
|
| 1451220 | Fixed incorrect temperature and motion sensor readings on the dev kit (SiWx917-DK2605A) by resolving the ICM initialization issue and addressing the SSI DMA init hang. | None |
|
| 1475019 |
Added a usage note in the Software Reference Manual for the DEBUGOUT macro, advising developers to append \r\n to ensure logs are properly flushed to the terminal.
|
None |
|
| 1488458 | Fixed ADC FIFO example to read correct data for multiple channels by moving ping_pong_memory_read array from local to global scope and resetting it during deinit/reset. | None |
|
| 1519194 |
Reduced RAM usage by approximately 500 bytes by declaring sl_bjt_config and sl_bjt_channel_config as constant variables.
|
None |
|
| 1511613 |
Added mode validation in sl_si91x_usart_async_receive_data() to ensure that only USART instances configured in asynchronous mode can use the asynchronous receive API, preventing incorrect behavior when called in synchronous mode.
|
None |
|
| 1509195 | Fixed LittleFS component to allow flexible heap selection. Previously, LittleFS had a hard dependency on freertos_heap_4, preventing users from choosing alternative heap implementations such as Heap_5. This restriction has been removed, enabling customers to select any heap component for their projects. | None |
|
| 1424316 | Fixed GSPI transfer inefficiency by adding a blocking API to improve byte-transfer performance. | None |
|
| 1525464 | Fixed WiseConnect WDT Manager causing immediate watchdog reset when compiled with GCC optimization level -Og by explicitly initializing configuration variables. | None |
|
| 1543056 | Fixed SDIO Secondary callback to correctly trigger HOST_INTR_SEND_EVENT by handling SEND and CMD52 events. | None |
|
| 1542490 | Fixed ADC sampling rate being set incorrectly for sampling rates of 76Hz or below in SL_ADC_FIFO_MODE and ULP_ADC examples. | None |
|
| 1534303 | Fixed PSRAM linker file to prevent NOLOAD sections from occupying binary space by removing default .text and .data dependencies. | None |
|
| 1532873 | Fixed I2S clock frequency issue for 24-bit, 8 kHz resolution by calculating and applying a custom division factor instead of using fixed PLL values. | None |
|
| 1511606 | Resolved issue in HSPI Primary mode where data transfer completion events are not triggered while verifying deinit functionality when TEST_MEMORY_READ_WRITES is enabled. | None |
|
| 1529088 | Fixed PSRAM Software Components display in UI to hide unsupported configuration (HEAP, BSS, and STACK) options. These options have been hidden to prevent runtime failures. | None |
|
| 1488092 | Fixed incorrect visibility of BRD4338A radio board component in Simplicity Studio. The visibility has been set to "none" to hide this component from the UI, preventing unintended modifications by users. | None |
|
| 1489303 | Fixed an issue where writing calibration data to common flash caused the M4 to hang when the power manager was enabled. | None |
|
| 1514940 | Fixed hang issue during initialization when firmware fallback component and M4 power save were both enabled in the application. | None |
|
| 1437906 | Fixed issue where BOD (Brown-Out Detection) interrupt was triggered at 1.9 V instead of the documented minimum threshold voltage of 1.75 V as specified in the SiWx917 Family Reference Manual. | None |
|
| 1492363 | Fixed an issue in the Pin Tool that prevented GPIO mode pin configurations from generating the correct macros for SDK usage. These pins are now correctly translated into macros compatible with the SDK. | None |
|
| 1475668 | Fixed configuration validation to prevent errors when selecting three OPAMPs in Cascaded Inverting PGA, Cascaded Non-Inverting PGA, or two OPAMPs Differential Amplifier modes. These modes now correctly enforce the requirement to select exactly two OPAMPs. | None |
|
| 1504651 | Fixed voltage drop issue when using GPIO_29 as VinP input for OPAMP3 Trans-Impedance Amplifier with current source input. | None |
|
| 1504649 | Fixed voltage drop issue when using GPIO_27 or DAC as VinP input for OPAMP1 Trans-Impedance Amplifier with current source input. | None |
|
| 1500145 | Fixed issue where output voltage exceeded OPAMP Reference Voltage (2.5 V) when R1=R2=20K for Instrumentation Amplifier configuration. | None |
|
| 1438016 | Fixed issue where BOD (Brown-Out Detection) was non-functional in ULP power state PS2. | None |
|
| 1455245 | Blackout reset fails to occur on module board SiW917Y-RB4343A Rev. A07. | None |
|
| 1364360 |
Fixed issue where Simplicity Studio's "Add New Instance" feature for peripherals with multiple instances suggested default instance names (e.g., inst0, inst1) that differed from the instance names supported in the reference documentation and application examples. Instance naming has been aligned with peripheral-specific documentation conventions. |
None |
|
| 1417168 | Fixed issue where PSA components were not visible in the Simplicity Studio GUI, preventing users from adding security modules to their projects. Both mbedTLS and SI91X-PSA driver components are now properly displayed alongside PSA components. | None |
|
| 1496318 | Fixed issue where DUT hang was observed during firmware download over TCP OTA when using the firmware fallback feature. | None |
|
| 1483509 | Fixed issue where the NWP firmware fallback feature required the default slot image to be set using the sl_si91x_select_default_nwp_fw API before calling sl_net_init. The API now automatically handles default slot selection. | None |
|
| 1462701 | Fixed issue where erasing an inactive image slot would take approximately 14 seconds, during which wireless tasks were blocked, potentially causing AP disconnection and protocol disruptions. | None |
|
| 1513362 |
Updated Power Save pin nomenclature to align with NCP data sheet conventions. In NCP Power Save Examples with EFR32 host, Power Save pins (UULP_VBAT_GPIO_0 and UULP_VBAT_GPIO_2) are now properly configured to enable correct SiWx917 wake-up and sleep operation in GPIO-Based Power Save Mode-2. |
None |
|
| 1476840 |
Replaced manual millisecond-to-tick conversions with SLI_SYSTEM_MS_TO_TICKS macro for accurate OS delays.
|
None |
|
| 1517330 |
Fixed sl_si91x_set_nwp_config_request() API error; host can now configure XTAL/PMU good time prior to sl_net_init().
|
None |
|
Chip Enablement#
None
Application Example Changes#
New Examples | Modified Examples | Removed Examples | Deprecated Examples
Note: See the Feature Matrix section for a list of all hardware parts that work with the WiSeConnect SDK.
New Examples#
SL Si91x - SL_LOGGER_EXAMPLE- Demonstrates the logger service on the SiWx917 SoC device.SL Si91x - WDT Manager- Demonstrates the Watchdog Timer Manager service on the SiWx917 SoC device.
Modified Examples#
None
Removed Examples#
CPC Secondary SDIO with Security- This example has been removed as it is no longer maintained in Simplicity SDK.SL Si91x - Watchdog Timer- This example has been replaced bySL Si91x - WDT Manager, which provides enhanced watchdog timer management capabilities.
Deprecated Examples#
None
Known Issues and Limitations#
Note: See the Feature Matrix section for a list of all hardware parts that work with the WiSeConnect SDK.
| ID | Issue or Limitation Description | GitHub / Salesforce Reference (if any) | Workaround (if any) | Affected Software Variants, Hardware, Modes, Host Interfaces |
|---|---|---|---|---|
| N/A | FreeRTOS tick-less idle mode is currently not supported in the Sensor Hub example application. | None | None |
|
| N/A | UART instances do not support different FIFO thresholds. | None | None |
|
| 1475241 | SDC cannot be used with OPAMP as its input. | None | None |
|
| N/A | The ULP Timer may experience timer drifts due to the inaccuracy of the clock source (RC oscillator). | None | None |
|
| 1527571 | PSRAM access with Data Cache enabled may experience performance degradation ranging from 2× to 9× depending on memory access patterns and workload characteristics. This is due to software-based mitigation implemented to fix a data corruption issue during write-after-read sequences. A detailed user guide outlining the affected use cases, recommended access patterns, and performance trade-offs will be released in subsequent releases. | None | None |
|
| N/A | Peripheral clock sources are currently fixed and cannot be configured by the user. | None | None |
|
| N/A | GPDMA driver currently supports only memory-to-memory transfers. | None | None |
|
| N/A | I2C receive operations using DMA may fail because the IC DATA CMD register must be programmed with a read command for each byte. Using two DMA channels—one for programming the register and one for data transfer—can lead to synchronization issues due to DMA flow control delays. | None | None |
|
| 1567865 | SSI Dual and Quad mode supports address lengths up to 32 bits only. | None | None |
|
| N/A | The DMA controller does not support timeout or threshold interrupts for half-full or full states. For asynchronous transactions, the application must implement handshaking mechanisms to ensure proper synchronization and data transfer control. | None | None |
|
| N/A | Only a few wakeup sources (ULP GPIO, ULP Timer, ULP ADC, ULP Comparator, and ULP UART) are currently supported for the PS1 state in the Power Manager. | None | None |
|
| 1574418 |
Using slc generate --toolchain gcc or slc generate --with toolchain_gcc may fail with exclusivity errors due to the wiseconnect_toolchain_gcc_standard component incorrectly providing toolchain_gcc, resulting in a conflict with the SiSDK toolchain_gcc component. If using those two command line options results in exclusivity errors, then you can remove them, and note that in a future WiseConnect release, you might have to reintroduce the toolchain option on the command line. Refer to future WiseConnect release notes for updates on possible behavior changes.
|
None | None |
|