
Nikodem Kastelik developed and maintained embedded firmware and driver features across NordicBuilder/sdk-nrf, AmbiqMicro/ambiqzephyr, and nrfconnect/sdk-zephyr, focusing on hardware abstraction, power management, and cross-platform compatibility. He integrated NRFX driver upgrades, optimized RAM retention and power consumption, and enhanced test reliability by refining build systems and device tree configurations. Using C, CMake, and Zephyr RTOS, Nikodem addressed low-level issues such as I2C driver stability, memory management, and secure boot workflows. His work demonstrated a deep understanding of embedded systems, consistently improving hardware integration, reducing technical debt, and ensuring robust, maintainable codebases for evolving Nordic and Zephyr platforms.
March 2026 monthly summary for nxp-upstream/zephyr focused on stabilizing SAADC behavior for the nRF53 platform by applying nrfx fixes and related build-time adjustments. This work enhances reliability of the SAADC peripheral in upstream code, reduces risk in downstream firmware, and lays groundwork for future Nordic SoC compatibility across Zephyr.
March 2026 monthly summary for nxp-upstream/zephyr focused on stabilizing SAADC behavior for the nRF53 platform by applying nrfx fixes and related build-time adjustments. This work enhances reliability of the SAADC peripheral in upstream code, reduces risk in downstream firmware, and lays groundwork for future Nordic SoC compatibility across Zephyr.
February 2026 (Month: 2026-02) – Focused maintenance and reliability work in the nrfconnect/sdk-nrf repository. Delivered a targeted RAM power-down fix in the test suite to ensure all RAM blocks are properly powered after test execution, preventing cascading failures for subsequent tests on the same board. This work strengthens CI reliability, reduces flaky test runs, and provides a stable foundation for upcoming feature work.
February 2026 (Month: 2026-02) – Focused maintenance and reliability work in the nrfconnect/sdk-nrf repository. Delivered a targeted RAM power-down fix in the test suite to ensure all RAM blocks are properly powered after test execution, preventing cascading failures for subsequent tests on the same board. This work strengthens CI reliability, reduces flaky test runs, and provides a stable foundation for upcoming feature work.
January 2026 performance snapshot focused on reliability, compatibility, and security integrations across Zephyr and Nordic SDKs. Delivered boot chain stabilization, NFC stack robustness, and API-aligned cryptography hardware support. Key outcomes include GPPI/bootloader cleanup to harden boot transitions, NRFX NRFX 4.1-compatible TRNG driver integration, and device-tree updates for NRF54LV10A, improving hardware compatibility and forward-compatibility for customers.
January 2026 performance snapshot focused on reliability, compatibility, and security integrations across Zephyr and Nordic SDKs. Delivered boot chain stabilization, NFC stack robustness, and API-aligned cryptography hardware support. Key outcomes include GPPI/bootloader cleanup to harden boot transitions, NRFX NRFX 4.1-compatible TRNG driver integration, and device-tree updates for NRF54LV10A, improving hardware compatibility and forward-compatibility for customers.
December 2025 monthly summary focusing on reliability, test coverage, and documentation across two Nordic SDK repositories. Delivered key features, bug fixes, and migration docs to reduce field risk and improve upgrade paths. Highlights include: (1) enhanced runtime stability for PWM driver suspend/resume by avoiding unintended nrfx state zeroing, (2) corrected reset reason reporting for nRF5340 Network, (3) expanded I2C/TWI verification coverage for NRF52, and (4) updated 4.0.1 migration guide and documentation. These efforts reduce field risk, improve debugging visibility, and accelerate safe upgrades. Demonstrated proficiency in Zephyr integration, nrfx runtime state management, hardware information handling, test variant development, and technical documentation.
December 2025 monthly summary focusing on reliability, test coverage, and documentation across two Nordic SDK repositories. Delivered key features, bug fixes, and migration docs to reduce field risk and improve upgrade paths. Highlights include: (1) enhanced runtime stability for PWM driver suspend/resume by avoiding unintended nrfx state zeroing, (2) corrected reset reason reporting for nRF5340 Network, (3) expanded I2C/TWI verification coverage for NRF52, and (4) updated 4.0.1 migration guide and documentation. These efforts reduce field risk, improve debugging visibility, and accelerate safe upgrades. Demonstrated proficiency in Zephyr integration, nrfx runtime state management, hardware information handling, test variant development, and technical documentation.
Month 2025-11 highlights: two high-impact fixes and feature upgrade across Nordic platforms. Delivered a Nordic HAL compatibility upgrade to nrfx 4.0.1 for zephyrproject-rtos/trusted-firmware-m, and fixed a peripheral initialization assertion to support nrfx 4.0 error handling in nrfconnect/sdk-nrf. These changes improve platform compatibility, reduce runtime failures, and accelerate adoption of the latest Nordic features. Demonstrated strong cross-repo collaboration, code quality (commit signing), and a focus on business value through stability and maintainability gains.
Month 2025-11 highlights: two high-impact fixes and feature upgrade across Nordic platforms. Delivered a Nordic HAL compatibility upgrade to nrfx 4.0.1 for zephyrproject-rtos/trusted-firmware-m, and fixed a peripheral initialization assertion to support nrfx 4.0 error handling in nrfconnect/sdk-nrf. These changes improve platform compatibility, reduce runtime failures, and accelerate adoption of the latest Nordic features. Demonstrated strong cross-repo collaboration, code quality (commit signing), and a focus on business value through stability and maintainability gains.
October 2025: Delivered major cross-repo NRFX upgrade and GPIOTE alignment, enhanced Bluetooth time synchronization, and optimization of test footprint. Upgraded NRFX to 4.0.1 across sdk-nrf and sdk-zephyr, enabling device-tree integration and errno-based error codes. Refactored GPIOTE integration across multiple components to align with nrfx changes (driver, sample, tests), replacing const-based instances with pointer access. Implemented test optimizations reducing flash usage by disabling unnecessary GPIO interrupts in mcuboot external flash tests. Fixed errno handling in audio PDM loopback timer init and I2C latency tests. Result: improved stability, predictability of builds, faster/cheaper tests, and clearer error reporting.
October 2025: Delivered major cross-repo NRFX upgrade and GPIOTE alignment, enhanced Bluetooth time synchronization, and optimization of test footprint. Upgraded NRFX to 4.0.1 across sdk-nrf and sdk-zephyr, enabling device-tree integration and errno-based error codes. Refactored GPIOTE integration across multiple components to align with nrfx changes (driver, sample, tests), replacing const-based instances with pointer access. Implemented test optimizations reducing flash usage by disabling unnecessary GPIO interrupts in mcuboot external flash tests. Fixed errno handling in audio PDM loopback timer init and I2C latency tests. Result: improved stability, predictability of builds, faster/cheaper tests, and clearer error reporting.
Month 2025-09 focused on stabilizing the I2C subsystem for Nordic platforms within Zephyr and improving cross-platform compatibility. Delivered a targeted bug fix to restore memory region property checker macro functionality for the nRF TWIS I2C driver, enhancing reliability and maintainability of the driver codebase.
Month 2025-09 focused on stabilizing the I2C subsystem for Nordic platforms within Zephyr and improving cross-platform compatibility. Delivered a targeted bug fix to restore memory region property checker macro functionality for the nRF TWIS I2C driver, enhancing reliability and maintainability of the driver codebase.
August 2025: Delivered targeted debugging and maintenance improvements in zephyr-testing. Implemented Serial Wire Output (SWO) support for Nordic nRF54L SoCs to accelerate debugging and development workflows. Upgraded Nordic HAL and nrfx dependencies (nrfx 3.14.0; MDK 8.72.2) to improve device compatibility and stability with the latest hardware. These changes reduce debugging time, broaden device coverage, and strengthen platform readiness for upcoming Nordic updates.
August 2025: Delivered targeted debugging and maintenance improvements in zephyr-testing. Implemented Serial Wire Output (SWO) support for Nordic nRF54L SoCs to accelerate debugging and development workflows. Upgraded Nordic HAL and nrfx dependencies (nrfx 3.14.0; MDK 8.72.2) to improve device compatibility and stability with the latest hardware. These changes reduce debugging time, broaden device coverage, and strengthen platform readiness for upcoming Nordic updates.
July 2025 monthly summary: Delivered hardware interface improvements and stability fixes across AmbiqMicro/ambiqzephyr and zephyrproject-rtos/zephyr-testing. Key work included (1) Nordic HAL and NRFX 3.13.0 integration, updating the west manifest and MDK 8.72.1 for current Nordic device support; (2) SAADC driver simplification for nRF54LV10A by removing VDD/DVDD inputs and adjusting saadc_psels sizing to MDK 8.72.1 behavior; (3) Comparator VDD-reference fallback to an internal 1.2V reference for No-VDD hardware to ensure reliable operation when VDD references are unavailable; (4) SPI driver robustness improvement by correcting buffer cleanup on transfer preparation errors, preventing memory leaks or corruption. Overall, these changes reduce configuration fragility, improve reliability and cross-device compatibility, and deliver tangible business value through more robust drivers and safer memory handling.
July 2025 monthly summary: Delivered hardware interface improvements and stability fixes across AmbiqMicro/ambiqzephyr and zephyrproject-rtos/zephyr-testing. Key work included (1) Nordic HAL and NRFX 3.13.0 integration, updating the west manifest and MDK 8.72.1 for current Nordic device support; (2) SAADC driver simplification for nRF54LV10A by removing VDD/DVDD inputs and adjusting saadc_psels sizing to MDK 8.72.1 behavior; (3) Comparator VDD-reference fallback to an internal 1.2V reference for No-VDD hardware to ensure reliable operation when VDD references are unavailable; (4) SPI driver robustness improvement by correcting buffer cleanup on transfer preparation errors, preventing memory leaks or corruption. Overall, these changes reduce configuration fragility, improve reliability and cross-device compatibility, and deliver tangible business value through more robust drivers and safer memory handling.
June 2025 monthly summary: Delivered core Nordic HAL and ADC improvements for AmbiqZephyr, strengthening hardware compatibility, stability, and performance across Nordic-based boards.
June 2025 monthly summary: Delivered core Nordic HAL and ADC improvements for AmbiqZephyr, strengthening hardware compatibility, stability, and performance across Nordic-based boards.
May 2025 monthly summary for AmbiqMicro/ambiqzephyr. Focused on simplifying configuration by removing an obsolete nRF54L workaround, aligning with MDK 8.69.1 (nrfx 3.10). No behavioral changes introduced; the change reduces maintenance burden and technical debt, and improves code cleanliness.
May 2025 monthly summary for AmbiqMicro/ambiqzephyr. Focused on simplifying configuration by removing an obsolete nRF54L workaround, aligning with MDK 8.69.1 (nrfx 3.10). No behavioral changes introduced; the change reduces maintenance burden and technical debt, and improves code cleanliness.
In April 2025, the NordicBuilder/sdk-nrf team focused on validating power consumption when the nRF54L Errata 30 workaround is active. A dedicated test was added to measure current draw to ensure the workaround does not introduce unintended power consumption, strengthening power integrity for low-power devices and reducing regression risk. The work is traceable to a single commit in the repo that adds the test, supporting reproducibility and future maintenance.
In April 2025, the NordicBuilder/sdk-nrf team focused on validating power consumption when the nRF54L Errata 30 workaround is active. A dedicated test was added to measure current draw to ensure the workaround does not introduce unintended power consumption, strengthening power integrity for low-power devices and reducing regression risk. The work is traceable to a single commit in the repo that adds the test, supporting reproducibility and future maintenance.
February 2025 monthly summary: Focused on NRFX 3.10.0 alignment and cross-device compatibility for Nordic platforms. Delivered codebase cleanup and manifest synchronization to align with nrfx 3.10 and Zephyr releases, and implemented conditional builds to prevent errors on unsupported hardware. Result: reduced build errors, broader device support, and cleaner dependency alignment across two repos. Key technologies: C, Zephyr RTOS, MPC OWNERID, conditional compilation; traceable changes across commits.
February 2025 monthly summary: Focused on NRFX 3.10.0 alignment and cross-device compatibility for Nordic platforms. Delivered codebase cleanup and manifest synchronization to align with nrfx 3.10 and Zephyr releases, and implemented conditional builds to prevent errors on unsupported hardware. Result: reduced build errors, broader device support, and cleaner dependency alignment across two repos. Key technologies: C, Zephyr RTOS, MPC OWNERID, conditional compilation; traceable changes across commits.
January 2025: Delivered two high-value Nordic-enabled features for telink-semi/zephyr, strengthening platform support and reliability while laying groundwork for longer-term uptime on Nordic SoCs. Key outcomes include: (1) NRFX 3.10.0 integration enabling nRF7120 Eng A, with RAM control configuration reflected in Kconfig and a cleanup of redundant RAM-disabling code; (2) Retained memory support for the nRF5340 DK, including driver/config/overlay updates, new test YAML, and RAM retention enabled in system-off via a dedicated device-tree overlay. Stabilized operation through targeted fixes to the clock control path by ignoring unused XOTUNE events. Business value: expanded Nordic support, reduced runtime risk, improved power efficiency, and ready-made foundation for extended uptime in production devices.
January 2025: Delivered two high-value Nordic-enabled features for telink-semi/zephyr, strengthening platform support and reliability while laying groundwork for longer-term uptime on Nordic SoCs. Key outcomes include: (1) NRFX 3.10.0 integration enabling nRF7120 Eng A, with RAM control configuration reflected in Kconfig and a cleanup of redundant RAM-disabling code; (2) Retained memory support for the nRF5340 DK, including driver/config/overlay updates, new test YAML, and RAM retention enabled in system-off via a dedicated device-tree overlay. Stabilized operation through targeted fixes to the clock control path by ignoring unused XOTUNE events. Business value: expanded Nordic support, reduced runtime risk, improved power efficiency, and ready-made foundation for extended uptime in production devices.
December 2024: Benchmark realism improvements and targeted bug fix under SPIM120 power management for NordicBuilder/sdk-nrf. Primary work focused on aligning benchmark expectations with real hardware behavior rather than introducing new features, improving the reliability and actionability of performance metrics.
December 2024: Benchmark realism improvements and targeted bug fix under SPIM120 power management for NordicBuilder/sdk-nrf. Primary work focused on aligning benchmark expectations with real hardware behavior rather than introducing new features, improving the reliability and actionability of performance metrics.
November 2024 performance highlights across kholia/zephyr and NordicBuilder/sdk-nrf: delivered reliability fixes for the NRF54L DCDC regulator, optimized RAM retention behavior in System OFF for the nRF54L15, and centralized RAM retention management with test alignment. These changes reduce energy consumption, increase hardware reliability, and simplify maintenance across two repositories.
November 2024 performance highlights across kholia/zephyr and NordicBuilder/sdk-nrf: delivered reliability fixes for the NRF54L DCDC regulator, optimized RAM retention behavior in System OFF for the nRF54L15, and centralized RAM retention management with test alignment. These changes reduce energy consumption, increase hardware reliability, and simplify maintenance across two repositories.
In Oct 2024, focused on security and stability enhancements for Nordic SDKs and Zephyr targeting the nRF54L family, delivering APPROTECT integration and a DCDC regulator fix. Key features delivered include updating the manifest to newer sdk-zephyr and TF-M revisions to enable APPROTECT for nRF54L15, aligning Zephyr SDK configuration with nRF54L15 requirements, and updating TF-M to exclude incompatible runtime APPROTECT code. Major bug fixed includes correcting the DCDC regulator configuration to ensure stable operation across hardware revisions and secure boot environments. Commit references for traceability include 5feb1ecb7a79ce1b73f247dee12c8ee079a211cc and b7fb1012b02aeb74db34e36d4446664e5922b663. Overall impact includes strengthened security posture, improved reliability of secure-boot workflows, reduced risk of runtime incompatibilities, and a clearer upgrade path for future APPROTECT deployments. Technologies and skills demonstrated include embedded firmware development, secure boot architectures (APPROTECT), Zephyr RTOS configuration, TF-M integration, manifest management, and cross-repo collaboration across NordicBuilder/sdk-nrf and kholia/zephyr.
In Oct 2024, focused on security and stability enhancements for Nordic SDKs and Zephyr targeting the nRF54L family, delivering APPROTECT integration and a DCDC regulator fix. Key features delivered include updating the manifest to newer sdk-zephyr and TF-M revisions to enable APPROTECT for nRF54L15, aligning Zephyr SDK configuration with nRF54L15 requirements, and updating TF-M to exclude incompatible runtime APPROTECT code. Major bug fixed includes correcting the DCDC regulator configuration to ensure stable operation across hardware revisions and secure boot environments. Commit references for traceability include 5feb1ecb7a79ce1b73f247dee12c8ee079a211cc and b7fb1012b02aeb74db34e36d4446664e5922b663. Overall impact includes strengthened security posture, improved reliability of secure-boot workflows, reduced risk of runtime incompatibilities, and a clearer upgrade path for future APPROTECT deployments. Technologies and skills demonstrated include embedded firmware development, secure boot architectures (APPROTECT), Zephyr RTOS configuration, TF-M integration, manifest management, and cross-repo collaboration across NordicBuilder/sdk-nrf and kholia/zephyr.

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