The Chiisai Open-Source Specification Simplifies HAL Development on Small Microcontrollers

Open-Source Specification The Chiisai Open-Source Specification Simplifies HAL Development on Small Microcontrollers

2026-09-14 By Stefanie Eckardt | Translated by AI 1 min Reading Time

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With Chiisai, Vector, in collaboration with Infineon Technologies, is releasing an open and royalty-free specification that fundamentally simplifies the development of hardware abstraction layers on small microcontrollers. The specification focuses on essential basic functions, thereby reducing the software footprint. It also supports the efficient use of resource-constrained microcontrollers.

The open Chiisai standard supports the cross-vendor development of HALs, middleware, and embedded software for small microcontrollers.(Image: Vector Informatics) — The open Chiisai standard supports the cross-vendor development of HALs, middleware, and embedded software for small microcontrollers.
(Image: Vector Informatics)

Chiisai is specifically designed for microcontrollers with limited resources, such as those typically used in sensors, actuators, and other embedded systems. The specification defines standardized interfaces for relevant basic and communication functions and clearly separates drivers from middleware. This makes it easier to reuse software components across different hardware platforms.

The goal is to standardize the development of hardware abstraction layers (HAL) on small microcontrollers in a practical, efficient, and vendor-neutral manner. Infineon played a key role in the development of Chiisai. The company’s primary contribution was tailoring the specification specifically to small microcontrollers. Other semiconductor manufacturers, such as Microchip Technology, are also already actively supporting the standard and are jointly driving the development of an open, vendor-neutral software ecosystem.

An Open Standard for a Rapidly Growing Software Ecosystem

The new specification provides an open standard that simplifies the development of vendor-neutral HALs. The specification significantly lowers the barriers to entry, enabling the rapid development of custom HALs and their use by various middleware solutions, regardless of the microcontroller or hardware manufacturer. This creates a growing, cross-vendor ecosystem that promotes interoperability, reduces integration effort, and facilitates collaboration between automakers, suppliers, and semiconductor manufacturers. As a result, companies across the entire value chain benefit from significantly easier access to modern embedded and SDV-related software stacks.

Full Compatibility with Microsar IO

The interfaces of Vector’s new software base layer, Microsar IO, are fully compatible with the Chiisai specification. As soon as a Chiisai-compliant HAL is available for a microcontroller, Microsar IO can be deployed on that hardware platform without any additional modifications. Microsar IO is just one of many middleware solutions that can be built on top of a Chiisai-based HAL.

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