CASTLE 2.0 is released

NCMV — Sat, 12 Sep 2026 11:43:51 +0000

Continue from the development of CASTLE library version 1.0: https://dev.to/nguyenchiemminhvu/castle-a-modern-c-template-library-for-safety-critical-embedded-systems-5hjk

I would like to introduce about prototype version 2.0:

nguyenchiemminhvu / castle

Compliant Automotive Safety Template Library for Embedded

CASTLE

Compliant Automotive Safety Template Library for Embedded

Prototype version 2.0

CASTLE is a lightweight, header-only CPP17-based template library built for safety-critical embedded systems where every byte of RAM, every millisecond of jitter, and every allocation counts. It is inspired by the ETL (Embedded Template Library) and is intended as a drop-in replacement for parts of the C++ standard library and common enterprise frameworks that are otherwise unsuitable for automotive ECUs MCUs, and other resource-constrained targets.

The main idea is simple: make common C++ jobs easier without bringing the runtime costs that are often unwanted on small targets.

CASTLE 2.0 focuses on:

deterministic, fixed-capacity behavior where practical
no mandatory heap allocation
no mandatory RTTI
no mandatory exceptions
no virtual functions in the core data structures
no dependency on the C++ STL
C++17 and lower language levels
GCC, Clang, and ARM compiler families

CASTLE is a good fit for firmware, device…

View on GitHub

CASTLE – A modern C++ template library for safety-critical embedded systems

NCMV — Sat, 05 Sep 2026 16:52:47 +0000

https://github.com/nguyenchiemminhvu/castle

I’ve been working on CASTLE — Compliant Automotive Safety Template Library for Embedded.

The name is intentional: the library was originally motivated by a simple goal — building small, predictable C++ building blocks for automotive and other safety-critical embedded systems.

CASTLE is a prototype C++17, header-only library built around a few embedded-friendly constraints:

no heap allocation
no exceptions or RTTI
fixed-capacity, statically bounded data structures
predictable resource usage
compile-time configuration where practical
lightweight, composable components

It currently includes fixed-capacity buffers, callbacks, event and signal dispatching, timers, logging, iterators, bit utilities, safe numeric casts, and other small utilities.

CASTLE was inspired by the Embedded Template Library (ETL), but takes a somewhat different approach, focusing on a more modern C++ coding style and more expressive APIs. In particular, I’m exploring more convenient ways to build event-driven embedded software while keeping memory usage bounded and behaviour predictable.

This is still a prototype, so I’m sharing it mainly to get feedback from people working with embedded C++, automotive software, or safety-critical systems.

Planned additions include fixed-capacity containers, finite state machines, protocol I/O, encoders/decoders, CRC and checksum algorithms, and more compile-time configuration for event-driven systems...

I’d particularly like to hear where you think this approach makes sense, where it doesn’t, and what would make CASTLE more useful in a real embedded project.

DEV Community: NCMV

CASTLE 2.0 is released

nguyenchiemminhvu / castle

Compliant Automotive Safety Template Library for Embedded

CASTLE

CASTLE – A modern C++ template library for safety-critical embedded systems