Keil ARM compiler vs GCC ARM compiler

The Keil MDK (Microcontroller Development Kit) and the GCC Compiler for ARM are both widely used tools for developing embedded applications, particularly for ARM Cortex-M microcontrollers. However, they differ significantly in terms of licensing, features, usability, and target audiences. Below is a detailed comparison of Keil MDK 5.28 and the GCC Compiler for ARM.

1. Overview

Keil MDK 5.28

Vendor : Keil (owned by ARM Holdings).
Type : Proprietary, commercial IDE and toolchain.
Target Audience : Professional developers and companies working on ARM-based embedded systems.
Version : MDK 5.28 includes an integrated development environment (IDE), compiler, debugger, and middleware libraries.
Licensing : Free version available with limited code size (32 KB). Full functionality requires a paid license.
You can download Keil ARM compiler v5.28 from the link below
Download Keil ARM compiler v5.28

GCC Compiler for ARM

Vendor : GNU Project (community-driven).
Type : Open-source, cross-platform compiler toolchain.
Target Audience : Developers who prefer open-source tools or need flexibility across platforms.
Version : Part of the GNU Arm Embedded Toolchain (e.g., arm-none-eabi-gcc).
Licensing : Fully free and open-source under the GNU General Public License (GPL).

2. Key Differences

Licensing	Proprietary (free version limited to 32 KB)	Open source (completely free)
IDE Integration	Integrated IDE (µVision)	No IDE; works with external IDEs (e.g., VS Code, Eclipse)
Ease of Use	Beginner-friendly GUI	Requires manual setup and familiarity with CLI
Optimization	Highly optimized for ARM Cortex-M	General-purpose optimization
Middleware Libraries	Includes CMSIS, RTX RTOS, and other libraries	No built-in middleware; must be added manually
Debugging Tools	Built-in debugger (supports JTAG/SWD)	Requires external tools (e.g., OpenOCD, GDB)
Code Size Limit	Free version limited to 32 KB	No code size limit
Platform Support	Windows only	Cross-platform (Windows, macOS, Linux)
Customizability	Limited customization	Highly customizable
Community vs Vendor Support	Official support from ARM/Keil	Community-driven support

3. Detailed Comparison

3.1 Licensing and Cost

Keil MDK :
- The free version has a 32 KB code size limit , which is sufficient for small projects but restrictive for larger ones.
- A full license can cost several hundred dollars, depending on the edition and features.
- Suitable for professional environments where official support and advanced features are required.
GCC Compiler :
- Completely free and open-source.
- No code size restrictions, making it ideal for large-scale projects.
- Suitable for hobbyists, students, and developers who prefer open-source tools.

3.2 IDE and Usability

Keil MDK :
- Provides the µVision IDE , which is user-friendly and beginner-friendly.
- Offers a graphical interface for project creation, configuration, debugging, and flashing.
- Includes wizards and templates for quick setup.
- Debugging is seamless with integrated support for JTAG and SWD interfaces.
GCC Compiler :
- Does not come with an IDE by default. Developers often use external IDEs like VS Code , Eclipse , or PlatformIO .
- Requires familiarity with command-line tools (e.g., make, gcc, gdb) and scripting (e.g., Makefiles).
- Debugging requires additional tools like OpenOCD and GDB .

3.3 Optimization and Performance

Keil MDK :
- The ARM Compiler (part of MDK) is specifically optimized for ARM Cortex-M processors.
- Produces highly efficient machine code, often resulting in smaller binaries and faster execution compared to GCC.
- Includes advanced optimization options tailored for embedded systems.
GCC Compiler :
- While GCC is highly capable, its optimizations are more generic and not as fine-tuned for ARM Cortex-M as the ARM Compiler.
- May produce slightly larger binaries or less efficient code compared to Keil's compiler.
- Still performs well for most applications, especially when configured correctly.

3.4 Middleware and Libraries

Keil MDK :
- Includes CMSIS (Cortex Microcontroller Software Interface Standard) libraries for hardware abstraction.
- Provides middleware such as RTX RTOS , USB stacks , TCP/IP stacks , and file systems .
- Simplifies development by offering pre-built libraries and examples.
GCC Compiler :
- Does not include any middleware by default.
- Developers must manually integrate third-party libraries (e.g., FreeRTOS, FatFS) or write their own implementations.
- More flexible but requires additional effort for complex projects.

3.5 Debugging Tools

Keil MDK :
- Integrated debugging tools with support for JTAG and SWD interfaces.
- Includes advanced debugging features like breakpoints, watchpoints, memory inspection, and real-time variable monitoring.
- Works seamlessly with ST-LINK, J-Link, and other debug probes.
GCC Compiler :
- Requires external debugging tools like OpenOCD or PyOCD .
- Debugging is typically done using GDB (GNU Debugger) .
- Setup can be more complex and less intuitive compared to Keil's integrated tools.

3.6 Platform Support

Keil MDK :
- Only supports Windows operating systems.
- Not suitable for developers using macOS or Linux.
GCC Compiler :
- Fully cross-platform, supporting Windows , macOS , and Linux .
- Ideal for developers who prefer non-Windows environments.

3.7 Customizability

Keil MDK :
- Limited customization options for the build process.
- Configuration is primarily done through the µVision GUI.
GCC Compiler :
- Highly customizable, allowing developers to tweak every aspect of the build process (e.g., compiler flags, linker scripts, optimization levels).
- Suitable for advanced users who need fine-grained control over their projects.

4. When to Choose Each Tool

Choose Keil MDK if:

You need an easy-to-use, beginner-friendly IDE .
You are working on a professional project that requires official support and advanced features.
You want access to middleware libraries (e.g., RTOS, USB stacks) out of the box.
Your project is relatively small and fits within the 32 KB free code size limit (or you have a budget for a paid license).
You are using Windows as your development environment.

Choose GCC Compiler if:

You prefer open-source tools and want complete control over your development environment.
You are working on a large-scale project that exceeds the 32 KB limit of Keil's free version.
You need cross-platform support (Windows, macOS, Linux).
You are comfortable with command-line tools and configuring build systems manually.
You want to avoid licensing costs.

5. Conclusion

Both Keil MDK 5.28 and the GCC Compiler for ARM are excellent tools for ARM Cortex-M development, but they cater to different audiences and use cases:

Keil MDK is ideal for professional developers who value ease of use, official support, and integrated middleware libraries.
GCC Compiler is better suited for developers who prioritize flexibility, open-source tools, and cross-platform compatibility.

Ultimately, the choice depends on your specific needs, budget, and familiarity with embedded development tools. Many developers also use a combination of both tools, leveraging the strengths of each depending on the project requirements.