IAR Embedded Workbench for Renesas RX

Complete development toolchain to create smaller, faster, smarter code for all RX devices.


User-friendly IDE

Integrated development environment with project management tools and editor. Included is linker and library tools, configuration files for all devices in the RX family, example projects and code templates as well as Renesas FIT integration.


Powerful build tools

IAR C/C++ Compiler is a highly optimizing C and C++ compiler for RX. It offers a relocating RX assembler and run-time libraries, and is compliant with Renesas RX ABI and the ISO/IEC 9899:1999 standard.


Comprehensive debugger

The C-SPY Debugger is a comprehensive debugger with RX simulator, support for RTOS-aware debugging on hardware, timeline visualizing power consumption, call stack and interrupt activity as well as oower debug support with power profiling.


Integrated code analysis

IAR Embedded Workbench for RX provides integrated code analysis through the add-on for static analysis C-STAT, ensuring code quality as well as proving alignment with standards such as MISRA C:2012. In addition, the add-on product C-RUN featuring runtime analysis is also available.

Latest releases

We are constantly updating and refining our tools with new features, new device support and extended capabilities.

Latest version: 4.20

C-STAT enhancements

  • MISRA C:2012 Amendment 1
    The static analysis tool C-STAT has extended its coverage of the MISRA C:2012 Coding Standard and now fully supports MISRA C:2012 Amendment 1. This amendment adds 14 additional rules to MISRA C:2012 with a focus on security concerns highlighted by the ISO C Secure Guidelines. Several of these address specific issues pertaining to the use of untrustworthy data, a well-known security vulnerability.
  • Extended coverage of CERT C
    The static analysis tool C-STAT has extended its coverage of the SEI CERT C Coding Standard. The SEI CERT C Coding Standard's goal is to provide rules for developing safe, reliable, and secure systems in the C programming language, with support for C11 constructs. C-STAT covers all rules in the different CERT C sections listed on the CERT C wiki as of January 2020, with the exception of the API, CON, POS, and WIN sections, which are not applicable to IAR Systems products, yielding a total of 90 covered rules.
  • Link analysis trace information
    The link analysis messages now display trace information when relevant. For checks looking for conflicting symbol names, all conflicting declarations are now listed in the trace information instead of each pair of conflicts being described in a separate message. This might lead to fewer reported messages for the same number of found issues.

IAR Build Tools for Linux

A new product, IAR Build Tools for Renesas RX is available. It contains the IAR C/C++ Compiler, IAR Assembler, Linker and library tools, C-STAT, IARBuild, and runtime libraries. Get product info

Renesas Smart Configurator update

The Renesas Smart Configurator (included) has been updated to V2.7.0.

Read complete release notes

Version 4.14

  • RX72N and RX66N supported
    The RX72N and RX66N groups of microcontrollers are now supported
  • Renesas Smart Configurator update
    The Renesas Smart Configurator (included) has been updated to V2.4.0
Read full release notes

Wide support for MCU devices

Supported Renesas RX devices

IAR Embedded Workbench for Renesas RX enables you to take full advantage of the performance and power-efficient capabilities of Renesas RX MCUs.

See all supported devices

What type of license do you need?

Our tools are available in a flexible license model to suit your company needs. Together with our support and update agreements, you get the support you need in multiple time zones and multiple languages. Send a request for quote or contact sales to get started.

Read more about Licenses

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Download free trial

IAR Embedded Workbench for Renesas RX - Free trial version

The evaluation license is completely free of charge and allows you to try the software to evaluate its efficiency and ease of use. You can choose either a 14-days trial version or a size-limited version.

When you click download, you will be asked to register to get your license.

Please note the following for the 14-day time-limited version:

  • Time limit for evaluation license is 14 days
  • Not allowed to be used for product development or any kind of commercial use
  • Source code for runtime libraries is not included
  • No support for MISRA C
  • C-RUN is size-limited to 12 Kbytes of code, excluding constant data.
  • Limited technical support

Please note the following for the Kickstart, size-limited version:

  • A 64 Kbyte code size limitation.
  • Source code for runtime libraries is not included.
  • No support for MISRA C.
  • C-RUN is not available.
  • Limited technical support.
Download 933.55 MB

User guides and documentation

Hardware debugging and RTOS support

Debugging system support

  • Renesas E1 Emulator
  • Renesas E2 Emulator
  • Renesas E2 Emulator Lite
  • Renesas E20
  • Segger J-Link
  • C-SPY Debugger plugin SDK available for 3rd party debuggers

RTOS support

  • OSEK Run Time Interface ORTI
  • Express Logic
  • Micrium
  • FreeRTOS
  • CMX
  • embOS

The RTOS plugin installs a number of new windows in C-SPY, most importantly the task or thread list windows where task-specific breakpoints can be specified and task-specific steps executed. Different inspector windows display the contents of the internal data structures of the RTOS such as timers, queues, semaphores, resources and mailboxes.

Languages and standards

The IAR C/C++ compilers offer different dialects of the C and C++ programming languages, as well as different extensions specific for embedded programming (please note that not all language standards are supported for all target implementations). The compiler can be instructed to disable extensions for strict conformance to the standards. 

A wide range of industry-standard debug and image formats compatible with most popular debuggers and emulators are supported. This includes ELF/DWARF where applicable.

ISO/ANSI C/C++ Compliance

The IAR C/C++ compilers adhere to a freestanding implementation of the following C programming language standards:

  • INCITS/ISO/IEC 9899:2018, known as C18 (Latest version only).
  • The compiler supports all C++17 features. The C++ library supports C++14 with no C++17 additions.  (Latest version only).
  • ISO/IEC 14882:2015, known as C++14
  • INCITS/ISO/IEC 9899:2012, known as C11
  • ANSI X3.159-1989, known as C89

The ISO/ANSI C/C++ Compliance level varies between the different compilers. For complete information, please refer to the IAR C/C++ Compiler user documentation in your chosen product.

IEEE 754 standard

IAR Embedded Workbench supports the IEEE 754 standard for floating-point arithmetic.


MISRA C is a software development standard for the C programming language developed by MISRA, The Motor Industry Software Reliability Association. Its aims are to facilitate code safety, portability and reliability in the context of embedded systems, specifically those systems programmed in ISO C.

The first edition of the MISRA C standard, "Guidelines for the use of the C language in vehicle based software", was produced in 1998. In 2004, a second edition was produced with many substantial changes to the guidelines, including a complete renumbering of the rules. Additionally MISRA C:2012 with extended support and MISRA C++:2008 for identifying unsafe code constructs in the C++ standard have also been added to the standards.

IAR Embedded Workbench features an add-on product C-STAT so you can check compliance with rules as defined by MISRA C:2004, MISRA C++:2008 and MISRA C:2012.

Test validation

We use the following commercial test suites to test conformance of our tools to the standards:

  • Plum Hall Validation test suite for ISO/IEC C conformance
  • Perennial EC++ Validation Suite for C++ conformance
  • Dinkum C++ Proofer to test how our libraries conform to the C and C++ standard as well as test our STL implementation against the C++ standard.

In addition to the commercial suites, we use several in-house test suites for testing new features, regression testing, corrected errors, etc.

Renesas FIT support

Renesas FIT simplifies development for the RX family. The technology is supported by IAR Embedded Workbench for RX.

Renesas FIT consists of a Board Support Package (BSP), peripheral function modules, middleware modules, and interface modules and these can be used with IAR Embedded Workbench for RX.

The tool Renesas Smart Configurator, supplied with IAR Embedded Workbench for RX, supports the following three functions related to embedding Renesas drivers in your systems:

  • importing FIT modules
  • generating driver code
  • generating device configuration code

The generated modules are incorporated via the IAR Project Connection mechanism.


Benchmark results

The sophisticated optimization technology of IAR Embedded Workbench for RX generates very compact and fast code.

Code size benchmark test

For this benchmark we took real customer applications and tested for size. The benchmark compares the total size of linked code and constants between code from IAR Embedded Workbench, CC RX and GCC.

In total for the tested applications, IAR Embedded Workbench generated 27 % smaller code than CC RX and 27 % smaller code than GCC.


Tools and options for RX code size benchmark

This is a code size test on real customer applications where the size of linked code + constants has been compared. The test was performed with the following tools and options: 

CC-Rx v3.03.00
Options: ccrx -isa=rxv3 -fpu -tfu=intrinsic -lang=c -nomessage -show=source,conditionals,definitions,expansions -optimize=max -nologo

IAR EWRX v4.20
Options: iccrx -e -Ohz --double=32 --data_model=n --align_func=1 --endian l --core rxv3 --tfu=intrinsic --dlib_config=dlib_defaults.h --no_warnings

GCC for Renesas RX v8.3.0
gcc-rx-elf -nostdinc -Os -fdata-sections -ffunction-sections -g -flto -mlittle-endian-data -mcpu=rx72t -mtfu=intrinsic -misa=v3 -c


Remote monitoring and operation for generators and engines. generator_controller
Turbogenerator technology, "turbocompounding" engine_control
Car navigation system car_navig
Embedded Internet Toolkit modeit
Microwave sensor application microwave_sensor
Telecommunication signal processing gsm_efr
Spirometer firmware spirometer
Reed-Solomon encoding/decoding Reed_Solomon_decoder
Functions to descramble CSS encrypted DVD content. decrypt
Blowfish algorithm blowfish
Boolean bit operations bittest
Insert and extract bit fields bfix

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