C Compiler Package for the RL78 and 78K Families


C Compiler for RL78 and 78K Families is intended for the development of ROM-based systems for embedded applications. In addition to powerful optimization functions that help boost code efficiency and speed up program execution, this package provides extension functionality to support a broad range of embedded devices.


For RL78 Family Users; New compiler package "C Compiler Package for RL78 Family (CC-RL)" also available. Assistance in Porting Files to the CC-RL from the CA78K0R and CA78K0, please refer to here.

For 78K Family Users; Please use this product (CA78K0R, CA78K0).

Release Information

Product Name Version / Release Date Note
C Compiler and IDE for RL78/78K Family Ver.: CS+ V8.04.00
(CS+ for CA,CX V4.04.00)
Released: Jul 20, 2020
Compiler: CA78K0R (for RL78 and 78K0R)
Latest Ver.: V1.72
Released: Mar 7, 2016

Compiler: CA78K0 (for 78K0)
Latest Ver.: V1.30
Released: Nov 1, 2012

Note: Since the CS+ which is included with a compiler product might not be the latest version, you may need to upgrade before using it. Latest version of the CS+ >>


  • Supports C89 and C99 (subset of functions (For example, // comments)).
Superior optimization
  • Optimization for reducing the size or speed of executable code is available.
  • A multitude of optimization functions are easily accessible via the GUI.
Interoperation with RL78, 78K0R and 78K0 architectures
  • Interrupt handling can be accomplished by writing code in C.
  • A variety of interrupt functions are provided.
Development to match the usage application
  • Supports CS+.
  • Also supports execution from the command line.

Product Lineup

Product Name IDE Available
C Compiler and IDE for RL78/78K Family (Note1) CS+ (Note2)

 Available | — Not Available

When ordering, please contact your local Renesas Electronics marketing office or distributor.


  1. This product is different from the C compiler package for RL78 family (CC-RL).
  2. CS+ is not promoted in America and Europe. Please contact your regional marketing/sales team for information.

Information supporting development tools

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e-learning Information for studying and learning about microcontrollers and microprocessors.
FAQ Frequently asked questions and useful hints for development.
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Tool News Tool release information and other important information.
Operating Environment Information on system requirements and operating environment for the latest version of tools.
Info on Discontinued Products A list of Renesas software and tools that have been discontinued and are no longer being offered for new projects.