DISCONTINUED SOFTWARE NOTICE - This software / tool has been discontinued.
Software support will continue in most cases. Please contact Renesas support with any questions.

This product is a real-time operating system (real-time OS) that is an implementation of the μITRON4.0 specification. μITRON is the predominant real-time OS for embedded systems in Japan. Its low resource requirements, outstanding real-time performance, and broad range of service calls make it very suitable for embedded systems requiring true real-time and multi-tasking capabilities.

In addition, its high degree of compatibility with the compiler package from Renesas Electronics and the configurator which automatically generates startup files will help you greatly reduce development times and get your products to market more quickly.

Successors:M3T-MR30/4 Real-time OS for M16C Series and R8C Family



  • Conformance with the µITRON4.0 Specification
    The design conforms with the µITRON4.0 Specification, which prescribes a representative OS architecture for embedded control.
  • ROM-based implementation
    The kernel is provided in library format. You can link only the functions you need at the time of system generation and minimize application software size.
  • Equipped with the configurator
    The configurator is equipped which makes the setup of OS construction parameters easier. Using the combination of GUI configurator and cfg8c configurator based command line lets you automatically generate start-up programs that rely on development products by just creating a simple definition file (configuration file), and so on. You can easily and reliably process parts specially suited to the product. [Learn More]
  • Interlinking with the High-performance Embedded Workshop IDE
    OS-embedded applications can be developed using common operations of the Renesas MCU toolchain.
  • Supported compiler: C/C++ Compiler Package for M16C Series and R8C Family [M3T-NC30WA]
  • Learn More

Release Information

Latest Ver.: V1.01.00
Released: Sep 16, 2011
Details of upgrade (See Tool News)
Operating Environment
Agreement Details


Title language Type Format File Size Date
User Guides & Manuals
Real-time OS RI600/4 for RX600 Series Application Note: Application Transition Guide (from M3T-MR30/4 to RI600/4) 日本語 Guide PDF 371 KB
MR8C/4 V.1.01 User's Manual (Real-time OS for R8C Family) 日本語 Manual PDF 1.07 MB
Application Notes & White Papers
R8C Family Implementing Interrupts in MR8C/4 Application Note PDF 695 KB
R8C Family Implementing System Timer in MR8C/4 Application Note PDF 126 KB
R8C Family Implementing Time Event Handlers in MR8C/4 Application Note PDF 938 KB
High-performance Embedded Workshop Application Note: Real-time OS aware debugging Application Note PDF 750 KB
Creating Workspace with MR8C/4 日本語, 简体中文 Application Note PDF 897 KB
Debugging with MR8C/4 简体中文 Application Note PDF 469 KB
General RTOS Concepts Application Note PDF 801 KB
How to Compute MR8C/4 User Stack and System Stack 简体中文 Application Note PDF 583 KB
How to Implement MR8C/4 in Embedded Applications Application Note PDF 760 KB
How to Implement Timeout Feature in MR8C4 Application Note PDF 152 KB
How to use Data Queue in place of Mailbox Application Note PDF 325 KB
- Source code for Workspace Creation Application Note on MR8C/4 OS Sample Code ZIP 879 KB
- 看门狗定时器的使用 Sample Code ZIP 283 KB
- Source code for Application note on how to debug applications running on MR8C/4 Sample Code ZIP 877 KB
- 定时器 A操作(事件计数模式、自由运行方式) Sample Code ZIP 257 KB
- 定时器A操作(事件计数模式中的二相脉冲信号处理、4倍频方式) Sample Code ZIP 264 KB
- Source code for Application Note on how to implement MR8C/4 in Embedded Applications Sample Code ZIP 952 KB
- Source code for Application Note on Implementing Timeout Feature in MR8C/4 Sample Code ZIP 176 KB
- Source code for Application Note on how to use Data Queue in place of Mailbox Sample Code ZIP 364 KB
Tool News
Notes on Using Real-Time OSes for R8C and M16C MCU Families 日本語 Tool News - Note PDF 204 KB
Real-Time OS MR8C/4 Revised to V.1.01 Release 00 日本語 Tool News - Release PDF 202 KB
Real-Time OS MR8C/4" Published" 日本語 Tool News - Release PDF 195 KB
MR8C/4 V.1.01 Release 00 Release Note (Real-time OS for R8C Family) 日本語 Release Note PDF 237 KB


M3T-MR30/4 Real-time OS for M16C Series and R8C Family


Target MCU R8C Family
Max. number of tasks 255
Number of priority levels 255
Max. number of eventflags 255
Width of an eventflag 16 bits
Max. number of semaphores 255
Type of semaphores Counter type
Max. number of data queue 255
Data queue size 16 bits
Max. number of cyclic handler 255
Max. number of alarm handler 255
Number of service call 43
Kernel language Assembly language, C language
(Time takes for a target task to be executed after the wup_tas is issued.)
19 microseconds (20MHz)
Kernel code size Approximately 1.5K to 6.5K bytes
Kernel RAM usage per task Data: 11 bytes
Stack 8 bytes

Components of Evaluation License Package

Kernel library mr8c.lib
Kernel library source files Not included.
(* Included with Mass-production License  Package)
Configurator cfg8c
Utilities mr8ctbl
Default configuration file default.cfg
C interface library c8cmr.lib
C language include file itron.h, kernel.h, kernel_api.h, kernel_sysint.h
Sample start-up program [For NC30] crt0mr.a30
[For AS30] start.a30
Sample Section definition file [For NC30] c_sec.inc
[For AS30] asm_sec.inc
System RAM area definition database file sys_ram.inc
Table database file mrtable.tpl
Service call file for issuing service call isssys.mrc
Include database file mr8c.inc
MR8C/4 version file version
Sample program demo.c, smp.cfg

Components of Mass-production License Package

(1) With source code

  • Components of Evaluation License Package
  • Mass production rights (For details, see the License Agreement.)
  • MR8C/4 kernel libraries (mr8c.lib) source files

(2) No source code

  • Components of Evaluation License Package
  • Mass production rights (For details, see the License Agreement.)

Processing Flow