Support for this product is limited to customers who have already adopted these products. If adopting new products, please consider the successor, M3T-MR30/4.


This product is a real-time operating system (RTOS) conforming to the μITRON 4.0-specification, the predominant RTOS for embedded systems in Japan. Its compact resources, outstanding real-time features, and many service calls are suited for an embedded system with real-time ability and multi-tasking functions. In addition, its affinity for the Renesas C compiler package and the configurator which automatically generates startup files or makefile will help you greatly reduce development time and get to market faster.

  • The TRON Association holds the copyright on the μITRON Specification.
  • TRON, ITRON, and μITRON do not refer to any specific product or products.

Release Information

Latest Ver.: V1.01.00

Released: Sep 16, 2011

Details of upgrade (See Tool News)

Operating Environment

Agreement Details


  • Conforms to industry standard μITRON 4.0 specifications
    The μITRON arranges and standardizes the ITRON specifications for embedded systems. MR8C/4 conforms to the μITRON 4.0 specifications, and provides service calls suitable for R8C Family MCU functions.
  • Compact size for ROM
    The MR8C/4 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.
  • Integrated development environment High-performance Embedded Workshop supported
    From the Renesas integrated development environment "High-performance Embedded Workshop" (included in M3T-NC30WA) screen, OS-embedded applications can be developed using common operations of the Renesas MCU toolchain.
  • Easy configuration on GUI
    Using the combination of GUI configurator and cfg8c configurator based command line lets you automatically generate makefiles or start-up programs that rely on development products by just creating a simple definition file (configuration file). This enables you to install the necessary libraries without omission so you can easily and reliably process parts specially suited to the product.

Screen Image : Configurator



The MR8C/4 kernel consists of the following modules. Each module is provided by functions (service calls) .

  • Scheduler
    Manages execution sequence of multiple tasks based on their priority levels.
  • Task management
    Manages task status such as RUNNING, READY, WAITING or SUSPENDED.
  • Task-dependent synchronization
    Changes task status from other task, and synchronizes tasks.
  • Interrupt processing
    Returns from an interrupt handler, enables/disables an interrupt for each task, and so on.
  • Time management
    Sets system timer used by MR8C/4 kernel and starts user-defined alarm handler and cyclic handler.
  • System State Management
    Reports information such as version number of MR8C/4 kernel.
  • State management
    Modifies and refers system status.
  • Synchronization/communication
    Carries out synchronization and communication between tasks. The following function modules are available:
    • Event flag
      Tasks are synchronized by the status of flags managed by the kernel.
    • Semaphore
      Tasks are synchronized by the semaphore counter value managed by the kernel.
    • Data queue
      Tasks are synchronized by communicating 2-byte data.
  • Cyclic handler function
    Controlls the execution of a handler activated periodically.
  • Alarm handler function
    Controlls the execution of a handler activated at the specified relative-time.


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]
[For AS30]
System RAM area definition database file
Table database file mrtable.tpl
Service call file for issuing service call isssys.mrc
Include database file
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

Target Devices

Family Group
R8C Family

Information supporting development tools

Title Description
My Renesas Create a My Renesas account to use our tool download services,
receive e-newsletter/update notifications, and take advantage of our other services.
e-learning Information for studying and learning about microcontrollers and microprocessors.
FAQ Frequently asked questions and useful hints for development.
Forum A forum and community site to share technical information,
questions and opinions with others who use Renesas MCU's.
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.