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.


  • Conformance with the µITRON4.0 Specification
    The design conforms with the µITRON4.0 Specification, which prescribes a representative OS architecture for embedded control.
  • High performance: Fast interrupt response
    For application requiring fast interrupt response time, M3T-MR30/4 is designed to realize fast response to an interrupt which does not issue a system call.
  • 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 cfg30 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]
  • C and Assembly user interfaces
    When using the supported compiler package, the following features are available.
    • Kernel direct call: The kernel can be called without the C interface library. This function reduces code size and speeds up execution time.
    • Simplified coding tasks and handlers: Start functions of a task or handler can be specified in the C source file, allowing start and termination processing optimization.
    • Context selection function: A register to be saved at task-switching can be specified. This function eliminates unnecessary register saving, reduces stack usage, and offers improved execution speed.
  • Interlinking with the High-performance Embedded Workshop IDE
    OS-embedded applications can be developed using common operations of the Renesas MCU toolchain.
  • Supported compiler: M16C/60, 50, 30, 20, 10, Tiny series, C/C++ Compiler Package for M16C Series and R8C Family [M3T-NC30WA], Assembler: AS30
  • Learn More

Release Information

Latest Ver.: V.4.01.00
Released: Sep 16, 2011
Details of upgrade (See Tool News)
Operating Environment

Agreement Details

Notes of Target Devices: The automatic routine setup function for initializing timer does not support the following MCUs.

  • R8C Family
  • M16C/60 Series : M16C/63 Group, M16C/64 Group, M16C/64A Group, M16C/65 Group

Target Devices


Additional Details


The M3T-MR30/4 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 M3T-MR30/4 kernel and starts user-defined alarm handler and cyclic handler.
  • System State Management
    Reports information such as version number of M3T-MR308/4 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.
    • Mail box
      Tasks are synchronized by sending or receiving a message.
    • Data queue
      Tasks are synchronized by communicating 2-byte data.
  • Memory pool management
    Dynamically allocates/frees memory area used by tasks. Enables efficient use of memory.
  • 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 M16C/60, M16C/50, M16C/30, M16C/20, M16C/10, M16C/Tiny Series, 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 mail boxes 255
Max. number of data queue 255
Data queue size 16 bits (32 bits is supported as extended function.)
Max. number of fixed-length memorypools 255
Max. number of variable-length memorypools 255
Max. number of cyclic handler 255
Max. number of alarm handler 255
Number of service call 133
Kernel language Assembly language, C language
(Time takes for a target task to be executed after the wup_tas is issued.)
30 microseconds (M16C/60, 10MHz, embedded memory)
Kernel code size Approximately 3K to 21K bytes
Kernel RAM usage per task Data: 11 bytes
Stack: 8 bytes

Components of Evaluation License Package

Kernel library mr30.lib
Kernel library source files Not included.
(* Included with Mass-production License  Package)
Configurator cfg30
Utilities mkmrtbl, echo30
Default configuration file default.cfg
C interface library c30mr.lib
C interface library source file and makefile 25 files
C language include file itron.h, kernel.h, kernel_api.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
Database file for generating makefile makefile.dos
Table database file mrtable.tpl
Service call file for issuing service call isssys.mrc
Include database file mr30.inc
M3T-MR30/4 version file version
Sample program demo.c, smp.cfg

Processing Flow