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 will help you greatly reduce development time and get to market faster.

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

Release Information

Latest Ver.: V.1.01 Release 00

Released: May 16, 2009

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. M3T-MR100/4 conforms to the μITRON 4.0 specifications, and provides service calls suitable for R32C/100 Series MCU functions.

  • Compact size for ROM
    The M3T-MR100/4 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.

  • Fast interrupt response
    For application requiring fast interrupt response time, M3T-MR100/4 is designed to realize fast response to an interrupt which does not issue a system call.

  • C and Assembly user interfaces
    Using the C Compiler Package for R32C Series provides the following functions :
    • Kernel direct call
      The M3T-MR100/4 kernel can be called without the C interface library. This function reduces code size and speeds up execution time.
      *Some service calls uses C language interface
    • 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.

  • Renesas IDE, High-performance Embedded Workshop, supported
    From the Renesas integrated development environment "High-performance Embedded Workshop" (included in the C compiler package for R32C Series) 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 cfg100 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.


The M3T-MR100/4 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-MR100/4 kernel and starts user-defined alarm handler and cyclic handler.
  • System State Management
    Reports information such as version number of M3T-MR100/4 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 recieving a message.
    • Data queue
      Tasks are synchronized by communicating 4-byte data.
  • Extended Synchronization/Communication
    Carries out synchronization and communication between tasks. The following function modules are available:
    • Message buffer
      Makes use of variable-length data communication to synchronize tasks.
    • Mutex
      Makes use of priority ceiling protocol for avoiding priority inversion to synchronize tasks.
  • 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 R32C/100 Series
Max. number of tasks 255
Number of priority levels 255
Max. number of eventflags 255
Width of an eventflag 32 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 32 bits (16 bits is supported as extended function.)
Max. number of message buffer 255
Max. number of mutex 255
Max. number of priority ceiling 255
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 149
Kernel language Assembly language, C language
(Time takes for a target task to be executed after the wup_tas is issued.)
9 microseconds (R32C/111, 48MHz)
Kernel code size Approximately 3K to 21K bytes
Kernel RAM usage per task Data: 17 bytes
Stack: 8 bytes


Components of Evaluation License Package

Kernel library mr100.lib
Kernel library source files Not included. (* Included with Mass-production License  Package)
Configurator cfg100
Utilities mr100tbl, mrecho
Default configuration file default.cfg
C interface library c100mr.lib
C interface library source file and makefile 21 files
C language include file itron.h, kernel.h, kernel_api.h
Sample start-up program [For C language] crt0mr.a30
[For assembly language] start.a30
Sample Section definition file [For C language] c_sec.inc
[For assembly language] asm_sec.inc
System RAM area definition database file sys_ram.inc
Table database file mrtable.tpl
Include database file mr100.inc
M3T-MR100/4 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.)
  • M3T-MR100/4 kernel libraries (mr100.lib) source files

(2) No source code

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

Processing Flow

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