M3T-MR308/4 Real-time OS for M32C Series (Discontinued product)


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.

  • 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.4.00 Release 02

Released: Sep 1, 2006

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-MR308/4 conforms to the μITRON 4.0 specifications, and provides service calls suitable for M16C/80 and M32C/80 Series MCU functions.
  • Compact size for ROM
    The M3T-MR308/4 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-MR308/4 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 M3T-NC308WA and the assembler AS308 for M32C/80 and M16C/80 Series provides the following functions :
    • Kernel direct call (for NC308)
      The M3T-MR308/4 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 (for NC308)
      Start functions of a task or handler can be specified in the C source file, allowing start and termination processing optimization.
    • Context selection function (for AS308)
      A register to be saved at task-switching can be specified. This function eliminates unnecessary register saving, reduces stack usage, and offers improvemed execution speed.
  • Integrated development environment High-performance Embedded Workshop supported
    From the Renesas integrated development environment "High-performance Embedded Workshop" (included in M3T-NC308WA) 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 cfg308 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.


The M3T-MR308/4 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-MR308/4 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 recieving a message.
    • Data queue
      Tasks are synchronized by communicating 4-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 M32C/80, M16C/80 Series
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 32 bits (16 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.)
8 microseconds (M32C/83, 30MHz)
Kernel code size Approximately 3K to 21K bytes
Kernel RAM usage per task Data: 19 bytes
Stack: 12 bytes



Components of Evaluation License Package

Kernel library mr308.lib
Kernel library source files Not included.
(* Included with Mass-production License  Package)
Configurator cfg308
Utilities mr308tbl, echo308
Default configuration file default.cfg
C interface library c308mr.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 NC308] crt0mr.a30
[For AS308] start.a30
Sample Section definition file [For NC308] c_sec.inc
[For AS308] 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 mr308.inc
M3T-MR308/4 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-MR308/4 kernel libraries (mr308.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
M16C Family (R32C / M32C / M16C)
  • M16C/80 (Supported but discontinued)
  • M32C/80 (Supported but discontinued)
  • M32C/81 (Supported but discontinued)
  • M32C/82 (Supported but discontinued)
  • M32C/83 (Supported but discontinued)
  • M32C/84 (Supported but discontinued)
  • M32C/85 (Supported but discontinued)
  • M32C/86 (Supported but discontinued)
  • M32C/87 (Supported but discontinued)
  • M32C/88 (Supported but discontinued)
  • M32C/8A (Supported but discontinued)
  • M32C/8B (Supported but discontinued)

Information supporting development tools

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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
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Info on Discontinued Products A list of Renesas software and tools that have been discontinued and
are no longer being offered for new projects.