University of Tokyo professor Ken Sakamura advocated the TRON project in 1984. The µITRON specification is one of the real-time operating system specifications standardized in the ITRON project established as a subproject of the TRON project.

The µITRON specification is now a de facto standard in the Japanese embedded industry.

Renesas Electronics Corp. has been participating in the TRON project since the project was established. [HI series OS] is a realtime operating system for the Renesas H8/SH microcomputers which is compliant with uITRON specifications.

Release Information

Latest Ver.: V.1.06 Release 00

Released: Nov 16, 2008

Details of upgrade (See Tool News)

Operating Environment

Agreement Details


  • Conforms to industry standard μITRON 4.0 specifications
    • HI series OS conforms to the µITRON 4.0 specifications, and is the dedicated real-time OS for Renesas H8SX and H8S microcomputers.
  • Real-time performance
    • The latest HI1000/4 realizes a fast task switching* of 7.4 microseconds.
      *Time it takes a target task to be activated after a wup_tsk is issued. (H8SX/1650@35MHz, when on-chip memory is used)
  • Superb functionality
    • Supports more than 70 service calls, such as the dynamic task generation system call. They support various applications.
  • Configurator
    • In the specifications of the HI1000/4 series of uITRON4.0, a configurator is equipped which makes the setup of OS construction parameters easier.

Screen Image : Configurator


  • Debugging Extension (option)
    • The Debugging Extension is an optional software which extends the multi-task functionality in High-performance Embedded Workshop, and can be downloaded for frees from the website.
    • The following functionalities are offered by the Debugging Extension.
      • Shows the object status of tasks and semaphores managed by OS
      • Issues the service calls for task activation and event flag setting etc.
      • Displays the service call history
      • Graphically-displayed service call history

Screen Image : Debugging Extension

  • Cooperation with 3rd parties
    • We provide various solutions to deliver great environments for debugger/application software development, distribution of middleware, customization, and hardware platforms etc. in conjunction with our partner vendors.



The HI1000/4 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.
  • Time management
    Sets system timer used by HI1000/4 kernel and starts user-defined cyclic handler.
  • System State Management
    Reports information such as version number of HI1000/4 kernel.
  • 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 4-byte data.
  • Extended Synchronization/Communication
    Carries out synchronization and communication between tasks. The following function module is available:
    • 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
    Controls the execution of a handler activated periodically.


Kernel specifications

Specifications/Functions: Compliant with μITRON 4.0 specification
  • Mutex function
  • Data queue function
Scheduling types: Priority basis type / Event-driven type
Service call number: 79
(Count xxx_yyy plus ixxx_yyy as one)
Maximum object number: 255 (Only the cycle handler and the alarm handler have 15 each)
A maximum value can be selected with the configurator
Maximum Priority number: 31, A maximum value can be selected with the configurator
(Time takes for a target task to be executed after the wup_tas is issued.) :
7.4 microseconds
(H8SX/1650, 35MHz, when on-chip memory is used in the advanced mode)

17.2 microseconds
(H8S/2655, 20MHz, when on-chip memory is used in the advanced mode )
Kernel code size : From 2.3K bytes to 27.2K bytes
Kernel RAM usage per task: Data: 20 bytes
Stack: 50 bytes



Item Description Note
Kernel souce program Kernel source program Provided only with mass- production licenses which include source code.
Kernel library Kernel library for system configuration Supports advanced mode
Standard header files
  • ITRON specification common definition files
  • Kernel specification definition files
  • Other definition files
Header files are provided both in Assembler and C languages
Configurator To setup configuration parameters  -
Various sample programs
  • CPU initialization routine assembler source
  • System idling routine source
  • Undefined interrupt detailed information acquisition process source
  • System down routine source
  • Timer driver source
Workspace for configuration HEW workspace for system configuration
Manual HI1000/4series user's manual  


Processing Flow



Target Devices

Information supporting development tools

Title Description
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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.