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 multitasking debugging on the IDE will help you greatly reduce development times and get your products to market more quickly.

The H8SX family supports interrupt control mode 2.0 and CPU operating mode supports advanced mode. The H8S family supports interrupt control mode and CPU operation mode supports advanced mode and normal mode.


  • Conformance with the µITRON4.0 Specification
    The design conforms with the µITRON4.0 Specification, which prescribes a representative OS architecture for embedded control.
  • Real-time performance
    Task switching time is 7.4μsec, which is even faster than the previous product. Time it takes a target task to be activated after a wup_tsk is issued. (H8SX/1650@35MHz, when on-chip memory is used) [Learn More]
  • Superb functionality
    Supports more than 70 service calls.They support various applications.[Learn More]
  • Equipped with the configurator
    The configurator is equipped which makes the setup of OS construction parameters easier.[Learn More]
  • Supports the multi-task functionality in High-performance Embedded Workshop
    The Debugging Extension is an optional software which supports the following functions:[Learn More]:
    • Displaying the states of OS control objects such as tasks, semaphores, etc.
    • Issues the service calls for task activation and event flag setting etc.
    • Graphically-displayed service call history
  • Cooperation with 3rd parties
    We provide various solutions to deliver great environments for debugger/application software development, distribution of middleware, customization, and hardware platform etc. in conjunction with our partner vendors.
  • Target CPU: H8S Family, H8SX Family, AE-5 Series smart card MCU
  • Supported compiler: C/C++ Compiler Package for H8SX, H8S, H8 Family
  • Learn More

Release Information

Latest Ver.: V.1.06 Release 00
Released: Nov 16, 2008
Details of upgrade (See Tool News)
Operating Environment
Agreement Details

Target Devices



Additional Details


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


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


Kernel source programKernel source programProvided only with mass- production licenses which include source code.
Kernel libraryKernel library for system configurationSupports 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
ConfiguratorTo 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 configurationHEW workspace for system configuration
ManualHI1000/4series user's manual

Processing Flow


Target Devices