This product was 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 CS+, e2 studio IDE and the configurator which automatically generates startup files will help you greatly reduce development times and get your products to market more quickly.

This product is also available in the free trial version.

Note: RI600V4 is not generally promoted to U.S. and European customers.


  • Conformance with the µITRON4.0 Specification
    The design conforms with the µITRON4.0 Specification, which prescribes a representative OS architecture for embedded control.
  • The register-bank save function accelerates the saving and restoring of register values
    The register-bank save function (optional function for the RXv3 architecture) is now supported. The register-bank save function increases the speed and precision of interrupt handling. The register-bank save function is available for tasks, interrupt handlers, and fixed interrupt handlers in RI600V4.[Learn More]
  • ROM-based implementation
    Since the system is a real-time/multi-tasking OS assumed to be used embedded in the execution environment, it was designed to be compact and ready for ROM-based implementations. Also, because the system can be configured linking only the service calls used in the system by the user (rather than all the service calls provided by the RI600V4), a real-time/multi-tasking OS can be configured which is compact and optimized for the user's needs.
  • Interface with CS+ and e2 studio, the Renesas Electronics Integrated Development Environment
    The following features are available in CS+ and e 2 studio IDE:
    • Automatic settings for options required in building the OS
    • Displaying the states of OS control objects such as tasks, semaphores, etc. (Resource Information)
    • Graphical display of the history of task operations and of issuing service calls(Task Analyzer)
  • Sample Projects (CS+ edition) Provided for FIT (compared with V1.05.00)
    Sample projects (CS+ edition) for the use of Firmware Integration Technology (FIT) with the RI600V4 real-time operating systems (Real-time OS) for the RX family are supplied. Download the sample project for FIT from Documentation & Downloads.
  • Improvements in processing speed (compared with V1.05.00)
    The speed performance has been improved in case of not using the Task Analyzer. The time for switching tasks shortened by about 4%, the interrupt response times shortened by about 7%. (These data were gathered under specific conditions, and we do not guarantee a specific increase in speed).
  • Supported compiler: CC-RX(C/C++ Compiler Package for RX Family)
  • Learn More

Release Information


Latest Ver.: V1.06.01
Released: Apr 20, 2022
Details of upgrade


  1. Preparation before update
    Fixed a memory corruption bug that occurred in the kernel library for RXv3 added in V1.06.00.
    If the workaround described in the tool news below has been implemented, please undo it before updating.
    [Notes] RI600V4 Real-Time OS for the RX Family (PDF | English, 日本語)
  2. Build an existing project
    When you build a sample program V1.05.00 or earlier, the warning (below) will be output.

    O4001 (W) : system.max_regbank is not defined

    For a workaround, see the following section in the RX Family Real-Time OS RI600V4 V1.06.01 Release Notes (PDF | English, 日本語) 6.3.2. Configurator (1)Register Bank Save Function is supported

Operating Environment
Agreement Details

CS+ interface plug-ins (Real-time OS Common plug-in)

Latest Ver.: V3.03.00
Released: Jul 1, 2016

CS+ interface plug-ins (Plug-in for RI600V4)

Latest Ver.: V3.02.01
Released: Apr 20, 2022

Target Devices

Notes of Target Devices: Depending on the memory configuration of the device, it may not be applicable.


Type Title Date
Software & Tools - Evaluation Software Log in to Download ZIP 36.67 MB 日本語
Software & Tools - Evaluation Software Log in to Download EXE 7.76 MB 日本語
2 items


Design & Development

Sample Code

Additional Details

Integrated Tools

  • Compiler: CC-RX
  • Integrated development environment: CS+e2 studio


The RI600V4 kernel consists of the following modules. Each module is provided by functions (service calls) .

  • Task management functions
    Provided by the RI600V4 include a function to reference task statuses such as priorities and detailed task information, in addition to a function to manipulate task statuses such as activation and termination of tasks.
  • Task dependent synchronization functions
    Changes task status from other task, and synchronizes tasks.
  • Synchronization and communication functions
    The synchronization and communication functions of the RI600V4 consist of Semaphores, Eventflags, Data Queues, Mailboxes, Mutex, and Message buffer that are provided as means for realizing exclusive control, queuing, and communication among tasks.
    • Semaphores:
      In the RI600V4, semaphores are provided as a means (exclusive control function) for preventing contention for limited resources (hardware devices, library function, etc.) arising from the required conditions of simultaneously running tasks.
    • Eventflags:
      Provides 32-bit eventflags as a queuing function for tasks.Data Queues:
      Provides the data queues that have the data queue area in which data read/write is enabled for transferring the prescribed size(4 bytes) of data.
    • Mailboxes:
      Provides a mailbox, as a communication function between tasks, that hands over the execution result of a given processing program to another processing program.
    • Mutex
      An object to perform exclusive control, and providing support for the feature to avoid priority inversion problems.
    • Message buffer
      An object to communicate an arbitrary-length message by copying.
  • Fixed-sized memory pool
    A function to dynamically allocate/free memory of preassign fixed size.
  • Variable-sized memory pool
    A function to dynamically allocate/free memory of arbitrary size.
  • Time management functions
    Provides methods to implement time-related processing (Timer Operations: Delayed task wakeup, Timeout, Cyclic handlers, and Alarm handlers) by using base clock timer interrupts that occur at constant intervals, as well as a function to manipulate and reference the system time. When using the time management function, it is necessary to specify RI600V4 Timer template file (PDF | English, 日本語) in the system configuration file.
  • System state management
    Provides functions for referencing the system status such as the context type and CPU lock status, as well as functions for manipulating the system status such as ready queue rotation, scheduler activation, or the like.
  • Interrupt processing
    Provides functions about interrupt handler that is called when an interrupt is occurred.
  • System configuration management
    Reports information such as version number of RI600V4 kernel.
  • Object reset function
    Initializes the Data queue, Mail box, Message buffer, Fixed-sized memory pool, Variable-sized memory pool. This function is unique to the RI600V4 and is not defined in the µITRON4.0 specifications.

Kernel specifications

Target CPU RX Family
Maximum number of tasks 255
Number of priority levels 255
Number of Service calls 143
Performance (Time takes for a target task to be executed after the wup_tsk is issued.) 2.5 microseconds (RX610, 100MHz)
Kernel code size From 6.2K bytes to 25.5K bytes
Kernel RAM usage per task data : 16 bytes
stack : 44 bytes


Provided items Explanation Note
Kernel source program Source files for the kernel Provided only with mass- production licenses which include source code.
Kernel library Kernel library for system building
Standard header files
  • ITRON specification common definition files
  • Kernel specification definition files
  • Other definition files
Header files are provided in C language.
GUI Configurator The input the construction parameters on the GUI screen allows the output of the cfg file for cfg600.
Command line configurator Outputs all types of definition files from the cfg file that describes the structure parameters in text.
Sample program A simple program using ITRON.
CS+ interface plug-ins
  • Real-time OS Common plug-in
  • Plug-in for RI600V4
  • Function for easy kernel embedding
  • Function for referencing the OS state during debug
Manual User's manual

Processing Flow


About Trial

We provide a trial software of the RI600V4 so that you can try out the functions and performance of RI600V4 before purchasing it. No support, including responses to inquiries through contact points, is provided for the trial software. Please accept this before using the trial software. In addition, please read through the Software User License Agreement ITRON (PDF | English, 日本語) and following notes before downloading.

Before Downloading

Cautionary Notes
  1. Difference with the Product Version
    Although the performance and functionality are the same as the product version, the trial software has the restrictions described below.
    • The RI600V4 real-time OS is forcibly shut down after running for an hour.
    • When the OS is shut down, the program jumps to the system down routine "_RI_sys_dwn__".
    • At this time, -64(0xffffffc0) is passed to the first argument, "type", of "_RI_sys_dwn__".
  2. Using the OS for Finished Products
    If you intend to embed the RI600V4 real-time OS in a finished product, use the product version. We do not offer any technical support services in case of troubles by using trial software.
  3. Prohibition of Redistribution
    Redistribution of the software tool to third parties is strictly prohibited.
Operating Environment

The operating environment is same as the product version. Refer to Operating Environments of Products.


Refer to RI600V4 Real-time OS for RX Family (supported by CS+ and e² studio) Trial Software Further note Rev.1.03 (PDF | English, 日本語)


We provide the CS+ and e2 studio version of the RI600V4 Trial software.

Note on Running the Product on e2 studio

If two or more e2 studio applications have been installed on the host PC, execute the following file before you start e2 studio application you want to use.

File to be executed:
<e2 studio install folder>¥eclipse¥plugins¥com.renesas.renesasos.plugins_<version>¥CSPlus¥Plugins¥OsRegister.exe

cd C:¥Renesas¥e2studio¥eclipse¥plugins¥com.renesas.renesasos.plugins_1.0.0.201408071907¥CSPlus¥Plugins¥OsRegister.exe