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

Important:This product is a separate product from RI850V4 V2.00.xx.



  • Conformance with the µITRON4.0 Specification
    The design conforms with the µITRON4.0 Specification, which prescribes a representative OS architecture for embedded control.
  • Excellent portability
    To support its execution in various environments, the RI850V4 is separated into the target-dependent section for hardware-dependent processing and the parts for use in the user’s own code. Sample files of source code are provided. This enhances portability to various execution environments and facilitates customization.
  • ROM-based implementation
    Since the system is a real-time and multi-tasking OS designed on the assumption of usage in embedded execution environments, it was designed to be compact and ready for ROM-based implementation. A system can be configured with only those service calls that are actually used in the user’s application being linked (rather than all service calls provided by the RI850V4), so a real-time/multi-tasking OS which is optimally compact in terms of the user's needs can be configured.
  • Realization of memory savings
    The ability to disable preemption provided by the RI850V4 can reduce a system's memory requirements.
  • Interlinking with the CS+ Integrated Development Environment from Renesas Electronics[Learn More]
    • Automatic settings for options required in building the OS
    • Displaying the states of OS control objects such as tasks, semaphores, etc. (Resource Information)
    • Generates service calls to start up tasks from debugger, set up event flags, etc.
    • Graphical display of the history of task operations and of issuing service calls (system performance analyzer)
  • Interlinking with Green Hills Software, MULTI IDE from LLC[Learn More]
  • Supported compiler: CC-RH, GHS
  • Learn More

Release Information

Details of upgrade (See Tool News)
Operating Environment
Agreement Details


Latest Ver.: V1.01.00
Released: Oct 1, 2014

CS+ interface plug-ins (RTOS Common plug-in)

Latest Ver.: V3.00.00
Released: Oct 1, 2014

CS+ interface plug-ins (Plug-in for RI850V4 V1)

Latest Ver.: V3.00.00
Released: Oct 1, 2014

Target Devices

Synergy Download


PDF 524 KB 日本語 Manual - Development Tools
PDF 157 KB 日本語 Manual - Development Tools
PDF 265 KB 日本語 Tool News - Release
PDF 395 KB 日本語 Release Note
PDF 266 KB 日本語 Tool News - Release
PDF 203 KB 日本語 Tool News - Note
PDF 269 KB 日本語 Tool News - Note
PDF 263 KB 日本語 Tool News - Release
PDF 203 KB 日本語 Tool News - Release
PDF 240 KB 日本語 Tool News - Release
PDF 652 KB 日本語 Manual - Development Tools
PDF 202 KB 日本語 Tool News - Release
PDF 201 KB 日本語 Tool News - Note
PDF 203 KB 日本語 Tool News - Note
PDF 202 KB Tool News - Release
PDF 2.43 MB 日本語 Manual - Development Tools
PDF 3.67 MB 日本語 Manual - Development Tools
17 items

Design & Development

Sample Code

Sample Code

Title Type Date Date
ZIP 91 KB 日本語 IDE: CS+ Sample Code
1 item

Additional Details


The RI850V4 kernel consists of the following modules. Each module is provided by functions (service calls) .

  • Task management functions
    Provided by the RI850V4 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 generation, activation and termination of tasks.
  • Task dependent synchronization functions
    Changes task status from other task, and synchronizes tasks.
  • Task exception handling functions
    The task exception handling functions of the RI850V4 include a function related to the task exception handling routine that is activated when a task exception handling request is issued (function for manipulating or referencing the task exception handling routine status).
  • Synchronization and communication functions
    The synchronization and communication functions of the RI850V4 consist of Semaphores, Eventflags, Data Queues, and Mailboxes that are provided as means for realizing exclusive control, queuing, and communication among tasks.
    • Semaphores: In the RI850V4, non-negative number counting 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 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.
  • Extended synchronization and Communication functions
    Provides Mutexes as the extended synchronization and communication function for implementing exclusive control between tasks.
    • Mutexes: Provides a mutex, as a function to prevent contentions on using the resources.
  • Fixed-Sized Memory Pools
    When a dynamic memory manipulation request is issued from a processing program in the RI850V4, the fixed-sized memory pool is provided as a usable memory area.
  • Variable-Sized Memory Pools
    When a dynamic memory manipulation request is issued from a processing program in the RI850V4, the variable-sized memory pool is provided as a usable memory area.
  • Time management functions
    Provides methods to implement time-related processing (Timer Operations: Delayed task wakeup, Timeout, Cyclic handlers) by using base clock timer interrupts that occur at constant intervals, as well as a function to manipulate and reference the system time.
  • System state management functions
    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 management functions
    The RI850V4 provides as interrupt management functions related to the interrupt handlers activated when an interrupt (maskable interrupt, software interrupt, reset interrupt) is occurred.
  • Service call management functions
    Provides the function for manipulating the extended service call routine status, such as registering and calling of extended service call routines.
  • Scheduler
    The scheduling functions provided by the RI850V4 consist of functions manage/decide the order in which tasks are executed by monitoring the transition states of dynamically changing tasks, so that the CPU use right is given to the optimum task.


Target device V850
Maximum number of tasks 255
Number of priority levels 32
Service call number 132
(Time takes for a target task
to be executed after the wup_tas is issued.)
16 microseconds
(V850E/MA1, 25MHz. embedded memory)
Kernel code size From 6K bytes to 20K bytes
Kernel RAM usage per task data : 32 bytes
stack : 128 bytes


Provided items Explanation Note
Kernel source program Kernel source program 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 both in C languages
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
- RTOS Common plug-in
- Plug-in for RI850V4
Function for easy kernel embedding
Function for referencing the OS state during debug
System performance analyzer A tool that displays a transition diagram of the OS operation history and analyzes performance, such as CPU usage rate. Interfaces with CS+ and MULTI
Task debugger A tool for referencing the OS state during debug Interfaces with MULTI
Manual User's manual  

Processing Flow