MR8C/4 Real-time OS for R8C Family (Discontinued product)
Support for this product is limited to customers who have already adopted these products. If adopting new products, please consider the successor, M3T-MR30/4.
Overview
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.
- The TRON Association holds the copyright on the μITRON Specification.
- TRON, ITRON, and μITRON do not refer to any specific product or products.
Release Information
Features
- Conforms to industry standard μITRON 4.0 specifications
The μITRON arranges and standardizes the ITRON specifications for embedded systems. MR8C/4 conforms to the μITRON 4.0 specifications, and provides service calls suitable for R8C Family MCU functions. - Compact size for ROM
The MR8C/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. - Integrated development environment High-performance Embedded Workshop supported
From the Renesas integrated development environment "High-performance Embedded Workshop" (included in M3T-NC30WA) 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 cfg8c 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.

Screen Image : Configurator
Functions
The MR8C/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 MR8C/4 kernel and starts user-defined alarm handler and cyclic handler. - System State Management
Reports information such as version number of MR8C/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. - Data queue
Tasks are synchronized by communicating 2-byte data.
- Event flag
- 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.
Specifications
Target MCU | R8C Family |
---|---|
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 data queue | 255 |
Data queue size | 16 bits |
Max. number of cyclic handler | 255 |
Max. number of alarm handler | 255 |
Number of service call | 43 |
Kernel language | Assembly language, C language |
Performance (Time takes for a target task to be executed after the wup_tas is issued.) |
19 microseconds (20MHz) |
Kernel code size | Approximately 1.5K to 6.5K bytes |
Kernel RAM usage per task | Data: 11 bytes Stack 8 bytes |
Components of Evaluation License Package
Kernel library | mr8c.lib |
---|---|
Kernel library source files | Not included. (* Included with Mass-production License Package) |
Configurator | cfg8c |
Utilities | mr8ctbl |
Default configuration file | default.cfg |
C interface library | c8cmr.lib |
C language include file | itron.h, kernel.h, kernel_api.h, kernel_sysint.h |
Sample start-up program | [For NC30] crt0mr.a30 [For AS30] start.a30 |
Sample Section definition file | [For NC30] c_sec.inc [For AS30] asm_sec.inc |
System RAM area definition database file | sys_ram.inc |
Table database file | mrtable.tpl |
Service call file for issuing service call | isssys.mrc |
Include database file | mr8c.inc |
MR8C/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.)
- MR8C/4 kernel libraries (mr8c.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 |
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R8C Family |
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Information supporting development tools
Title | Description |
---|---|
My Renesas | Create a My Renesas account to use our tool download services, receive e-newsletter/update notifications, and take advantage of our other services. |
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. |