RI600PX Real-time OS for RX Family

infoAdditional Details

Integrated Tools

Compiler :CC-RX
Integrated development environment: CS+

Memory Protection

• High-reliability system
  To reduce a possibility of being unable to detect program glitches when debugging the program and causing a trouble in the market after the system has been shipped from the factory, this OS assures the system of high reliability.If memory data destruction occurs especially in a memory area in which the OS, etc. are stored, the system may produce a dangerous condition by, for example, operating erratically. However, since this OS is free of memory data corruptions, the system can continue operating normally, and is therefore assured of high system reliability
• Debug assistance
  In systems without memory protection, a corruption of memory content by an illegal pointer behavior, etc. generally is not noticed until it actually comes to the surface as a trouble symptom. The cause of a bug can only be identified by analyzing emulator's trace data, which requires a large amount of time. The RI600PX can detect a bug when an illegal memory access is committed, enabling the debugging efficiency to be greatly increased.

The memory protection which supports RI600PX is described below.

• Detection of illegal access by tasks.
  Tasks belong to either of domain. Furthermore, a part of address space is allocated as some memory object. A domain can be set access permissions (read, write and execute) for each memory object. The Access Exception Handler will be called if a task accesses the area that has not been permitted. In addition, handlers can access all address space.
• Protection of stack for task.
  Task cannot access the stack for another task. The Access Exception Handler will be called if a task accesses a stack for another task.
• Detection of illegal access by the kernel.
  Because of the kernel as well as a handler can access to all address space. Therefore, if an invalid pointer parameter is specified to a service call, the kernel commands itself an illegal access. To avoid such a consequence, the kernel inspects whether the task that invoked a service call can access to the space referred to by the pointer area. When it detects an illegal access, the service call returns an error.

Functions

The RI600PX 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 management function
  Makes a return from the interrupt handler.
• Time management
  Sets system timer used by RI600PX kernel and starts user-defined alarm handler and cyclic handler. When using the time management function, it is necessary to specify RI600PX Timer template file (PDF | English, 日本語) in the system configuration file.
• System configuration management
  Reports information such as version number of RI600PX kernel.
• Synchronization/communication
  Carries out synchronization and communication between tasks. The following function modules are available:
  1. Event flag
     Tasks are synchronized by the status of flags managed by the kernel.
  2. Semaphore
     Tasks are synchronized by the semaphore counter value managed by the kernel.
  3. Mail box
     Tasks are synchronized by sending or receiving a message.
  4. Data queue

Tasks are synchronized by communicating 4-byte data.

• Extended Synchronization/Communication
  Carries out synchronization and communication between tasks. The following function modules are available:
  1. Message buffer
     Makes use of variable-length data communication to synchronize tasks.
  2. 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.
• Task exception handling function
  Controls execution of task exceptions by, for example, defining or activating a task exception.
• Cyclic handler function 
  Controls the execution of a handler activated periodically.
• Alarm handler function
  Controls the execution of a handler activated at the specified relative-time.
• Memory protection function
  The following functions are available:
  1. Detection of illegal access by tasks
  2. Protection of stack for task.
  3. Detection of illegal access by the kernel

Specifications

Components

Processing Flow

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