ITRON History ITRON1 – designed for 8 and 16 bit MCU ITRON2 – support 32 bit MCU μITRON2 –...

ITRON History

ITRON1 – designed for 8 and 16 bit MCU ITRON2 – support 32 bit MCU μITRON2 – adaptation for low-cost MCU μITRON3 – scalability enhancements

μITRON4 – compatibility enhancement

Targeted for 32 bit MPU

The first spec for ITRON Kernel

Targeted for 8-bit and 16-bit MCU

Scalability Enhancement

Compatibility Enhancement

Copyright © 2011 DSR CorporationCopyright © 2011 DSR Corporation 11

ITRON Usage (cont.)


Configure the System

RTOSconfiguration file

Source files for the task

Source files for the interrupt handler

Configurator

Compiling and linking

Software Components

Object file

ＭＰＵ

To ROM

RTOS Libraries

Software Components

OtherLibraries

.c and .h files are generated as a result of configurator functioning


Task States (cont.)


Scheduling Rules (cont.)

Scheduling example Task A of the highest priority

Task B, C, D of the middle priority

Task E of the lowest priority

Workflow Task A terminates, task B moves to RUNNING state

If task B goes to WAITING or SUSPENDEND state and then back to READY, it has the lowest precedence

If Task A is reactivated, Task B is pre-empted and return to the READY state, it has the highest precedence


Dispatch Pending State• Dispatch does not occur (dispatch pending state)

– During execution of processing units with higher precedence than that of the dispatcher

– The CPU in locked state

– Dispatch disabled state

• Task state transition into SUSPENDED or DORMANT state is hold until dispatch is turned on– Task state transition may be done using service calls from non-task context

Low priority task A is running

Dispatch pending state during interrupt handler execution

High priority task B is activated from interrupt handler

Task state changes only after dispatcher executes


Semaphore (cont.)

Semaphore usage example

Semaphore acquire req.

Semaphore acquired

Semaphore(SID1)

Work with shared resources

Release semaphore

Semaphore acquire req.

Work with shared resources

Sem. resource number = 0

Sem. resource number = 1

Start

Semaphore acquired

Dispatch

Wait release, dispatch

Task 1 (Priority: Low)

Task 2(Priority: High)


Eventflag (cont.)

Eventflag usage example

Event flag is cleared

Set event flag 01 Release waiting

flag=01

flag=00

Wait for event 11

Starting

Dispatch


Task 1(Priority: Low)

EventflagTask 2

(Priority: High)


Data Queue (cont.)

Data queue functioning example: wait for receive

Empty queue

Data queue

Receive message

Release waitingSend message



Task 2(Priority: High)

Dispatch

Receive wait


Data Queue (cont.)

Data queue functioning example: asynchronous send

1 message in queueStart


Data queueTask 2

(Priority: High)

Time Send a message

Empty queue

Receive message

Empty queue


Data Queue (cont.)

Data queue functioning example: wait for send

Queue is full

Queue is full

Send a message

Receive messageData queue

Put data to queue

Send-wait state

Dispatch


Task 1(Priority: Low) Data queue



References μITRON4.0 Specification

http://www.t-engine.org/wp-content/themes/wp.vicuna/pdf/specifications/en_US/WG024-S001-04.03.00_en.pdf

RTEMS ITRON 3.0 User’s Guide

http://www.rtems.com/onlinedocs/releases/rtemsdocs-4.9.4/share/rtems/pdf/itron.pdf

eCOS μITRON API

http://ecos.sourceware.org/docs-1.3.1/ref/ecos-ref.a.html

ITRON short description

http://citforum.ru/operating_systems/rtos/27.shtml

FAQ of ITRON Specification OS

http://www.t-engine.org/tron-project/itron/itron-faq

TOPEERS/JSP

http://www.toppers.jp/en/index.html




ITRON History ITRON1 – designed for 8 and 16 bit MCU ITRON2 – support 32 bit MCU μITRON2 –...

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