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
Copyright © 2011 DSR Corporation
Scalability
Enhancement
Compatibility Enhancement
1
ITRON Usage (cont.)
Copyright © 2011 DSR Corporation
2
Configure the System
 .c and .h files are generated as a result of configurator functioning
RTOS
configuration file
Source files for the
task
Source files for the
interrupt handler
Configurator
Software
Components
Software Components
Other
Libraries
RTOS
Libraries
Compiling and linking
Object file
To ROM
ＭＰＵ
Copyright © 2011 DSR Corporation
3
Task States (cont.)
Copyright © 2011 DSR Corporation
4
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
Copyright © 2011 DSR Corporation
5
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
Copyright © 2011 DSR Corporation
6
Semaphore (cont.)
 Semaphore usage example
Task 1
Semaphore
Task 2
(Priority: Low)
(SID1)
(Priority: High)
Semaphore acquire req.
Semaphore acquired
Sem. resource number = 1
Sem. resource number = 0
Start
Work with shared resources
Semaphore acquire req.
Dispatch
Release semaphore
Semaphore acquired
Wait release, dispatch
Work with shared resources
Copyright © 2011 DSR Corporation
7
Eventflag (cont.)
 Eventflag usage example
Task 1
Task 2
Eventflag
(Priority: Low)
Event flag is cleared
(Priority: High)
flag=00
Starting
Wait for event 11
Dispatch
Set event flag 01
Release waiting
flag=01
Copyright © 2011 DSR Corporation
Wait release, dispatch
8
Data Queue (cont.)
 Data queue functioning example: wait for receive
Task 1
Data queue
(Priority: Low)
Task 2
(Priority: High)
Empty queue
Dispatch
Receive message
Receive wait
Send message
Release waiting
Wait release, dispatch
Copyright © 2011 DSR Corporation
9
Data Queue (cont.)
 Data queue functioning example: asynchronous send
Task 1
Data queue
(Priority: Low)
Task 2
(Priority: High)
Empty queue
Time
Send a message
Start
1 message in queue
Receive message
Empty queue
Copyright © 2011 DSR Corporation
10
Data Queue (cont.)
 Data queue functioning example: wait for send
Task 1
Data queue
(Priority: Low)
Task 2
(Priority: Low)
Queue is full
Send a message
Dispatch
Send-wait state
Data queue
Wait release, dispatch
Receive message
Put data to queue
Queue is full
Copyright © 2011 DSR Corporation
11
References

μITRON4.0 Specification


RTEMS ITRON 3.0 User’s Guide


http://citforum.ru/operating_systems/rtos/27.shtml
FAQ of ITRON Specification OS


http://ecos.sourceware.org/docs-1.3.1/ref/ecos-ref.a.html
ITRON short description


http://www.rtems.com/onlinedocs/releases/rtemsdocs-4.9.4/share/rtems/pdf/itron.pdf
eCOS μITRON API


http://www.t-engine.org/wp-content/themes/wp.vicuna/pdf/specifications/en_US/WG024-S00104.03.00_en.pdf
http://www.t-engine.org/tron-project/itron/itron-faq
TOPEERS/JSP

http://www.toppers.jp/en/index.html
Copyright © 2011 DSR Corporation
12