µITRON4.0 Specification Ver. 4.00.00 ITRON Committee, TRON ASSOCIATION Supervised by Ken Sakamura Edited by Hiroaki Takada Copyright (C) 1999, 2002 by TRON ASSOCIATION, JAPAN µITRON4.0 Specification (Ver. 4.00.00) The copyright of this specification document belongs to the ITRON Committee of the TRON Association. The ITRON Committee of the TRON Association grants the permission to copy the whole or a part of this specification document and to redistribute it intact without charge or with a distribution fee. However, when a part of this specification document is redistributed, it must clearly state (1) that it is a part of the µITRON4.0 Specification document, (2) which part it was taken, and (3) the method to obtain the whole specifi- cation document. See Section 6.1 for more information on the conditions for using this specification and this specification document. Any questions regarding this specification and this specification document should be directed to the following: ITRON Committee, TRON Association Katsuta Building 5F 3-39, Mita 1-chome, Minato-ku, Tokyo 108-0073, JAPAN TEL: +81-3-3454-3191 FAX: +81-3-3454-3224 § TRON is the abbreviation of “The Real-time Operating system Nucleus.” § ITRON is the abbreviation of “Industrial TRON.” § µITRON is the abbreviation of “Micro Industrial TRON.” § BTRON is the abbreviation of “Business TRON.” § CTRON is the abbreviation of “Central and Communication TRON.” § TRON, ITRON, µITRON, BTRON, and CTRON do not refer to any specific product or products. µITRON4.0 Specification Ver. 4.00.00 A Word from the Project Leader Fifteen years have passed since the ITRON Sub-Project started as a part of the TRON Project: a real-time operating system specification for embedded equipment control. During this time, there has been a high degree of technological innovation on micro- processors, and the range of applications the ITRON Specifications cover has broad- ened considerably. The range of applications includes industrial usage such as control of robots and manufacturing equipment in factories, and consumer usage such as office automation (OA) and home appliances. The application range has even extended to new areas such as new information and communication tools and advanced digital con- sumer appliances. There is no doubt that the technological advantages of the ITRON Specifications such as real-time response, compactness to maximize usage of system resources, and flexible adaptability in specification has greatly contributed to the steady expansion of the ITRON Specifications adaptable applications. The open architecture policy of the TRON Project has also contributed to achieve a high degree of actual use of the ITRON Specifications. The µITRON4.0 Specification, which is based on the µITRON3.0 Specification, has been developed to reorganize concepts and terms, to improve compatibility and con- formance level, to increase productivity in software development, to allow reuse of application software, and to achieve more portability. The increasing cases where communication and GUI focusing on modern network applications, internet and intranet equipments, and debugging related middleware are used on the ITRON-Specification operating system serves as the background of the µITRON4.0 Specification. This trend created a demand for more rigorous compatibil - ity and higher conformance level. The ITRON Specifications are designed on a con- cept called loose standardization and level for allowing applicability to low-end CPUs with relatively scarce resources. However, strict standardization is required for soft- ware portability purposes. The specification satisfying these two contradictory demands is the µITRON4.0 Specification. The µITRON4.0 Specification maintains the loose standardization, but develops the level concept to introduce a new property called the Standard Profile. The Standard Profile supports strict standardization to facilitate software portability. Profiles other than the Standard Profile is allowed to increase compatibility in each application field. The terms and concepts in the specification have been reorganized, defined, and explained in more details, reducing as much implementation-dependent portion as pos- sible in an effort to achieve completeness of the specification. The µITRON4.0 Specification reflects the rich experience on the ITRON Specifications and meets the actual users’ demands for new applications. Introduction and effective utilization of the µITRON4.0 Specification in many fields including newly created fields and applications is expected. i µITRON4.0 Specification Ver. 4.00.00 June, 1999 Ken Sakamura Project Leader, TRON Project ii µITRON4.0 Specification Ver. 4.00.00 Preface Fifteen years have elapsed since the ITRON Project started in 1984. By the efforts of those involved, the µITRON Specifications have developed into de-facto standards for the real-time kernel for embedded systems. Based on this achievement, sometime around 1996 the ITRON Project started working towards a second phase of standard- ization to expand the specification from real-time kernel to related specifications such as software components. The µITRON4.0 Specification is the result of two years of intensive effort by both the Kernel Specification WG of the Hard Real-Time Support Study Group (from April 1997 to March 1998) and its successor, the Kernel Specification WG of the µITRON4.0 Specification Study Group (from April 1998 to June 1999). The specifica- tion study held by both WGs was proceeded with monthly meetings and discussions through email. Eventually, more than 1,000 emails regarding the discussion of the specification were exchanged. Other standardization activities in the ITRON Project, especially those done by the RTOS Automotive Application Technical Committee and the Device Driver Design Guideline WG of the µITRON4.0 Specification Study Group, produced an important part of the µITRON4.0 Specification. During the second phase of the standardization, a new approach was adopted by the ITRON Project. The ITRON Project opened the discussion of the µITRON4.0 Specifi- cation. In other words, anyone could participate in the discussion regardless of qualifi- cation. This approach was a major factor in enabling many engineers to participate in the project. Prior to this, most of the engineers did not formerly participate in the dis- cussion. The participation of application engineers as well as the participation of ker- nel engineers was very significant in organizing the specification. Another new attempt of the µITRON4.0 Specification is defining the Standard Profile in order to insure the portability of the software. Under conventional loose standard- ization policy, there is no enforced implementation agreement among members. Com- promises are adopted, and it is up to the implementors to choose specific implementation options. However, when defining the Standard Profile specification, standardizing each and every feature of the µITRON Specifications was necessary and this caused many disagreements among the members. Most disagreements were based on the difference between application requirements rather than on the difference between company interests. Nevertheless, members shared a common vision to create a better specification. Through the process outlined above, the µITRON4.0 Specification was completed reflecting variety of ideas from a variety of point of views. I am personally proud of the level of accomplishment of the µITRON4.0 Specification. I believe that this level of accomplishment could not have been achieved by a single man or company. To the readers of the µITRON4.0 Specification, I would like to remark that in the inter- iii µITRON4.0 Specification Ver. 4.00.00 ests of adhering to strictness in the specification, some readability was sacrificed. The previous µITRON Specifications included tutorial-like contents for engineers who are unfamiliar with a real-time operating system. On the other hand, the µITRON4.0 Specification is written seeking strictness rather than easiness in reading in order to secure software portability. Hence, a criticism on a lesser understandability than the previous specifications is considered to be unavoidable. Therefore we would like to work on some complementary documents such as a reference or a guide book for this specification. However, the editor’s responsibility still spans to statements which are unnecessarily difficult to understand. As a roadmap for the ITRON Specifications, the µITRON4.0 Specification Study Group is working on the standardization of the debugging interface and creating guide- lines for device driver designs. The creation of a certification system for the µITRON4.0 Standard Profile is also under consideration in the near future. We are sure that these activities will increase the acceptance of the ITRON Specifications as de-facto real-time operating system standards. Finally, I would like to express my gratitude to those who contributed to the standard- ization of the µITRON4.0 Specification. This includes those who participated in the Kernel Specification WG of the µITRON4.0 Specification Study Group, those involved in the ITRON Project, and those who directly or indirectly supported the process to develop the µITRON4.0 Specification. I would also appreciate your continuous sup- port for the standardization activities of the ITRON Project. June 1999 Hiroaki Takada Secretary of the the µITRON4.0 Spefication Study Group Department of Information and Computer Sciences, Toyohashi University of Technology