Hardware Reference
In-Depth Information
12.1.4
MICRO-ITRON
The ITRON (Industrial TRON - The Real-time Operating system Nucleus) project
began in 1984, in Japan. ITRON is an architecture for real-time operating systems
used to build embedded systems. The ITRON project has developed a series of de-
facto standards for real-time kernels, the previous of which was the Micro-ITRON 3.0
specification [Sak98], released in 1993. It included connection functions that allow a
single embedded system to be implemented over a network. There are approximately
50 ITRON real-time kernel products for 35 processors registered with the TRON as-
sociation, almost exclusively in Japan.
The ITRON standards primarily aim at small systems (8-16 and 32 bits). ITRON
specification kernels have been applied over a large range of embedded application
domains: audio/visual equipment (TVs, VCRs, digital cameras, STBs, audio com-
ponents), home appliances (microwave ovens, rice cookers, air-conditioners, wash-
ing machines), personal information appliances (PDAs, personal organizers, car nav-
igation systems), entertainment (game gear, electronic musical instruments), PC pe-
ripherals (printers, scanners, disk drives, CD-ROM drives), office equipment (copiers,
FAX machines, word processors), communication equipment (phone answering ma-
chines, ISDN telephones, cellular phones, PCS terminals, ATM switches, broadcasting
equipment, wireless systems, satellites), transportation (automobiles), industrial con-
trol (plant control, industrial robots) and others (elevators, vending machines, medical
equipment, data terminals).
The Micro-ITRON 4.0 specification [Tak02] combines the loose standardization that
is typical for ITRON standards with a Standard Profile that supports the strict stan-
dardization needed for portability. In defining the Standard Profile, an effort has been
made to maximize software portability while maintaining scalability. As an example,
a mechanism has been introduced for improving the portability of interrupt handlers
while keeping overhead small.
The Standard Profile assumes the following system image: high-end 16-32 bit proces-
sor, kernel size from 10 to 20 KB, whole system linked in one module, kernel object
statically generated. There is no protection mechanism. The Standard Profile supports
task priorities, semaphores, message queues, and mutual exclusion primitives with
priority inheritance and priority ceiling protocols.
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