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S3C8248/C8245/P8245/C8247/C8249/P8249
INTERRUPT STRUCTURE
5-1
5
INTERRUPT STRUCTURE
OVERVIEW
The S3C8-series interrupt structure has three basic components: levels, vectors, and sources. The SAM8 CPU
recognizes up to eight interrupt levels and supports up to 128 interrupt vectors. When a specific interrupt level
has more than one vector address, the vector priorities are established in hardware. A vector address can be
assigned to one or more sources.
Levels
Interrupt levels are the main unit for interrupt priority assignment and recognition. All peripherals and I/O blocks
can issue interrupt requests. In other words, peripheral and I/O operations are interrupt-driven. There are eight
possible interrupt levels: IRQ0–IRQ7, also called level 0–level 7. Each interrupt level directly corresponds to an
interrupt request number (IRQn). The total number of interrupt levels used in the interrupt structure varies from
device to device. The S3C8248/C8245/C8247/C8249 interrupt structure recognizes eight interrupt levels.
The interrupt level numbers 0 through 7 do not necessarily indicate the relative priority of the levels. They are just
identifiers for the interrupt levels that are recognized by the CPU. The relative priority of different interrupt levels
is determined by settings in the interrupt priority register, IPR. Interrupt group and subgroup logic controlled by
IPR settings lets you define more complex priority relationships between different levels.
Vectors
Each interrupt level can have one or more interrupt vectors, or it may have no vector address assigned at all.
The maximum number of vectors that can be supported for a given level is 128 (The actual number of vectors
used for S3C8-series devices is always much smaller). If an interrupt level has more than one vector address, the
vector priorities are set in hardware. S3C8248/C8245/C8247/C8249 uses sixteen vectors.
Sources
A source is any peripheral that generates an interrupt. A source can be an external pin or a counter overflow.
Each vector can have several interrupt sources. In the S3C8248/C8245/C8247/C8249 interrupt structure, there
are sixteen possible interrupt sources.
When a service routine starts, the respective pending bit should be either cleared automatically by hardware or
cleared "manually" by program software. The characteristics of the source's pending mechanism determine which
method would be used to clear its respective pending bit.
Содержание S3C8248
Страница 31: ...ADDRESS SPACES S3C8248 C8245 P8245 C8247 C8249 P8249 2 20 NOTES ...
Страница 107: ...INTERRUPT STRUCTURE S3C8248 C8245 P8245 C8247 C8249 P8249 5 18 NOTES ...
Страница 195: ...INSTRUCTION SET S3C8248 C8245 P8245 C8247 C8249 P8249 6 88 NOTES ...
Страница 221: ...I O PORTS S3C8248 C8245 P8245 C8247 C8249 P8249 9 16 NOTES ...
Страница 245: ...16 BIT TIMER 0 1 S3C8248 C8245 P8245 C8247 C8249 P8249 12 10 NOTES ...
Страница 249: ...WATCH TIMER S3C8248 C8245 P8245 C8247 C8249 P8249 13 4 NOTES ...
Страница 267: ...A D CONVERTER S3C8248 C8245 P8245 C8247 C8249 P8249 15 6 NOTES ...
Страница 299: ...S3P8245 P8249 OTP S3C8248 C8245 P8245 C8247 C8249 P8249 21 8 NOTES ...
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Страница 315: ...BOOK SPINE TEXT SAMSUNG Logo S3C8248 C8245 P8245 C8247 C8249 P8249 Microcontrollers User s Manual Rev 3 March 2002 ...