
Interrupt Control Unit
7-26
7.3.12
Poll Register
(POLL, Offset 24h)
(Master Mode)
When the Poll register is read, the current interrupt is acknowledged and the next interrupt
takes its place in the Poll register.
The Poll Status register mirrors the current state of the Poll register, but the Poll Status
register can be read without affecting the current interrupt request. This is a read-only
register.
Figure 7-15
Poll Register
Bit 15: Interrupt Request (IREQ)—Set to 1 if an interrupt is pending. When this bit is set
to 1, the S4–S0 field contains valid data.
Bits 14–5: Reserved—Set to 0.
Bits 4–0: Poll Status (S4–S0)—Indicates the interrupt type of the highest priority pending
interrupt (see Table 7-1). Reading the Poll register acknowledges the highest pending
interrupt and allows the next interrupt to advance into the register.
Although the IS bit is set, the interrupt service routine does not begin execution
automatically. The application software must execute the appropriate ISR.
15
7
0
S4–S0
IREQ
Reserved
Содержание Am186 ES
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Страница 12: ...Table of Contents xii...
Страница 22: ...Features and Performance 1 8...
Страница 60: ...System Overview 3 28...
Страница 84: ...Chip Select Unit 5 14...
Страница 132: ...Timer Control Unit 8 8...
Страница 166: ...Programmable I O Pins 11 6...
Страница 184: ...Register Summary A 18...