SA1110 Datasheet, PDF (41/406 Pages) Intel Corporation – Intel StrongARM SA-1110 Microprocessor

ARM Implementation Options
3.2.6
3.3
Interrupt Latencies and Enable Timing
The ability to recognize an IRQ or FIQ interrupt is, in part, determined by the I and F bits of the
CPSR. To ensure that a pending interrupt is taken, an interrupt-enabling write to CPSR (msr
instruction) must be separated from an interrupt-disabling write to the CPSR by at least two
instructions.
Coprocessors
The SA-1110 has no external coprocessor bus, so it is not possible to add external coprocessors to
this device.
The SA-1110 uses the internal coprocessor designated 15 for control of the on-chip MMU, caches,
clocks, and breakpoints. Coprocessor 15 is also used for read-buffer fills and flushes. If a
coprocessor other than 15 is used, then the SA-1110 will take the undefined instruction trap. The
coprocessor load, store, and data operation instructions also take the undefined instruction trap.
Permissions are set so that access to coprocessor 15 is privileged except where protection is
programmable with respect to the read buffer operations.
SA-1110 Developer’s Manual
3-5