Intel
®
81341 and 81342—Inter-Processor Messaging Unit
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
822
Order Number: 315037-002US
13.2
Door Bell Registers
The Door Bell Registers provide the ability for an integrated Intel XScale
®
processor
processor to send up to 15 individual doorbells to another integrated Intel XScale
®
processor processor.
When any of a given Intel XScale
®
processor processor ‘s doorbell status (DBSTAT) bits
are set by the other Intel XScale
®
processor processor (see
Control Register — DBCR” on page 832
), an interrupt (when enabled) is signaled to
that Intel XScale
®
processor.
The IMU provides individual interrupt enables for each Door Bell bit (see
13.6.2, “Door Bell Enable Register — DBER” on page 834
) and the ability to read the
individual interrupt enables for the door bell bits of the other processor (see
13.6.4, “Door Bell Enable Other Processor Register — DBEOR” on page 835
Writing the Door Bell Assertion Register (
Section 13.6.3, “Door Bell Assertion Register
) will set the Door Bell status bits on the other processor.
The Door Bell Registers are interlocked in such a way that the programming model for
them is identical for both integrated processors (Processor 0 and Processor 1). The two
processor’s view of the Door Bell Registers are illustrated in