RCIM User’s Guide
3-10
Setting up Distributed Interrupts
1
The RCIM provides the ability to share interrupts across interconnected systems using an
RCIM chain. Although distributed interrupts are covered in detail starting on page 3-17,
the figures below provide an illustration of how they operate. Guidelines for setting up
distributed interrupts based on the illustration follow.
Figure 3-2 Distributed Interrupt Operation Example
In Figure 3-2, there are three scenarios:
•
A signal is generated on ETI
3
that drives an interrupt on DI
0
and another on
OUT
3
. The interrupt is also passed to the host system.
•
An interrupt is received from the RCIM chain on DI
7
. This interrupt is sent
to the host system and also sent to an external device via OUT
0
.
•
An interrupt is generated on PIG
0
that is passed to an external device via
OUT
0
.
Note that on RCIM III and RCIM II, the local interrupt does not drive the configured DI.
An
ETI_REQUEST
ioctl will cause a local interrupt but will not affect the DI associated with
the ETI. For example, if ETI
0
is configured to drive DI
0
, it will connect the external ETI
input to DI
0
directly without passing through the local ETI
0
interrupt control logic. A
benefit of this is that a local interrupt is not issued for every distributed PIG and ETI. A
PIG should be used for a programmable software controlled interrupt and an ETI should
be used for an external interrupt output.
Please note the following in this example:
•
A problem can occur when more than one interrupt module tries to drive
the same signal line. In the example, the ETI
3
signal drives the interrupt on
ETI
0
ETI
3
. . .
RTC
0
RTC
3
. . .
PIG
0
PIG
3
. . .
OUT
0
OUT
3
. . .
DI
0
DI
7
. . .
HOST SYSTEM
.
RCIM
Chain
.
.
.
To External
Device
Chain
RCIM
To
From
.
.
. . .
External
Interrupt
Line
. . .
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