RCIM User’s Guide
3-14
Distributed ETIs
1
Any or all of the ETIs on an RCIM can be distributed to all systems connected by an
RCIM chain. The source of a distributed ETI can be located on any of the RCIMs in the
chain.
To determine if a specified ETI has its interrupts sent to all connected systems, use one of
the methods described in the section entitled “Obtaining RCIM Values” on page 3-11. See
the “Distributed Interrupts” section on page 3-17 for information about setting up
distributed interrupts.
Real-Time Clocks (RTCs)
1
The RCIM provides real-time clock timers. Each of these counters is accessible using a
special file and each can be used for almost any timing or frequency control function.
RCIM III and RCIM II support eight 32-bit RTCs (0-7); RCIM I supports four (0-3).
The real-time clock timers are programmable to several different resolutions which, when
combined with a clock count value, provide a variety of timing intervals. This makes them
ideal for running processes at a given frequency (e.g., 600Hz) or for timing code
segments. The timers may be one-shot or periodic; if periodic, the original load value is
automatically reloaded into the counter each time zero is reached.
In addition to being able to generate an interrupt on the host system, the output of an
RCIM real-time counter can be distributed to other RCIM boards for delivery to their
corresponding host systems, or delivered to external equipment attached to one of the
RCIM’s external output interrupt lines.
The
rcim_rtc(4)
man page provides complete information about RTCs.
RTC Device Files
1
Each RTC is accessed through its own special device file:
/dev/rcim
N
/rtc
M
where
N
is the RCIM card number (starting from zero) and
M
is the ID of the RTC.
These files are created automatically on system boot by the
/etc/init.d/rcim
initialization script.
Distributed RTCs
1
Any or all of the RTCs on an RCIM can be distributed to all systems connected by an
RCIM chain. The source of a distributed RTC may be located on any of the RCIMs in the
chain.
To determine if a specified RTC has its interrupts sent to all connected systems, use one of
the methods described in the section entitled “Obtaining RCIM Values” earlier in this
chapter. See the “Distributed Interrupts” section on page 3-17 for information about
setting up distributed interrupts.
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