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Circuit Pack Descriptions
7-4 Issue 3 June 2001
An optical switch on the circuit pack latch causes a suspension of controller
operations and an “F” to be displayed on the controller panel display when the
latch is pulled. Closing the latch causes a controller reset. Controls and indicators
are discussed in more detail under "User Panel" in Section 6, "Operations
Interfaces."
General Description of Operation 7
The SYSCTL circuit pack provides the majority of the control functions on the
shelf. These include circuit pack monitoring, PM, protection switching, and user
interfaces.
The SYSCTL, which contains a microprocessor, controls links to all other circuit
packs in the system and links to user interfaces. The processor also provides link
access procedure (LAPD) and LAPD packet data processing to support SONET
section DCC.
Detailed Description of Operation 7
Control Circuitry 7
Processor. 7Figure 7-2 provides an overall block diagram of the SYSCTL circuit
pack. This processor is the highest level processor in the system.
Memory 7
Program Flash-EPROM . 7The main program is stored in the flash-EPROM, which
combines the nonvolatility of EPROM with the in-circuit reprogramming ability of
electrically erasable programmable read-only memory (EEPROM). Electrically
Erasable Programmable Read-Only Memory FEPROM allows in-service software
upgrades to be performed locally or remotely without replacing the SYSCTL
circuit pack. Program upgrades of remote DDM-2000 OC-3 shelves can also be
done via the DCC. Of course, software upgrades may also be accomplished by
replacing circuit packs with packs that have already had software upgrades.
RAM. 7The main processor's random access memory (RAM) is used to store all
volatile information, such as system alarms, PM information, and parameters, for
the main processor's operating system.
EEPROM. 7Allnonvolatileparameters,suchasprovisioning,arestoredinthe
EEPROM, which maintains its data indefinitely during a power loss.
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