918 NTAK20 Clock Controller daughterboardIf the command "free run" is given, the clock controller enters the free-runmode and remains there until a new command is received. Note that thefree-run mode of operation automatically initiates after the clock controllerhas been enabled.In the temporary absence of a synchronization reference signal, or whensudden changes occur on the incoming reference due to error bursts, theclock controller provides a stable holdover. Free-run mode is initiated whenthe clock controller has no record of the quality of the incoming referenceclock.If the command "free run" is given, the clock controller enters the free-runmode and remains there until a new command is received. Free-runautomatically initiates after the clock controller has been enabled.CPU-MUX bus interfaceA parallel I/O port on the clock controller provides a communication channelbetween the clock controller and the CPU.A parallel I/O port on the clock controller. provides a communication channelbetween the clock controller and the CPU.A parallel I/O port on the clock controller provides a communication channelbetween the clock controller and the CPU.Signal conditioningDrivers and buffers are provided for all outgoing and incoming lines.Drivers and buffers are provided for all outgoing and incoming lines.Drivers and buffers are provided for all outgoing and incoming lines.Sanity timerThe sanity timer resets the microprocessor in the event of system hang-up.sanity timer resets the microprocessor in the event of system hang-up.The sanity timer resets the microprocessor in the event of system hang-up.MicroprocessorThe microprocessor does the following:• communicates with software• monitors two references• provides a self-test during initializationNortel Communication Server 1000Circuit Card ReferenceNN43001-311 01.04 StandardRelease 5.0 23 May 2008Copyright © 2003-2008, Nortel Networks.
