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Serial I/O Architecture Loss-of-Synchronization Procedure and Condition that Cause Acquisition of Synchronization

IP.com Disclosure Number: IPCOM000124008D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-05

Publishing Venue

IBM

Related People

Fredericks, KJ: AUTHOR [+5]

Abstract

Disclosed is the architecture that provides a universal procedure for determining that a serial receiver has lost character synchronization. This architecture has been developed such that it is not peculiar to one specific implementation; that is, an M and N counter design as described in (*). Disclosed is the architecture that describes the condition that causes a serial receiver to acquire character synchronization and the determination of code-violation errors.

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This is the abbreviated version, containing approximately 19% of the total text.

Serial I/O Architecture Loss-of-Synchronization Procedure and Condition
that Cause Acquisition of Synchronization

      Disclosed is the architecture that provides a universal
procedure for determining that a serial receiver has lost character
synchronization.  This architecture has been developed such that it
is not peculiar to one specific implementation; that is, an M and N
counter design as described in (*).  Disclosed is the architecture
that describes the condition that causes a serial receiver to acquire
character synchronization and the determination of code-violation
errors.

      Whenever a signal is present on a link, the receiver attempts
to achieve synchronization on both bit and transmission-character
boundaries of the received encoded bit stream.  Bit synchronization
is achieved when the receiver has identified the start of each bit of
the received signal. The method of achieving bit synchronization is
model-dependent. Synchronization failures on either bit or
transmission-character boundaries are not separately identifiable and
cause loss-of-sync link-signal errors.

      Synchronization to transmission-character boundaries, hereafter
referred to as "synchronization", is achieved when the receiver has
identified the transmission-character boundary as the one that is
established by the input signal from the transmitter at the other end
of the link.  When this condition is achieved, the receiver is in the
"synchronization-acquired" state.  When the transmission-character
boundary identified by the receiver no longer matches the boundary
established by the transmitter to which it is connected, the receiver
is in the "loss-of-synchronization" state.  When the receiver is
operational, it is always in one of these two states.

      Loss-of-Synchronization Procedure:

      The loss-of-synchronization procedure defines the method by
which the receiver changes from the synchronization-acquired state to
the loss-of-synchronization state.  The procedure tests each received
transmission character to determine whether the transmission
character is valid or invalid as defined in Figs. 2 and 3.

      Starting in the synchronization-acquired state, the procedure
checks each transmission character to determine if the character is
valid or invalid. The procedure continues checking the transmission
characters and remains in the synchronization-acquired state, until
four invalid transmission characters are detected according to the
following rules, which use these five detection states:
      1. Detection of no invalid transmission characters
      2. Detection of the first invalid transmission character
   3. Detection of the second invalid transmission character
   4. Detection of the third invalid transmission character
   5. Detection of the fourth invalid transmission character
(Loss-of-Synchronization State)

      When the procedure is in detection state 1, checking for an
invalid tr...