STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
signal and greater than 7 bits long for a B8ZS-coded signals. The inclusion of
excessive zeros in the line code violation count can be disabled.
For E1, a line code violation is defined as a bipolar violation (BPV) for AMI-coded
signals and is defined as a bipolar violation of the same polarity as the last
bipolar violation for HDB3-coded signals.
Generation of the transfer clock within the COMET chip is performed by writing
to any counter register location or by writing to the Global PMON Update register.
The holding register addresses are contiguous to facilitate faster polling
operations.
9.8
T1 Bit Oriented Code Detector (RBOC)
The Bit Oriented Code detection function is provided by the RBOC block. This
block detects the presence of 63 of the possible 64 bit oriented codes
transmitted in the Facility Data Link channel in ESF framing format, as defined in
th
ANSI T1.403-1993 and in TR-TSY-000194. The 64 code (111111) is similar to
the DL FLAG sequence and is used by the RBOC to indicate no valid code
received.
Bit oriented codes are received on the Facility Data Link channel as a 16-bit
sequence consisting of 8 ones, a zero, 6 code bits, and a trailing zero
(111111110xxxxxx0) which is repeated at least 10 times. The RBOC can be
enabled to declare a received code valid if it has been observed for 8 out of 10
times or for 4 out of 5 times, as specified by the AVC bit in the control register.
Valid BOC are indicated through an internal status register. The BOC bits are set
to all ones (111111) if no valid code has been detected. An interrupt is generated
to signal when a detected code has been validated, or optionally, when a valid
code goes away (i.e. the BOC bits go to all ones).
9.9
HDLC Receiver (RDLC)
The HDLC Receiver function is provided by the RDLC block. The RDLC is a
microprocessor peripheral used to receive HDLC frames. Three RDLC blocks
are provided for flexible extraction of standardized data links:
• T1 ESF facility data link
• T1DM data link
• ISDN D-channel
• E1 Common Channel Signaling data link
PROPRIETARY AND CONFIDENTIAL
48
PMC [ PMC-SIERRA, INC ]
