PM73121ꢀAAL1gator II
Data Sheet
PMC-Sierra, Inc.
PMC-980620
,VVXHꢀꢁ
AAL1 SAR Processor
Figure 45 shows the contents of the receive signaling buffer with an E1 line in the SDF-MF mode
with T1 signaling. Even channel bytes are stored in the low-byte end of the data words.
Byte Address
Multiframe
Channel 30 Channel 31
ABCD
ABCD
Channel 1
ABCD
Channel 0
ABCD
0
15
Figure 45. E1 SDF-MF Mode with T1 Signaling Format of the R_SIG_BUFFER
3.6.1 Handling Data and Signaling Bytes in a Structure
A data structure consists of all of the data bytes for that structure, followed by all of the signaling
bytes for that structure, if any. In order to locate the data and signaling bytes, the following mem-
ory structures are used:
•
The R_TOT_SIZE structure provides the number of data and signaling bytes in a
structure. An element can be a data byte or a signaling nibble. This value is initialized by
the microprocessor.
•
•
The R_TOT_LEFT structure provides the running count of the number of bytes remaining
in the structure.
The R_DATA_LAST structure identifies the last byte of the data structure. As the data
bytes are stored in memory, the R_TOT_LEFT structure is decremented by one. When R_
TOT_LEFT is equal to R_DATA_LAST, it indicates the end of the data structure. The
remaining bytes are stored in the R_SIG_QUEUE. The signaling nibbles are written to the
memory until the R_TOT_LEFT equals zero. Once R_TOT_LEFT is zero, R_TOT_SIZE
is copied to R_TOT_LEFT and the storing of data and signaling structures is repeated. R_
TOT_SIZE and R_DAT_LAST are initialized by the microprocessor.
•
The structure used for signaling is determined by the mode of the line and the value of E1_
WITH_T1_SIG (refer to “E1_WITH_T1_SIG” on page 126). Normally the signaling
structure will follow the mode of the line. However if the line is in E1 mode and E1_
WITH_T1_SIG is set, then a T1 signaling structure is used. This means that for a single
DS0, signaling is updated after 24 data bytes instead of after 16 data bytes.
ꢄꢈ
PMC [ PMC-SIERRA, INC ]
