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PRELIMINARY
DS3 UNI FOR ATM
XRT7245
REV. 1.03
171
OAM cell into the “Transmit OAM Cell” buffer, the lo-
cal μP must write this data into this address location
within the UNI IC, via the Microprocessor Interface.
Afterwards, whenever the user wishes to transmit the
OAM cell, the local μP must to write a “1” to bit 7
(SendOAM) within the TxCP OAM Register as
depicted below.
If the local μP writes a “1” bit 7 (or 1xxxxxxxb) to the
TxCP OAM Register; then the Transmit Cell Proces-
sor will read-in the contents of the “Transmit OAM
Cell” buffer, and form it into a cell. This OAM cell will
then be routed to the HEC Byte Calculator and Cell
Scrambler within the Transmit Cell Processor block,
prior to transmittal to the Transmit PLCP Processor
(or Transmit DS3 Framer). Bit 7 of the TxCP OAM
Register will be reset (to “0”) upon completion of the
transmission of the OAM cell. The user may also poll
this bit in order to determine whether or not the OAM
cell has been sent.
The user can monitor the number of valid cells (e.g.,
user and OAM cells) that have been generated and
transmitted to the Transmit PLCP Processor or the
Transmit DS3 Framer. The Transmit Cell Processor
increments the contents of the “PMON Transmitted
Valid Cell Count (MSB and LSB)” Registers (Address
= 3Ah, and 3Bh) for each valid cell that it generates.
These two registers are “Reset-upon-Read” registers
that when concatenated present a 16-bit representa-
tion of the total number of “valid cells” generated and
transmitted by the Transmit Cell Processor, since the
last read of these registers. The bit-format of these
two registers follows:
6.2.2.4
Whenever the TxFIFO (within the Transmit UTOPIA
Interface block) does not contain a complete cell, the
Transmit Cell Processor will automatically generate
and process Idle Cells. The user can customize the
contents of these Idle Cells or he/she can use the de-
fault values that are provided by the UNI chip. The
user can customize the contents of these Idle Cells
by programming six different registers:
TxCP Idle Cell Pattern—Header Byte 1
Idle Cell Processing
TxCP Idle Cell Pattern—Header Byte 2
TxCP Idle Cell Pattern—Header Byte 3
TxCP Idle Cell Pattern—Header Byte 4
TxCP Idle Cell Pattern—Header Byte 5
TxCP Transmit Cell Payload
Table 18 presents the Bit Format of each of these
Registers and Table 19 presents the Address and
Default values of these cells.
TxCP OAM Register (Address = 61h)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
SendOAM
Unused
Semaphore
RO
RO
RO
RO
RO
RO
RO
PMON Transmitted Valid Cell Count—MSB (Address = 3Ah)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Tx Valid Cell Count—High Byte
RUR
RUR
RUR
RUR
RUR
RUR
RUR
RUR
0
0
0
0
0
0
0
0
PMON Transmitted Valid Cell Count—LSB (Address = 3Bh)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Tx Valid Cell Count—Low Byte
RUR
RUR
RUR
RUR
RUR
RUR
RUR
RUR
0
0
0
0
0
0
0
0