xr
XRT94L33
3-CHANNEL DS3/E3/STS-1 TO STS-3/STM-1 MAPPER IC DATA SHEET
Rev.1.2.0.
247
Afterwards, the “external circuit” should serially place the remaining seven bits (of the Z3 byte) onto the
“TxPOH_n” input pin, upon each of the next seven falling edges of “TxPOHClk_n”.
The “external circuit” should then revert back to continuously sampling the states of the “TxPOHEnable_n”
and “TxPOHFrame_n” output pins and repeat the above-mentioned process.
2.2.7.3.9
SUPPORT/HANDLING OF THE Z4 BYTE
The Transmit STS-3c POH Processor block permits the user to control the value of the Z4 byte by either of
the following options.
Setting and controlling the “outbound” Z4 Byte via Software
Setting and controlling the “outbound” Z4 Byte via the “TxPOH Input Port”
The details and instructions for using either or these features are presented below.
2.2.7.3.9.1
Setting and Controlling the Outbound Z4 Byte via Software
The Transmit STS-3c POH Processor block permits the user to specify the contents of the Z4 byte, within the
“outbound” STS-3c SPE via software command.
The user can configure the Transmit STS-3c POH Processor block to accomplish this by performing the
following steps.
STEP 1 – Write the value “0” into Bit 0 (Z4 Insertion Type) within the “Transmit STS-3c Path – SONET
Control Register – Byte 1”, as depicted below.
Transmit STS-3c Path – SONET Control Register – Byte 1 (Address = 0x1982)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
Z5 Insertion
Type
Z4 Insertion
Type
Z3 Insertion
Type
H4 Insertion
Type
R/O
R/W
0
This step configures the Transmit STS-3c POH Processor block to read out the contents of the “Transmit
STS-3c Path – Transmit Z4 Byte Value” register; and load this value into the Z4 byte position within each
“outbound” STS-3c SPE.
STEP 2 – Write the desired byte value (for the outbound H4 byte) into the “Transmit STS-3c Path –
Transmit Z4 Byte Value” register.
The bit-format of this register is presented below.
Transmit STS-3c Path – Transmit Z4 Byte Value Register (Address = 0x19AF)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Transmit_Z4_Byte_Value[7:0]
R/W
0
2.2.7.3.9.2
Setting and Controlling the Outbound Z4 Byte via the “TxPOH_n Input Port”
The Transmit STS-3c POH Processor block permits the user to specify the contents of the Z4 byte, within the
“outbound” STS-3c SPE, via data applied to the “TxPOH_n” input pin.
The user can configure the Transmit STS-3c POH Processor block to accomplish this by performing the
following steps.