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XRT94L43
24
REV. 1.0.2
SONET/SDH OC-12 TO 12XDS3/E3 MAPPER
SONET/SDH OVERHEAD INTERFACE - TRANSMIT DIRECTION
PIN #
SIGNAL NAME
I/O
SIGNAL
TYPE
DESCRIPTION
H2
TxTOHClk
O
CMOS
Transmit TOH Input Port - Clock Output:
This output pin, along with the TxTOHEnable, TxTOHFrame output pins
and the TxTOH and TxTOHIns input pins function as the Transmit TOH
Input Port.
The Transmit TOH Input Port allows the user to insert their own value for
the TOH bytes (in the outbound STS-12/STM-4 signal).
This output pin provides a clock signal. If the TxTOHEnable output pin is
"High" and if the TxTOHIns input pin is pulled "High", then the user is
expected to provide a given bit (within the TOH) to the TxTOH input pin,
upon the falling edge of this clock signal. The data, residing on the
TxTOH input pin will be latched into the XRT94L43 upon the rising edge
of this clock signal.
NOTE: The Transmit TOH Input Port only support the insertion of the
TOH within the first STS-1, within the outbound STS-12 signal.
H4
TxTOHEnable
O
CMOS
Transmit TOH Input Port - TOH Enable (or READY) indicator:
This output pin, along with the TxTOHClk, TxTOHFrame output pins and
the TxTOH and TxTOHIns input pins function as the Transmit TOH Input
Port.
This output pin will toggle and remain "High" anytime the Transmit TOH
Input Port is ready to externally accept TOH data.
If it is desired to externally insert a value of TOH into the outbound STS-
12 data stream via the Transmit TOH Input Port, then do the following:
Continuously sample the state of TxTOHFrame and this output pin
upon the rising edge of TxTOHClk.
Whenever this output pin pulses "High", then the user's external
circuitry should drive the TxTOHIns input pin "High".
Next, the user should output the next TOH bit, onto the TxTOH input
pin, upon the falling edge of TxTOHClk.
D1
TxTOH
I
TTL
Transmit TOH Input Port - Input Pin:
This input pin, along with the TxTOHIns input pin, the TxTOHEnable
and TxTOHFrame and TxTOHClk output pins function as the Transmit
TOH Input Port.
If it is desired to externally insert a value of TOH into the outbound STS-
12 data stream via the Transmit TOH Input Port, then do the following:
Continuously sample the state of TxTOHFrame and TxTOHEnable
upon the rising edge of TxTOHClk.
Whenever TxTOHEnable pulses "High", then the user's external
circuitry should drive the TxTOHIns input pin "High".
Next, the user should output the next TOH bit, onto this input pin,
upon the falling edge of TxTOHClk. The Transmit TOH Input Port will
sample the data (on this input pin) upon the rising edge of TxTOHClk.
NOTE: Data at this input pin will be ignored (e.g., not sampled) unless
the TxTOHEnable output pin is "High" and the TxTOHIns input
pin is pulled "High".