XRT72L58 Datasheet, PDF (25/486 Pages) Exar Corporation – EIGHT CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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PRELIMINARY
XRT72L58
EIGHT CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. P1.1.2
PIN DESCRIPTION FOR THE XRT72L58
PIN #
A14
PIN NAME
TxOHEnable[0]/
TxHDLCDat7[0]
A15
TxOH[0]
TxHDLCDat5[0]
A16
TxOHIns[0]/
TxHDLCDat4[0]
A17 RxOHEnable[5]/
RxHDLCDat5[5]
TYPE
O
I
I
I
O
DESCRIPTION
Transmit Overhead Input Enable:
The XRT72L58 will assert this signal, for one “TxInClk” period, just prior to the
instant that the “Transmit Overhead Data Input Interface” will be sampling and
processing an overhead bit.
If the Terminal Equipment intends to insert its own value for an overhead bit,
into the outbound DS3 or E3 frame, it is expected to sample the state of this
signal, upon the falling edge of “TxInClk”. Upon sampling the “TxOHEnable”
high, the Terminal Equipment should (1) place the desired value of the over-
head bit, onto the “TxOH” input pin and (2) assert the “TxOHIns” input pin.
The Transmit Overhead Data Input Interface” block will sample and latch the
data on the “TxOH” signal, upon the rising edge of the very next “TxInClk”
input signal.
Transmit HDLC Data Input - 7:
This pin accepts bit 7 TxHDLC data when the HDLC controller is turned on.
Transmit Overhead Input Pin:
The Transmit Overhead Data Input Interface accepts the overhead data via
this input pin, and inserts into the "overhead" bit position within the very next
"outbound" DS3 or E3 frame. If the "TxOHIns" pin is pulled "high", the Trans-
mit Overhead Data Input Interface will sample the data at this input pin
(TxOH), on the falling edge of the "TxOHClk" output pin. Conversely, if the
"TxOHIns" pin is pulled "low", then the Transmit Overhead Data Input Inter-
face will NOT sample the data at this input pin (TxOH). Consequently, this
data will be ignored.
Transmit HDLC Data Input - 5:
This pin accepts bit 5 TxHDLC data when the HDLC controller is turned on.
Transmit Overhead Data Insert Input:
Asserting this input signal (e.g., setting it "high") enables the Transmit Over-
head Data Input Interface to accept "overhead" data from the Terminal Equip-
ment. In other words, while this input pin is "high", the Transmit Overhead
Data Input Interface will sample the data at the "TxOH" input pin, on the falling
edge of the "TxOHClk" output signal.
Conversely, setting this pin "low" configures the "Transmit Overhead Data
Input Interface" to NOT sample (e.g., ignore) the data at the "TxOH" input pin,
on the falling edge of the "TxOHClk" output signal.
NOTE: If the Terminal Equipment attempts to insert an overhead bit that can-
not be accepted by the "Transmit Overhead Data Input Interface" (e.g., if the
Terminal Equipment asserts the "TxOHIns" signal, at a time when one of
these "non-insertable" overhead bits are being processed); that particular
insertion effort will be ignored.
Transmit HDLC Data Input - 4:
This pin accepts bit 4 TxHDLC data when the HDLC controller is turned on.
Receive Overhead Enable Indicator:
The XRT72L58 will assert this output signal for one “RxOutClk” period when it
is safe for the Terminal Equipment to sample the data on the “RxOH” output
pin.
Receive HDLC Data Output - 5:
This pin contains bit 5 RxHDLC data when the HDLC controller is turned on.
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