XRT72L56 Datasheet, PDF (24/486 Pages) Exar Corporation – SIX CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L56
SIX CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. P1.1.2
áç
PRELIMINARY
PIN DESCRIPTION FOR THE XRT72L56
PIN #
A14
A15
A16
A17
PIN NAME
TxOHEnable[0]/
TxHDLCDat7[0]
TxOH[0]/
TxHDLCDat5[0]
TxOHIns[0]/
TxHDLCDat4[0]
RxOHEnable[5]/
RxHDLCDat5[5]
TYPE
O
I
I
I
O
DESCRIPTION
Transmit Overhead Enable:
The XRT72L56 will assert this signal, for one “TxInClk” period, just prior to
the instant that the “Transmit Overhead Data Input Interface” will be sam-
pling 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 -Channel 0, bit 7:
This pin accepts bit 7 TxHDLC data when the HDLC controller is turned on.
Transmit Overhead Input:
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
Transmit 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 -Channel 0, bit 5:
This pin accepts bit 5 TxHDLC data when the HDLC controller is turned on.
Transmit Overhead Data Insert Input:
When “high”, the values on the TxOH line are inserted into the overhead
locations in the place of internally generated data. 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" sig-
nal.
Setting this pin "low" configures the "Transmit Overhead Data Input Inter-
face" NOT to sample the data at the "TxOH" input pin, on the falling edge of
the "TxOHClk" signal.
NOTE: If the Terminal Equipment attempts to insert an overhead bit that
cannot 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 -Channel 0, bit 4:
This pin accepts bit 4 TxHDLC data when the HDLC controller is turned on.
Receive Overhead Enable Indicator:
When “high”, external overhead interface can read the new OH bit placed
on the RxOH line by the framer. Is high for one clock period of RxoutClk.
Receive HDLC Data Output - Channel5, bit 5:
This pin contains bit 5 RxHDLC data when the HDLC controller is turned on.
5