XRT84L38IB Exar Corporation, XRT84L38IB Datasheet - Page 235

• Manufacturer Part Number: XRT84L38IB
• Description: Network Controller & Processor ICs 8 Ch T1/E1 Framer
• Manufacturer: Exar Corporation

Specifications of XRT84L38IB

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

REV. 1.0.1
The incoming Receive Payload Data is taken into the framer from the LIU interface using the Recovered
Receive Line Clock. The payload data is then routed through the Receive Farmer Module and presented to the
Receive Payload Data Output Interface through the Receive Serial Data output pin (RxSer_n). This data is
then clocked out using the Receive Serial Clock (RxSerClk_n).
There is a two-frame (512 bits) elastic buffer between the Receive Framer Module and the Receive Payload
Data Output Interface. This buffer can be enabled or disabled via programming the Slip Buffer Enable [1:0] bits
in Slip Buffer Control Register (SBCR).
The following table shows configurations of the Slip Buffer Enable [1:0] bits in Slip Buffer Control Register.
SLIP BUFFER CONTROL REGISTER (SBCR) (INDIRECT ADDRESS = 0xn0H, 0x16H)
If the Slip Buffer is not in bypass mode, then the user has the option of either providing the Receive Single-
Frame Synchronization pulse or getting the Receive Single-Frame Synchronization pulse on frame boundary
at the RxSync_n pin. The Slip Buffer Receive Synchronization Direction bit of the Slip Buffer Control Register
(SBCR) determines whether the Receive Single-Frame Synchronization signal is input or output.
The table below demonstrates settings of the Slip Buffer Receive Synchronization Direction bit of the Slip
Buffer Control Register.
SLIP BUFFER CONTROL REGISTER (SBCR) (INDIRECT ADDRESS = 0xn0H, 0x16H)
If the Slip Buffer is in bypass mode, the Receive Payload Data is routed to the Receive Payload Data Output
Interface from the Receive Framer Module directly. The Recovered Line Clock is used to carry the Receive
Payload Data all the way from the LIU interface, to the Receive Framer Module and eventually output through
the Receive Serial Data output pin. The Receive Serial Clock signal is therefore an output using the Recovered
Receive Line Clock as timing source. The Receive Single-Frame Synchronization signal is also output in Slip
Buffer bypass mode.
If the Slip Buffer is enabled, the Receive Payload Data is latched into the Elastic Store using the Recovered
Receive Line Clock. The local Terminal Equipment supplies a free-running 1.544MHz clock to the Receive
Serial Clock pin to latch the Receive Payload Data out from the Elastic Store. Since the Recovered Receive
N
N
UMBER
UMBER
B
1-0
B
2
IT
IT
Synchronization
Slip Buffer
B
Slip Buffer
B
Enable
Direction
IT
Receive
IT
N
N
AME
AME
B
IT
R/W
B
T
IT
R/W
YPE
T
YPE
00 - Slip Buffer is bypassed. The Receive Payload Data is passing from the
Receive Framer Module to the Receive Payload Data Output Interface directly
without routing through the Slip Buffer. The Receive Serial Clock signal
(RxSerClk_n) is an output.
01 - The Elastic Store (Slip Buffer) is enabled. The Receive Payload Data is
passing from the Receive Framer Module through the Slip Buffer to the Receive
Payload Data Output Interface. The Receive Serial Clock signal (RxSerClk_n) is
an input.
10 - The Slip Buffer acts as a FIFO. The FIFO Latency Register (FLR) deter-
mines the data latency. The Receive Payload Data is passing from the Receive
Framer Module through the FIFO to the Receive Payload Data Output Interface.
The Receive Serial Clock signal (RxSerClk_n) is an input.
11 - Slip Buffer is bypassed. The Receive Payload Data is passing from the
Receive Framer Module to the Receive Payload Data Output Interface directly
without routing through the Slip Buffer. The Receive Serial Clock signal
(RxSerClk_n) is an output.
0 - The Receive Single-Frame Synchronization signal (RxSync_n) is an output
if the Slip Buffer is not in bypass mode.
1 - The Receive Single-Frame Synchronization signal (RxSync_n) is an input
if the Slip Buffer is not in bypass mode.
215
B
B
IT
IT
D
D
ESCRIPTION
ESCRIPTION
OCTAL T1/E1/J1 FRAMER
XRT84L38