xr
PRELIMINARY
XRT86VL38
REV. P1.0.6
OCTAL T1/E1/J1 FRAMER/LIU COMBO
340
Figure 47 below shows the timing diagram of the output signals associated with the DS1 Receive Overhead
Output Interface module in T1DM framing format mode.
6.3
E1 Overhead Interface Block
The XRT86VL38 has the ability to extract or insert E1 data link information from or into the E1 National bit
sequence. The source and destination of these inserted and extracted data link bits would be from either the
internal HDLC Controller or the external device accessible through E1 Overhead Interface Block. The
operation of the Transmit Overhead Input Interface Block and the Receive Overhead Output Interface Block
will be discussed separately.
6.4
E1 Transmit Overhead Input Interface Block
6.4.1
Description of the E1 Transmit Overhead Input Interface Block
The E1 Transmit Overhead Input Interface Block will allow an external device to be the provider of the E1
National bit sequence. This interface provides interface signals and required interface timing to shift in proper
data link information at proper time.
The Transmit Overhead Input Interface for a given Framer consists of two signals.
•
TxOHClk_n: The Transmit Overhead Input Interface Clock Output signal
•
TxOH_n: The Transmit Overhead Input Interface Input signal.
The Transmit Overhead Input Interface Clock Output pin (TxOHCLK_n) generates a rising clock edge for each
National bit that is configured to carry Data Link information according to setting of the framer. The Data Link
equipment interfaced to the Transmit Overhead Input Interface should update the data link bits on the TxOH_n
line upon detection of the rising edge of TxOHClk_n. The Transmit Overhead Input Interface block will sample
and latch the data link bits on the TxOH_n line on the falling edge of TxOHClk_n. The data link bits will be
included in and transmitted via the outgoing E1 frames.
The figure below shows block diagram of the DS1 Transmit Overhead Input Interface of XRT86VL38.
F
IGURE
47. DS1 R
ECEIVE
O
VERHEAD
O
UTPUT
I
NTERFACE
T
IMING
IN
T1DM F
RAMING
F
ORMAT
MODE
F
IGURE
48. B
LOCK
D
IAGRAM
OF
THE
E1 T
RANSMIT
O
VERHEAD
I
NPUT
I
NTERFACE
OF
XRT86VL38
Transmit
Overhead Input
Interface
TxOH_n
TxOHClk_n
To Transmit
Framer Block