
XRT86SH221
PRELIMINARY
15
SDH-TO-PDH FRAMER/MAPPER WITH INTEGRATED 21-CHANNEL E1 SH LIU
REV. P1.0.5
1.8
HIGH SPEED SECTION AND PATH OVERHEAD BUS
388 B
ALL
568 B
ALL
P
IN
N
AME
T
YPE
D
ESCRIPTION
Receive Section and Path Overhead Extraction Bus
V3
AA3
RxOH
O
Receive SOH/POH Data Output Port
The extracted SOH/POH overhead bytes will be updated on this
output pin on the falling edge of RxOHCLK. Therefore, RxOH
should be sampled using the rising edge of RxOHCLK.
Y1
W5
RxOHCLK
O
Receive SOH/POH Overhead Clock Output
This output clock signal is used as the timing reference for the
Receive Overhead Extraction Bus. This clock will update all out-
put extraction bus pins on its falling edge.
V4
Y5
RxOHFRAME
O
Receive SOH/POH Overhead Frame Boundary Indicator
The Receive SOH/POH Data Output Port will pulse this output
pin "High" for one period of RxOHCLK, coincident to whenever it
is extracting the very first bit of the STM-0/STM-1 frame in the
Section Overhead (A1) and the very first bit of the Path Over-
head (J1). If RxPOH_IND is "Low" during this Frame Pulse, then
that bit is A1. If RxPOH_IND is "High" during this Frame Pulse,
then that bit is J1. This pin will be pulled "Low" at all other times.
U4
Y4
RxOHVALID
O
Receive SOH/POH Overhead Data Valid Indicator
This output pin will be pulled "High" when the extracted SOH and
POH bytes are ready to be sampled from the overhead bus. This
pin will be pulled "Low" at all other times. If RxPOH_IND is "Low"
while RxOHVALID is "High", then SOH is valid. If RxPOH_IND is
"High" while RxOHVALID is "High", then POH is valid. This pin
will be pulled "Low" at all other times.
W3
AB3
RxPOH_IND
O
Receive POH Indicator
The Receive Path Overhead Indicator will pull "High", coincident
to whenever it is extracting Path Overhead data via the RxOH
output pin. Conversely, this pin will pull "Low", coincident to
whenever it is extracting Section Overhead data via the RxOH
output pin. This pin will be updated on the falling edge of RxO-
HCLK.
Transmit Section and Path Overhead Insertion Bus
K4
E1
TxOHEN
O
Transmit SOH/POH Overhead Port Enable Output
The state of this output pin determines the time period when the
XRT86SH221 can accept SOH/POH overhead bytes. The Over-
head Insertion Bus is active when this pin is pulled "High".
G2
F2
TxOH
I
Transmit SOH/POH Data Input Port
If the System Side Terminal Equipment intends to insert its own
value for a given overhead SOH or POH byte into the outbound
STM-0 or STM-1 data-stream, then the System Side Terminal
Equipment is expected to apply the overhead bytes to this input
pin while asserting the TxOHINS input pin. This input pin is sam-
pled upon the rising edge of TxOHCLK.
G1
H3
TxOHCLK
O
Transmit SOH/POH Overhead Clock Output
This output clock signal is used as the timing reference for the
Transmit Overhead Insertion Bus. This clock will sample all input
insertion bus pins on its rising edge.