TABLE 2: GS9021 Case Table
MODE
CASE
NUMBER
EDH
PACKET
R/T
CRC_MODE
RESULTS
COMMENTS / SUGGESTIONS
TX MODE
1
2
0
0
0
0
NO
No EDH comparison is performed.
A new EDH packet is inserted into
the data stream with all the EDH
flags cleared unless overwritten by
the dedicated flag port or the host
interface. The EDH packet will
include CRC values calculated
from the data stream.
Use this MODE if you wish to
insert EDH if it is not present. If
EDH is present, clear all flags and
update CRC.
YES
CRC MODE
3
4
X
X
1
1
NO
Same results as Case #1
Use this MODE on the output EDH
chip when mapping flags from an
input EDH chip around a
YES
No EDH comparison is performed
(i.e. no attempt is made to detect
errors). The CRC is updated and
all flags preserved or unaltered
unless overwritten by the
processing core (which would
alter the picture data) to an output
EDH chip so that EDH errors are
not generated. You can also use
this mode when you simply want
to update the CRC values after
processing, if the processing
does not corrupt the EDH packet.
In both cases, the EDH flags are
preserved.
dedicated flag port or host
interface.
RX MODE
5
1
0
NO
New EDH packet inserted into
data stream with all error flags
cleared and all UES flags set high
unless overwritten by the
dedicated flag port or the host
interface.
Use this MODE when you wish to
detect errors in the data stream,
or on an input EDH chip when
mapping flags around a
processing core (that would alter
the picture data) to an output EDH
chip so that EDH errors are not
generated due to the data
processing.
6
1
0
YES
EDH comparison performed and
error flags set and mapped
appropriately unless overwritten
by the dedicated flag port or the
host interface. The CRC is
updated and the EDH packet is re-
inserted.
Use this MODE when you want to
insert EDH if it is not present or
update CRC values and preserve
the flags in an existing EDH
packet.
NOTE
1. “X” in the table above means ‘don’t care’ (but not left floating).
DIN [9:0]
1
2
3
4
5
6
7
8
1
2
3
t
DOUT [9:0]
PCLK IN
LAT
Fig. 3 Data Latency through the GS9021
18
521 - 65 - 05
GENNUM [ GENNUM CORPORATION ]
