mt90868ag2 Zarlink Semiconductor, mt90868ag2 Datasheet - Page 32

• Manufacturer Part Number: mt90868ag2
• Description: 32,768 X 8,192 Channels High Bandwidth Digital Switch With Up To 128 Streams On Backplane And 128 Streams On Local And Data Rates From 8 To 32 Mbps
• Manufacturer: Zarlink Semiconductor

backplane connection memory respectively and also setting the SBERL bit (for local) or the SBERB bit (for
backplane) in the Control Register (CR) to high.
For the test, the users can program the BER pattern for multiple consecutive output channels through the connection
memory. However, the number of consecutive output channels must be the same as the number of input channels
defined in the local and backplane BER length registers (LBLR and BBLR) which define how many BER channels
to be monitored by the BER receivers.
There are three types of registers to control the BER transmitter and receiver circuits. The BER Start Receive
Registers for the local (LBSRR) and the backplane (BBSRR) define the input stream and channel from where the
BER sequence will start to compare. The BER Length Registers for the local (LBLR) and the backplane (BBLR)
define the number of input channels which the sequence will be last. The BER Count Registers for the local (LBCR)
and the backplane (BBCR) contain the number of counted BER errors after the comparison. To prevent overflow,
the internal BER counter will stop updating the error count when the error count reaches 0xFFFF. In additional to
the BER registers, the CBERL bit and the CBERB bit of the Control Register are used to clear the backplane and
the local bit error count registers; the SBERB and SBERL are used to enable the backplane and the local BER
transmitters and receivers. See Table 24, 25, 26, 27, 28 and 29 for the detailed descriptions of the BER registers.
The BER test should be carried out as follows:
•
•
•
•
•
•
•
(Note : The transmitter and receiver for both local and backplane interface can be controlled independently to each
other.)
When the backplane port is in the 32Mb/s mode, the bit error rate test mode is not available for the backplane output
streams
the BER test mode. Figure 17 explains the details. When the backplane port is in the 16Mb/s mode, all backplane
output streams are available.
32
Set the SBERB and the SBERL bits to zero to disable the backplane and the local BER transmitters during
the programming of the backplane and local connection memories for the BER test; when the BER
transmitters are disabled, the transmitter outputs are set to zero,
Set the SBERB and SBERL bit from zero to one to enable the BER transmitters and receivers upon the
completion of the programming of the connection memories,
Allow the BER transmitters and receivers to run for at least two frames (or the delay between the serial data
output and the serial date input) before the BER receivers can correctly identify errors in the BER pattern
but ignore the error counts displayed in the BER count registers during this training period,
After the training period, clear the BER count registers by setting the CBERL and the CBERB bit of the
control register from zero to one,
Set the CBERL and CBERB bits from one to zero to release the BER counter; the BER receivers receive
the BER sequence and perform the comparison,
Record the bit errors by reading the BER count registers upon the completion of the BER test,
Clear the BER counters by setting the CBERB and CBERL from zero to one upon the completion of the
BER test,
BSTo 0, 2,
BSTo 1, 3,
BSTo0, 1, 4, 5, 8, 9,
Figure 17 - Backplane Output Streams Availability for BER Test at 32Mb/s mode
4, 6,
5, 7,
8, 10,
9, 11,
... ,
To enable the bit error rate test for the unshaded channels,
one of the shaded channels on their right hand side has to be enabled.
Example: To enable Ch8 for BER test mode, Ch10 or Ch11 has to be enabled.
The bit error rate test mode is available for the shaded channels.
4n
12,
13,
+
0
,
... ,
... ,
4n
+
56, 58, 60,
57, 59, 61,
1
unless the output stream
Zarlink Semiconductor Inc.
62.
63.
4n
+
2
or
4n
+
3
(for
0 n 15
≤ ≤
Data Sheet
)
is enabled for