VSC3138
Datasheet
This enables the error counters in the Detector. The user has the option to choose the period over which errors are counted
by setting the Error Counter Length bits [2:1] of the PRBS Detector Configuration register. Respectively, the Error
Counter Length bits [2:1] represent the following count lengths: 00=2
7
, 01=2
9
, 10=2
11
, 11=2
15
.
When any one of the above periods is selected, the error count will continue until that period has elapsed. At that time the
error counter will hold its count and the Period Indicator bit [1] of the PRBS Error Status register will be set to 1 to
indicate the count period is complete. If the Error Flag bit [0] in the PRBS Error Status register is set to 1, it means that
during the set time period, errors occurred and the error count is stored in the PRBS Error Count Read registers 0x267’h
and 0x287’h. The error counter can be reset by strobing the Error Detect Reset bit [3] of the PRBS Detector Configuration
register LOW. The Error Detect Reset bit [3] of the PRBS Detector Configuration register should be set HIGH while the
detector is enabled.
Upon reset, the Fixed Error Count Period Indicator bit [1] and the Error Flag bit [0] of the PRBS Error Status register, and
PRBS Error Count bits [7:0] of the PRBS Error Count Read register will be set to 0. The user can read errors without
setting the error count period by setting the Error Detection Run Length bit [0] of the PRBS Detector Configuration
register 0x285’h to 0. If the error count period is not set, and if the number of errors exceeds 65535 (counter overflow), the
error counter will restart the count from 0. It is possible to invert the PRBS pattern that is entering into the pattern detector
by setting the PRBS Input Pattern bit [4] of the PRBS Detector Configuration register 0x285’h to 1. This can be used to
detect an inverted pattern from the PRBS Generator.
illustrates how the PRBS function can be connected to the switch core for signal path tracing to and from the
switch. Refer to Figure 3 and use the following set of steps to effect a trace.
1.
Connect PRBS_OUT and PRBS_OUTB to DRIVE0 and DRIVE0B, respectively.
2.
Connect SENSE0 and SENSE0B to PRBS_IN and PRBS_INB, respectively.
3.
Select channel to send the pattern through.
4.
Generate the pattern with the PRBS generator.
5.
Check the PRBS Detector for errors.
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G52414 Revision 4.2
March 8, 2006
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
