GX3202 Datasheet, PDF(30/49 Page) Semtech Corporation – Crosspoint Switch with Trace Equalization and Output De-emphasis

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GX3202 Datasheet, PDF (30/49 Pages) Semtech Corporation – Crosspoint Switch with Trace Equalization and Output De-emphasis

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3. The pattern generator locked, but the number of errors observed exceeded the

value indicated by the RX0_PRBS_BER_THRESH bits. This error is detectable if

RX0_PRBS_LOCK and RX0_PRBS_FAIL are both HIGH, and the value of

RX0_PRBS_ERROR_COUNT is equal or greater than the value in

RX0_PRBS_BER_THRESH.

Note that the values of RX0_PRBS_LOCK and RX1_PRBS_LOCK, RX0_PRBS_PASS

and RX1_PRBS_PASS, RX0_PRBS_FAIL and RX1_PRBS_FAIL,

RX0_PRBS_ERROR_COUNT and RX1_PRBS_ERROR_COUNT are reset whenever

any of the corresponding test parameters for the RX0 and RX1 pattern checkers are

updated as well as whenever the corresponding RX0_PRBS_ENABLE or

RX1_PRBS_ENABLE bits are set to '1' when previously set to '0'. To start a new PRBS test

when the previous one has already been run, either re-write

RX0_PRBS_BER_TIME/RX1_PRBS_BER_TIME or toggle

RX0_PRBS_ENABLE/RX1_PRBS_ENABLE.

NOTE: The pattern checkers will count zero errors if the incident data is simply a static

zero.

4.7 Horizontal Eye Measurement

As explained above, the GX3202 enables the measurement of bit error âbathtubâ curves

at the video rates of 1485Mb/s and 2970Mb/s to assist in evaluating how much margin

there is in the system.

See Using the Monitoring Features of the GX3290 Application Note for more

information.

4.7.1 Configuration for Horizontal Eye Measurement

â¢ Route the input signal of interest to the MON0 or MON1 of the matrix

â¢ Route the monitor output of matrix to pattern checker Rx, (RX0 in the notes below)

by setting the RX0_CHECK_KEY_D2A bits to 0

â¢ For a PRBS pattern, select a pattern length with a value of the

RX0_PRBS_POLYNOMIAL bits set to match the source pattern, and set the

RX0_PRBS_CHK_MODE bits to 1 to select the phase interpolator path

â¢ For an arbitrary pattern, set the RX0_PRBS_CHK_MODE bits to 2 to select the

direct data comparison mode

â¢ Set initial sampling phase with the

RX0_PHASE_INTERPOLATOR_PHASE_SEL_D2A bits (in the BIST_RX_4 register)

â¢ Initiate error counting as described in Section 4.6.2 above

â¢ Increment the sampling phase

â¢ Count errors

â¢ Repeat last two steps to cover one UI

GX3202 202 x 202 3.5Gb/s Crosspoint

Data Sheet

56077 - 1

October 2012

30 of 49

Proprietary & Confidential

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