GS12281 datasheet(23/97 Pages) SEMTECH

23 / 97 page

GS12281

Final Data Sheet

Rev.9

PDS-061385

February 2019

23 of 97

Semtech

Proprietary & Confidential

www.semtech.com

4.4 PRBS Checker

The GS12281 includes an integrated PRBS checker, which can error check a PRBS7 signal

out of the trace equalizer input blocks.

There are two modes of operation for the PRBS checker:

•

Timed Mode: Used for precise measurements of up to ~3.334s.

 In timed mode, the host sets the measurement time and executes the checker

operation. The device ends the PRBS error check measurement when the timer

expires, and the host reads back the measurement status and error count.

•

Continuous Mode: Can be used for longer measurements but with less precision in

the time interval.

 In continuous mode, the host controls the starts and stops of the PRBS error

checking operation then reads back the measurement status and error count.

Note: When working with the PRBS Checker, please note the following.

•

The parameters referred to in Section 4.4.1 to Section 4.4.2 are briefly described and

linked to their respective registers in Table 4-4. For a complete list of registers and

functions, please see Section 5.

•

The PRBS generator and checker can be active at the same time, however, the

generator can not be looped back on itself for error checking.

4.4.1 Timed PRBS Check Measurement Procedure

For applications where measurement times are ~3.34s or less, the timed PRBS check

mode is the most suitable. Alternatively, to achieve precise timing for lower BER signals,

the timed PRBS check measurement can be repeated by the host and the total

measurement time and error count is determined by summing the individual

measurements.

In timed mode, the host sets the total measurement time by setting the

CFG_PRBS_CHECK_PREDIVIDER and the CFG_PRBS_CHECK_MEAS_TIME

parameters to the required values to achieve the total measurement time required by

the application.

To perform a timed PRBS measurement, please complete the following steps:

1. Set the appropriate settings within CFG_PRBS_CHECK_PREDIVIDER and

CFG_PRBS_CHECK_MEAS_TIME to achieve the total measurement time required

by the application. The TMT (total measurement time) is determined by the

following equation:



TMT = CFG_PRBS_CHECK_PREDIVIDER * (CFG_PRBS_CHECK_MEAS_TIME

*256+1) * (1/40MHz)



Note: Using the default CFG_PRBS_CHECK_PREDIVIDER setting of 0 (pre-divider

= 4) and CFG_PRBS_CHECK_MEAS_TIME setting of 3 (MEAS_TIME = 3), the TMT

(total measurement time) is ~77μs per measurement.

2. Follow the steps outlined in Figure 4-3: Timed PRBS Check Flow.

GS12281 Datasheet(PDF) 23 Page - Semtech Corporation

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