E-Tile Transceiver PHY User Guide

ID 683723
Date 9/30/2022
Public
Document Table of Contents

3.1.1.4. Data Pattern Generation

The data pattern generator is a Design for Test (DFT) feature capable of generating data traffic for the PHY to debug the PMA without involving the upper protocol stack layers.

The E-tile has an on-chip pseudo random pattern generation block that operates in all bit modes and can generate several patterns. In addition to this, it can generate an 80-bit user-defined pattern.

There are patterns supporting both NRZ and PAM4. Pseudo random bit sequence (PRBS) NRZ patterns are different from PAM4 patterns. Different specifications such as CEI OIF and IEEE 803.2, refer to quaternary PAM4 patterns differently. QPRBS13 is identical to PRBSQ13 and QPRBS31 is identical to PRBSQ31.

As defined in OIF Clause 16: CEI-56G-VSR-PAM4 Very Short Reach Interface specifications, typically, each cycle of PRBSQ13 is 8191 unique symbols long. Each cycle is formed by gray coding and PAM4 encoding of bits from two repetitions of the PRBS13 pattern and used for transmitter compliance testing.

Figure 50. QPRBS13-CEI Pattern

For more details on PRBS13Q pattern generation, refer to CEI-56G-VSR-PAM4 specifications. On similar lines, the PRBS31Q pattern is a repeating 231 -1 symbols long, formed by gray coding and PAM4 encoding of the PRBS31 pattern. This pattern is used for receiver testing.

Note: Gray encoding is enabled by default in PAM4 patterns.
Table 41.  Supported Programmable NRZ and PAM4 Patterns
NRZ Mode PAM4 Mode
PRBS7 PRBS7Q
PRBS9 PRBS9Q
PRBS11 PRBS11Q
PRBS13 PRBS13Q
PRBS15 PRBS15Q
PRBS23 PRBS23Q
PRBS31 PRBS31Q
User-defined 80-bit Pattern

More details on these patterns are as follows:

2 7 –1 PRBS pattern This standard PRBS pattern 11 is based on the generator polynomial x7 + x6 + 1 (refer to ITU V.29)

2 9 –1 PRBS pattern This PRBS pattern is based on the generator polynomial x9 + x5 + 1 (refer to CCITT O.151/ITU-T O.151)

2 11 –1 PRBS pattern This PRBS pattern is based on the generator polynomial x11 + x9 + 1 (refer to CCITT O.151/ITU-T O.151)

2 13 –1 PRBS pattern This PRBS pattern is based on the generator polynomial x13 + x12 + x2 + x + 1 (refer to CCITT O.151/ITU-T O.151)

2 15 –1 PRBS pattern This PRBS pattern 12 is based on the generator polynomial x15 + x14 + 1 (refer to CCITT O.151/ITU-T O.151)

2 23 –1 PRBS pattern This PRBS pattern 13is based on the generator polynomial x23 + x18 + 1 (refer to CCITT O.151/ITU-T O.151)

2 31 –1 PRBS pattern This PRBS pattern 14is based on the generator polynomial x31 + x28 + 1

For more details on Register Read/Write support and programming, refer to PMA Register Map and PMA Attribute Codes to configure these parameters.

11 This pattern repeats every 127 bits and you can use it with a PRBS receiver to facilitate loopback testing. This pattern facilitates the testing of chip-to-chip communications with other transceiver channel TX/RX Macro receivers on external chips or be fed to instruments such as a bit error rate tester (BERT).
12 This polynomial provides a data pattern that is more challenging for clock and data recovery circuits. Run lengths up to 15 1s or 14 0s in a row are embedded in the pattern. The pattern repeats every 215–1 bits (approximately 32.8 Kb).
13 This polynomial provides a data pattern that is more challenging for clock and data recovery circuits. Run lengths up to 23 1s or 22 0s in a row are embedded in the pattern. The pattern repeats every 223–1 bits (approximately 8.4 Mbits).
14 This polynomial generates data patterns whose run lengths are up to 31 1s or 30 0s in a row. The pattern repeats every 231–1 bits (approximately 2.15 Gbits).

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