C6457 SERDES Loopback test

Brian Bell

Other Parts Discussed in Thread: TMS320C6457

What are the proper steps/settings required to run a SERDES loopback test?

Background:
This is a new custom board design that's in bring up / debug.
SERDES communication with GbE PHY is not working.
Therefore, ran loopback tests with the following results:
EMAC Loopback test - successful.
SGMII Loopback test - successful.
SERDES Loopback test - FAILS

MDIO communication with PHY works.

Thanks,
Brian

over 13 years ago

0 Bryan Busacco over 13 years ago

Expert 1215 points

Here is additional information on this topic.

It appears that we are setting something in the DSP incorrectly because we also tested our C6457 EVM with the same results as our own board.

We have successfully run the loopback test work for the EMAC and SGMII. When advacnein on to a loopback test for SWERDES, it fails.

What are common pitfalls that we may be missing in getting this test to work properly?

We are referencing the SPRUGK9.PDF, TMS320C6457 DSP Ethernet Media Access Controller (EMAC)/ Management Data Input/Output (MDIO) User's Guide.

Thank you,

0 Bryan Busacco over 13 years ago in reply to Bryan Busacco

Expert 1215 points

Can someone help by making a suggestion?

Thanks,

Bryan Busacco

0 Asmit Patel over 13 years ago in reply to Bryan Busacco

Prodigy 120 points

Hi Bryan,

Have you tried with the code available with McSDK? Try that first with EVM, if it works, then just compare your code with McSDK code.

0 Chad Courtney over 13 years ago in reply to Asmit Patel

TI__Mastermind 30825 points

I'll 2nd the comment by Asmit, please try the MCSDK and let us know how that goes. I suspect it's a configuration related issue.

Best Regards,

Chad

0 tscheck over 13 years ago in reply to Chad Courtney

TI__Mastermind 23525 points

The loopback you are talking about is TX to RX loopback right? Not RX to TX, which the Serdes never support...

I'm not 100% sure that TX to RX Serdes Loopback is actually being supported, but this is what you'd have to do...

Besides the Loopback bits (19:18) being set to 2b01in the Aux_Cfg register, you have to set the ENTEST bit in the TX_CFG and RX_CFG register. The ENTEST bit is labeled RESERVED in the SPRUGK9, but it is bit 1 of both of these registers.

Regards,

Travis

0 Bryan Busacco over 13 years ago in reply to tscheck

Expert 1215 points

Hi, the ENTEST reserved bits may turn out to be the problem ... however, how do we determine if the Tx to Rx is indeed supported on the C6457?

Thanks,

Bryan Busacco

0 tscheck over 13 years ago in reply to Bryan Busacco

TI__Mastermind 23525 points

Just to be clear, the SerDes supports it fine, it should not be an issue. Please let me know what you find.

Regards,

Travis

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C6457 SERDES Loopback test