DS160PR410EVM-SMA: schematic check

GARETH OU

Guru 11385 points

Part Number: DS160PR410EVM-SMA
Other Parts Discussed in Thread: DS160PR410

Tool/software:

DS160PR410EVM-SMA Evaluation Module (EVM) (Rev. B)

customer has a question. I see that the line requires a re-driver for both TX and RX.

customer oscilloscope measurement number can determine the EQ and Gain settings for TX.

How do we determine the EQ and Gain settings for RX?

Or should it be the same as the TX setup?

Thank you.

over 1 year ago

0 Nasser Mohammadi over 1 year ago

TI__Guru* 93670 points

Hi Gareth,

It is the same TX setup. DS160PR410 does not know whether the channel is used for either RX or TX. We can use scope measurement for both TX and RX.

Regards, Nasser

0 GARETH OU over 1 year ago in reply to Nasser Mohammadi

Guru 11385 points

Hi Nasser

Thank you for your explanation

The customer's oscilloscope can only power TX. Do you have any suggestions for RX?

0 Nasser Mohammadi over 1 year ago in reply to GARETH OU

TI__Guru* 93670 points

Hi Gareth,

Please send us a picture or block diagram of the setup so we can see your customer options to make this measurement.

Regards,Nasser

0 GARETH OU over 1 year ago in reply to Nasser Mohammadi

Guru 11385 points

Hi Nasser

As shown in the picture below, it is the same motherboard + base plate design. The re-driver will be placed on the base plate. Is there any recommended length of Y? If X=5”, Y=2”, what is the recommended gain and EQ adjustment for TX/RX respectively? Thank you

0 Nasser Mohammadi over 1 year ago in reply to GARETH OU

TI__Guru* 93670 points

Hi Gareth,

This depends on the insertion loss for X or Y. We should always start with EQ index of 0 and then increase one step at a time until we see eye diagram improving. As we increase EQ index, there will be a point where eye diagram gets degraded. At this point we should back off by or reduce EQ index by 2 steps.

Regards, Nasser

0 GARETH OU over 1 year ago in reply to Nasser Mohammadi

Guru 11385 points

Hi Nasser

How about RX if We can’t measure RX signal SI?

0 David (ASIC) Liu over 1 year ago in reply to GARETH OU

TI__Guru**** 176671 points

Hi Gareth

Due to the US Labor Day holiday, the response to your question may be delayed. We will look into your question when we return tomorrow, Sept 3rd. Sorry for the wait and any inconvenience it may cause.

Thanks,

David

0 Nasser Mohammadi over 1 year ago in reply to David (ASIC) Liu

TI__Guru* 93670 points

Hi Gareth,

A redriver can compensate for the signal loss on its input. There is not much it can do on its transmitter to make major changes on RX side of the CPU or end point. I think by RX you are referring to RX side of CPU or the end point.

Regards, Nasser

0 GARETH OU over 1 year ago in reply to Nasser Mohammadi

Guru 11385 points

Hi Nasser

Yes, I mean CPU PCIE_RX. How to adjust RX re-driver Gain and EQ? Thank you.

0 Nasser Mohammadi over 1 year ago in reply to GARETH OU

TI__Guru* 93670 points

Hi Gareth,

Please use DS160PR410 GUI. You can start with lowest EQ index and then increase one step at a time.

Regards, Nasser

0 GARETH OU over 1 year ago in reply to Nasser Mohammadi

Guru 11385 points

Hi Nasser

How to use the GUI? The GUI can check RX signal SI?

0 Evan Su over 1 year ago in reply to GARETH OU

TI__Mastermind 18830 points

Hi Gareth,

The GUI is used to change the redriver settings, typically this is best done through the Block Diagram panel of the High Level Page.

The GUI cannot check the signal quality anywhere, including on the CPU RX. To check the signal quality at the CPU RX, typically the CPU should be able to run specialized software that can perform lane margining on the PCIe link, Intel and AMD both have such tools for example. When this information is available, the redriver settings for that data direction can be tested and adjusted to find the combination that leads to the best results.

Best,

Evan Su

0 GARETH OU 11 months ago in reply to Evan Su

Guru 11385 points

Hi Evan

How do I use this gui?

0 Evan Su 11 months ago in reply to GARETH OU

TI__Mastermind 18830 points

Hi Gareth,

I would not recommend using the System page, it was originally meant for planning purposes but has been deprecated. Device register configuration can be performed in the High Level Page, which is where my screenshot was from.

Best,

Evan Su

0 GARETH OU 11 months ago in reply to Evan Su

Guru 11385 points

Hi Evan

After using this GUI, I still don’t know how to adjust the RX.

0 Lucas Wolter 11 months ago in reply to GARETH OU

TI__Mastermind 27700 points

Hi Gareth,

Does your CPU have a method to check the signal quality at its receiver? This is required to tune the redriver.

On the GUI, please use the Block Diagram Tab on the High Level Page. You can step through EQ indexes starting from 0, and clicking "Apply to All Channels" after each change. After each step, please check the signal quality at the CPU receiver to determine the best EQ setting.

Best,

Lucas

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DS160PR410EVM-SMA: schematic check