E-Tile Transceiver " Reverse Parallel Loopback"

[HBhat2]

Hi,

I want to use " Reverse Parallel Loopback" feature for some protocol analyzer application.

I understood that in L-tile, Reverse serial loopback mode doesn't support for GXT (more than 17.6Gbps) speed.

In E-tile user guide, it is shown that reverse parallel loopback is supported. But no limitation is mentioned. With that, I can conclude that with E-tile, I can configure the transceivers in reverse parallel loopback @25Gbps also. 

Please let me know if any speed limitation with E-tile transceivers  for configuring in Reverse serial loopback mode.

With Regards,

HPB

[Deshi_Intel]

HI HPB,

This is an interesting question.

Let me consult Intel internal team further to see is there any data rate usage limitation for E-tile reverse loopback function.

Thanks.

Regards,

dlim

[Deshi_Intel]

HI HPB,

I consulted Intel internal team but so far we are not aware of any speed limit requirement on Etile reverse loopback path.

However, one important requirement in using reverse loopback path is (0ppm difference between the transmit and receive frequencies).

• You need to take care of ppm difference between your external test equipment and FPGA Etile refclk else data re-transmission from Etile Rx back to Tx path may fail

Thanks.

Regards,

dlim

[HBhat2]

Hi @Deshi_Intel ,

Thanks for checking internally & confirming that there is no speed limit for reverse serial loopback in E-tile Transceivers.

Can you provide some more details/document references on "(0ppm difference between the transmit and receive frequencies)"?

With Regards,

HPB

[Deshi_Intel]

HI HPB,

My understanding on the 0ppm difference is both FPGA Etile and external chip/test equipment need to share with same refclk source else it will induce ppm difference that may cause data loopback transfer failure.

Thanks.

Regards,

dlim

[Deshi_Intel]

HI HPB,

I hope I have clear your doubt on the ppm difference issue.

For now, I am setting this case to closure.

Thanks.

Regards,

dlim