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Anonymous
Not applicable
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Anyone use 8B/10B encoder/decoder in GTH?

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Hello,

 

Can you explain why 8B/10B encoder or decoder in GTH are not used in example or default setting?

If I choose HDMI at video phy or GT wizard, the default setting does not use the embedded 8B/10B coding in GTH.

I also saw the xapp1275 example, it doesn't use GTH 8B/10B block.

I wondered why all the default setting and example do not use the block in GTH.

Do you know what's the reason?

 

Sincerely,

 

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nagabhar
Xilinx Employee
Xilinx Employee
7,316 Views
Registered: ‎05-07-2015

HI @Anonymous

It is just the All the HDMi and Display port encoding ,as per the spec, which will include 8b/10b encoding is done with in the respective cores  and Hence  the 8B/10B feature in the GTH transceivers is bypassed.

Hope this clarifies.

Thanks
Bharath
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austin
Scholar
Scholar
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Registered: ‎02-27-2008

g,

 

8B10B uses the channel less efficiently (10 bits used to send 8), so unless the application requires it, it will not be used.  Coincidence of what was chosen.  Generally, you design to meet a standard, so you do not have a choice.  Either its used, or no.

Austin Lesea
Principal Engineer
Xilinx San Jose
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nagabhar
Xilinx Employee
Xilinx Employee
4,122 Views
Registered: ‎05-07-2015

HI @Anonymous

 

HDMi subsystem+vidphy design do not use all the features in GTH transceivers like 8b10b encoding,
The necessary encoding as per HDMi standards is performed internal to the core and transceivers are used  merely to send out  or receive serialized  parallel data aprropriately

Thanks
Bharath
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Anonymous
Not applicable
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Thank you for replies.

 

I also knew HDMI subsystem and video phy do not use the embedded 8B/10B coding in transceiver.

But the reason is not still clear to me. The 8B/10B coding feature has existed long time. Even I can see it in 7 series. But if it is not still used, I wondered the reason is that the GT transceiver 8B/10B coding is not enough to support HDMI or Displayport or

just designers' preference.

 

Sincerely,

 

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nagabhar
Xilinx Employee
Xilinx Employee
7,317 Views
Registered: ‎05-07-2015

HI @Anonymous

It is just the All the HDMi and Display port encoding ,as per the spec, which will include 8b/10b encoding is done with in the respective cores  and Hence  the 8B/10B feature in the GTH transceivers is bypassed.

Hope this clarifies.

Thanks
Bharath
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athandr
Xilinx Employee
Xilinx Employee
4,101 Views
Registered: ‎07-31-2012
Either its the protocol that does not support it or the example design be default does not enable it or the default setting is the way it has been set to. Otherwise there is no restriction or limitation to use 8b/10b.
Thanks,
Anirudh

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Anonymous
Not applicable
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Thank you for clarification.

 

Now, I understood GTH 8B/10B coder is not for HDMI and DP.

HDMI or DP has its own 8B/10B coding method.

Th GTH 8B/10B implements a standard (general) 8B/10B coder, which can be used for Aurora.

 

Sincerely,