Virtex® Family FPGAs

[simboyar_com1022]

Hi All!

Do Virtex 6 GTP transceivers have direct access inside GTP IP core?

I plan to transmit repetitive sequence of bits with High bit rate, i.e. 2.5 Gbps or 3.125 Gbps without GTP transceiver IP core adds extra data to sequence. I mean that TX side of transceiver does not add idle, comma or any other clock synchronization character to transmitted bit stream.

[mcgett]

The data that you provide to the TXDATA port will be the data transmitted. 

[barriet]

I believe the previous reply meant to include "when the 8b/10b encoder is bypassed - see ug366.pdf for the full details, including TXENC8B10BUSE usage."

Also, there is no GTP on V6 - it is a GTX (or GTH available on HXT parts).

bt

[barriet]

I know that no additional characters are added by the encoder even when not bypassed- just meant to clarify that technically TXDATA is only transmitted exactly when the encoder is not used. Otherwise the 8b/10b  process occurs.

bt

[mcgett]

The original poster asked about inserting of  "comma or any other clock synchronization character" to the transmitted data stream.  

Encoding doesn't add anything to the data stream, it is just a transformation of the 10bits that you give (TXDATA[7:0], TXCHARISK, TXCHARDISPMODE) each cycle into a different set of data bits.  The 8B part of the 8B10B is a bit of a misnomer.

[barriet]

Understood... .;)

I just didn't want someone else to read this (without the benefit of a detailed reading of the transceiver guide) to assume that TXDATA was always what was being actually transmitted. Even though the encoder operates at a character/byte level and still doesn't actually add additional primitives - just transmits a suitably transformed version of the user's transmit data.

bt

[simboyar_com1022]

As a clarification, In case I bypass 8/10 encoder and provide repetitive TX data with appropriate rates. Does transceiver guaranty constant timing between sequences?

Thank you all.

[mcgett]

> Does transceiver guaranty constant timing between sequences?

The MGT will just transmit what you give it.  Why do you think that it would do something else?