Cyclone V HSMC Lvds differential pairs direction

Did you read the specification?

http://www.altera.com/literature/ds/hsmc_spec.pdf

When operated in LVDS mode, the signals are unidirectional, and hence the naming convention.

If you are making a custom system where you do not need to interface to any other HSMC boards, then you could re-define the HSMC LVDS TX lanes to be RX. However, if your system is custom, then just select a more appropriate connector solution. HSMC is not an industry "standard".

You might want to consider using FMC. FMC was a Xilinx idea, but at least its now a VITA standard (VITA 57).

http://www.vita.com/fmc

"FMC HPC connector provides connectivity for 160 single-ended or 80 differential user-defined signals"

The Arria V Development Kit has an FMC connector

http://www.altera.com/products/devkits/altera/kit-arria-v-gx.html

Cheers,

Dave

Thanks Dave!

When i went over the HSMC specs document I understood it was more general and not board specific. Unfortunately the board and HSMC connector has already been chosen so I was trying to get it to work with a custom system.

But if its true the HSMC LVDS TX differential lanes can be redefined so that i can use all 34 differential pairs as RX, then that will be perfect.

I will definitely consider using FMC in the next project.

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When i went over the HSMC specs document I understood it was more general and not board specific.

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The HSMC specification was something created by Altera, and only Altera use it. It is *board specific* in that boards that follow the specification should be compatible.

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But if its true the HSMC LVDS TX differential lanes can be redefined so that i can use all 34 differential pairs as RX, then that will be perfect.

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They cannot be re-defined if you want to call your board HSMC compliant. The specification *states* their direction. You could create a board that does not adhere to the specification, but then you would not call it an HSMC board :)

Bottom line is that you can use the Samtec HSMC connector however you see fit, but if you want to interface to other HSMC boards, then you must stick to the specification.

Cheers,

Dave