3rd Party/Other Boards and Kits

[thomas1974]

I have to enlarge a test board having FMC connectors with some more processing power in order to test some feature before going to layout. Therefore I want o transport data from one board to the other and strore it locally.

Basically I need to connect an FPGA (type to be defined) to possibly some DDR chips. A Spartan 6 will do from my investigations.

Which data rates could I expect in maximum using LVDS in between the two FPGAs? I expect a distance of e.g. 8-10 inches from pin to pin (over connector).

[eteam00]

• Is Spartan-6 also used for the test board?

• Are you asking how to connect two Spartan-6 devices -- through an FMC connector -- for maximum data rate?

• Are there limits which you have not yet described (e.g. number of pins or wires, logic swing, VCCO supply voltage, etc. etc.)?

-- Bob Elkind

[thomas1974]

1) Yes,

2) Yes

3) , Not so far-or let's say I have nothing to describe yet.

In detail I want to use another S6 for also the added board, so yes interconnecting two S6 will be the task.

I think I can use LVDS with direct interfacing using output/input termination in the two devices' io cells. Details about termination have to be found out.

The FMC connector seems to be properly routed, wereby length matching of the interconnections seems to be not too perfect, but ok.

The new question is, if parallel interconnection could probably succeeded by serial interconnection using SERDES.

What would you propose?

[eteam00]

Basically I need to connect an FPGA (type to be defined) to possibly some DDR chips.

Does the DDR (or DDR2 or DDR3?) affect the Spartan-6 to Spartan-6 links?

Which data rates could I expect in maximum using LVDS in between the two FPGAs?

Well...  the S-6 datasheet (DS162, Table 25) has useful guidance.  Roughly 1080 Mb/sec per LVDS pair, depending on speed grade.  How close to the datasheet performance guarantees do you want to get?

• Make sure you provide (in the custom-defined protocol) for re-calibration of the IDELAY2 blocks.
• Make sure you consult the VITA (FMC) spec on every possible design detail.
• Make sure you solicit design review advice from Ed McGettigan (user mcgett).
• You could use SP605 as a test platform, by wrapping FMC outputs back to FMC inputs.  I have not tried this, but it sounds like a plausibly good idea (so far).

-- Bob Elkind