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Altera_Forum
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14 years ago

LVDS on GX transceiver error: "Impossible to choose a legal VCCIO value"

Hello, I am trying to use a Cyclone IV GX Transceiver as an input for LVDS signals. My target device is EP4CGX150CF23C7 and I am working with Quartus II 11.0 SP1 (Windows). When I assign "...
Altera_Forum's avatar
Altera_Forum
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14 years ago

It seems there is a workarround for the VCCIO bug. I opened a service request with Altera and this was their reply:

--- Quote Start ---

Sorry for my late response. I have perform some testing and found that this is a known software bug. It is schedule to be fixed in future Quartus release. Alternative, you can try it in older Quartus, 10.1 SP1, you will not see this issue. (...)

--- Quote End ---

So according to Altera this is a known software bug that should not exist in earlier versions. However, I did not try Quartus 10.1 SP1 as suggested. In the meantime, we had already converted our design to 1.5V-PCML for the GX Receiver inputs. Note that GX Transmitters are not able to output LVDS anyway.

Thanks for your replies, I hope this helps.