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Altera_Forum
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9 years ago

Illegal I/O standard

Hi, When I compile my design I end up in the following error: Error (169092): Illegal I/O standard 3.3 V Schmitt Trigger for pin <SCL> -- I/O standard not supported by output pins in target d...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
9 years ago

Hi,

according to the MAX 10 device datasheet, Schmitt trigger inputs are supported on all pins ("max 10 devices support schmitt trigger input on all i/o pins", see section "dc characteristics").

I think the problem is that you are trying to select Schmitt trigger characteristics for an output pin. A Schmitt trigger only makes sense for inputs.

I don't know though how this behaves when your pin is bidirectional. "SCL" sounds like an I2C clock pin; if you want to support clock stretching, that pin would have to be bidirectional ("inout" in VHDL). I would expect that you can configure such a pin as Schmitt trigger.

Best regards,

GooGooCluster