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Altera_Forum's avatar
Altera_Forum
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14 years ago

Yes No question (Using FPGA as a wire)

1-Can I use FPGA, just as a wire, to carry a bidirectional line like I2C SDA from one pin of the FPGA to the other pin of the FPGA. In the FPGA there will not be an i2c master or slave it will just r...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

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Unfortunately, I have to contradict. All existing physical level I2C repeaters or level converters are based on special hardware features, please review the respective datasheets. A similar function can't be implemented with regular FPGA IOs as far as I understand.

A repeater on a logical protocol level would be possible, but not an easy design.

P.S.:

That's exactly the point.

--- Quote End ---

And I have to admit, I was a bit quick. Using cross-connected opendrain IO would create a lock-up loop, i.e. when one of the two SDA is pulled low, the other will be pulled low as well, in its turn pulling ... you see what I mean.

Like you say a protocol solution will be elaborate. But with a dedicated Master Port on one side and a dedicated Slave Port on the other side it may reasonable feasible, because then the direction of the buffers will be predictable. Still a bit of work, though.