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Bluebirttoday at 9:30 AM3 repliesview on HN

Neat project - there are already a couple of good open FPGA projects. Have a look at Dirk Koch's and the FABolous teams work. They are doing exceptional work.

But all open FPGA projects miss the IO required for a good design. They do not have any serdes hardware nor DDR IO cells.


Replies

LarsKrimitoday at 10:07 AM

This project seems to have a serdes block which seems to wrap whatever is in the PDK. Didn't look too far down but from a cursory glance it looked like it was built for an internal clock of 50 MHz (clock default to 20 ns) with an oversampling of 8: 400 MHz

If those numbers are at all right it puts it in useful territory. Very much so for a first spin

For a first spin it looks overall pretty useful. The only nitpick I have would be that `operation` on the DSP tile should be from fabric instead of config (hardcoded in bitstream) otherwise I don't see a convenient way of resetting the accumulator(?)

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rosscomputerguytoday at 2:51 PM

Yeah, I did see there's been attempts but none really satisfied what I wanted out of it. I do know of FABulous and it seems good but not quite what I wanted. You can see that aside from yosys and nextpnr, it is quite self contained and even provides a very easy way of defining new silicon with Nix.

I know that IO is really the 2nd thing which sells FPGA's. I did design a basic serdes hardware that should just work for this first generation. I do want to do DDR IO cells in the future.

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__patchbit__today at 9:41 AM

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