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gatecat / TrellisBoard

Ultimate ECP5 development board
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Consider 2 x 2 GB #1

Closed tommythorn closed 5 years ago

tommythorn commented 5 years ago

An ultimate board should IMhO maximize external memory. Since 2 GiB chips are only ~$13, qty 1, maybe you’d consider going to that?

daveshah1 commented 5 years ago

What is the source for these chips? I can't find any DDR3/DDR3L 16Gb x16 chips stocked by DigiKey. Going to two 8Gb chips for 2GiB total might be an option, but these seem to be about $26 each on DigiKey so not super cheap. I suspect most applications needing this much memory will be bottlenecked by the maximum clock frequency of the ECP5 anyway.

tommythorn commented 5 years ago

I have never used them so I can’t vouch for them, but https://www.components-center.com/product/Micron-Technology-Inc/MT41K1G16DGA-125-A.html

I strongly disagree with your assertion though. If you used this board for running Fedora/RISC-V, then 1 GB is very limiting. The argument I got from Fedora for why they wouldn’t support 32-bit RISC-V is that they have packages that can barely compile in 4 (or was it 2?) GB.

tommythorn commented 5 years ago

Aiee, the qty 1 was a misread, sorry. It’s qty 1020 but it doesn’t fundamentally change what I wrote.

daveshah1 commented 5 years ago

Seems like this part is now obsolete - https://media.digikey.com/pdf/PCNs/Micron/PCN-32255.pdf - so probably not a good idea to design it into something new. However, I will consider going up to at least 2GiB (two 8Gb chips) for the next revision as I can see this use case now (although compiling packages that need >1GiB RAM on a 100MHz system doesn't sound like a great deal of fun, adding swap into the equation won't help either)

tommythorn commented 5 years ago

Reasonable if you expect to produce more than 500 of these boards, but if they are pin compatible and just a part swap away, I’d personally just stock up and use them.