<ldcd>
afaik that feature isn't excercised in revABC and seems a likely spot for timings to be different
<ldcd>
but also i have no plans on sending cypress money for an FX2 so not attempting to support the non clone on revd feels like a sensible call
<whitequark>
it is not exercised in revABC, but configuring the GPIF peripheral doesn't break anything
<ldcd>
oh yeah
<whitequark>
WAVEDATA is just RAM
<whitequark>
and EP2GPIFFLGSEL doesn't do anything unless you start a GPIF transaction
<whitequark>
i also tested things on revABC
<ldcd>
thats not my concern there, just that if someone did put an FX2 on a revd it might not work as is
<whitequark>
we are going to try that
<ldcd>
ah ok
<ldcd>
sg
<whitequark>
the GPIF configuration interface should be OK, i think
<whitequark>
but you are right
<whitequark>
may have to add wait stats
<whitequark>
*states
<whitequark>
which is thankfully very easy with GPIF
<ldcd>
yeah
<ldcd>
it seems like the corebai chip is probably on a newer process
<whitequark>
yes
<ldcd>
and therefore probably has less cursed shit going on
<whitequark>
significantly more modern
<whitequark>
i'd guess 40nm because 3V3-native
<whitequark>
maybe 65?
<whitequark>
hard to see it being 22
<ldcd>
65-40 sounds reasonable
<whitequark>
should get one to Andrew to decap
<whitequark>
actually, one thing i was gonna make is some HF
<ldcd>
i can also do that
<whitequark>
should be easy: get some fluorite, boil down some H2SO4, a+b=hf
<ldcd>
you don't need HF in your life
<whitequark>
i used to have HF in my life
<ldcd>
was your life better then?
<whitequark>
then i moved to the UK and for obvious reasons did not bring it with me
<whitequark>
hahaha, touché
<whitequark>
it was really not
<ldcd>
i'll grab one next time i make an LCSC order
<ldcd>
which might be a while
<whitequark>
thank you
<whitequark>
i have two loose ones here
<whitequark>
i can just send you an envelope
<ldcd>
sg
<ldcd>
QFN or BGA?
<whitequark>
QFN
<ldcd>
nice
<whitequark>
don't think the FX2 ever came in BGA
<ldcd>
ok that should be straightforward
<whitequark>
you got a choice of QFN and incredibly massive QFP with like 120 pins
<ldcd>
i thought i saw a BGA on the corebai chip?
<whitequark>
hm
<whitequark>
oh maybe corebai did that
<whitequark>
we're using the fully FX2-compatible package
<whitequark>
QFN56
<whitequark>
i'm very impressed with corebai because as best as i'm able to test this is a complete and indistinguishable functional replacement in terms of logic behavior
<ldcd>
yeah looks like they did
<whitequark>
glasgow exercises quite a few features of the chip too
<ldcd>
i mean idk if it is actually produced
<whitequark>
i was worried the GPIF would be broken somehow. nope, works
<ldcd>
yeah its quite impressive
<ldcd>
thats part of why i want to decap
<whitequark>
it's also way cheaper which makes it more impressive
<whitequark>
clearly quite a bit of R&D went into it
<ldcd>
i'm also wondering if some stuff is microcoded so they could fix stuff with a patch or metalspin
<whitequark>
and it can't be a high volume product from the mail we exchanged earlier
<whitequark>
i'm wondering what the bonus RAM does
<ldcd>
yeah
<ldcd>
poke it and see if any peripheral shits the bed
<whitequark>
lemme read it a few times in a row at first
<ldcd>
has the old FX2 been decaped before?
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<duskwuff0[m]>
you can still get cheap "develope board" [sic] for the FX2 pretty easily on eBay et al
<duskwuff0[m]>
they're easiest to find by searching by the part number, CY7C68013A
<josHua[m]1>
FX5/FX10/FX20 are ludicrously expensive. I cannot believe how much they are asking for it. I've used it for prototype but for any kind of production it like doubles the BOM of anything else
<josHua[m]1>
the FX20 on this board is almost more expensive than the gigantic FPGA sitting next to it
<whitequark>
that is true
<whitequark>
if we had a toolchain for it we could use a Zynq on Glasgow
<whitequark>
iirc that has USB3?
<whitequark>
it definitely has USB2 at least
<whitequark>
oh i guess 7-series has 2 and US+ has USB3
<josHua[m]1>
it is really nice to have it as an interface to this FPGA, and it has been very reliable once I got it to actually work, to use Gen2x2 to get five cameras worth of data into my Mac Studio
<whitequark>
yep
<whitequark>
there are reasons besides not having a reasonable package that we're not using FX3G2
<whitequark>
part of it is the effort of supporting two firmwares at this specific moment
<whitequark>
but part of it is cost! the corebai chip is like... 4 times less expensive I think?
<josHua[m]1>
(I wonder if I can convince the client to open source the LiteX IP that I wrote to sync and speak to FX20.)
<josHua[m]1>
how much is the Corebai part?
<whitequark>
16.5 RMB in 2024
<josHua[m]1>
oh that is not many RMB
<whitequark>
exactly
<whitequark>
it's not quite free but it's not far from it
<whitequark>
on par with adding a connector or two to the BOM
<whitequark>
i think the RAM chips we have on revD are 3.5 times more expensive (each)
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<whitequark>
should find some CN vendor who sells OctoSPI devices
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<whitequark>
the pull circuit on revD0 doesn't seem to work right... wonder why
<josHua[m]1>
by interesting comparison, Trion T8 is 15 kbyte of block RAM and is ~$4 qty1.5k; T13 is 90 kbyte is more like $9; and then you still need to add a NV boot flash
<whitequark>
does T8 have USB?
<josHua[m]1>
I guess you would also probably want to glue on an ULPI PHY
<whitequark>
and then you need an entire USB stack, and a way to put a gold bitstream in the NVM, and make sure it never gets erased...
<josHua[m]1>
right
<whitequark>
i really like FX2 because it's unbrickable. you will never, ever, end up needing to flash your debug tool
<whitequark>
any competing solution has to be at least that good
<whitequark>
NVM with hardware WP# and gold bitstream in top half could work
<josHua[m]1>
they can twin-boot from flash, as long as you can protect it
<whitequark>
yes, they usually can
<whitequark>
then you also need to be very confident your USB stack is good
<whitequark>
and i try not to be responsible for an entire USB stack RTL because it's kind of a minor nightmare
<josHua[m]1>
right
<whitequark>
especially if hubs are involved
<whitequark>
it is definitely an option! but it's an option I'm avoiding very hard
<josHua[m]1>
yeah, I mean, this is not to say that it woudl be the easiest option, or even a good option. and it is still more expensive than the Corebai!
<josHua[m]1>
but it is getting closer to the point that it is possible these days
<whitequark>
also with Corebai, you order 2.5K and then wait 6-8 weeks, so I think they manufacture them on demand?
<josHua[m]1>
oh that's scary.
<whitequark>
I mean there are stocks at LCSC and so on
<josHua[m]1>
if the Corebai had not come along, and we were still at the whim of Cypress, a PLD-based FX2 analogue would have been a much more compelling option
<whitequark>
yes
<whitequark>
I think I could probably design a part where the basic USB bootloader is very robust and easy to audit
<whitequark>
and then you can bootstrap up from that to anything else meaning you don't need the rest to be perfect
<whitequark>
i.e. what the FX2 has basically
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<whitequark>
i think i am capable of writing RTL that parses one setup packet, stashes the result into some sort of NVM, then boots into it
<whitequark>
one type of setup packet i mean
<josHua[m]1>
right. I mean, valentyusb seems pretty well field-proven at this point
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<whitequark>
I'd probably want to use LUNA to keep the codebase manageable, but yes it's an option to use an existing stack as a black box in gold RTL
<ldcd0[m]>
the other thing that makes me think the 2g3 is just a 5 is that if they actually wanted to sell them in quantity they'd probably also adjust the metal so it can be bonded into a QFN
<ldcd0[m]>
if they're already spinning new masks for everything
<whitequark>
point
<ldcd0[m]>
LGA makes me think they're just taking their FX5 they designed for BGA and ordering a slightly cheaper LGA package
<ldcd0[m]>
but also the whole thing seems like a mess so maybe they are just making bad decisions for no reason