whitequark[cis] changed the topic of #glasgow to: https://glasgow-embedded.org · digital interface explorer · https://www.crowdsupply.com/1bitsquared/glasgow · code https://github.com/GlasgowEmbedded/glasgow · logs https://libera.irclog.whitequark.org/glasgow · matrix #glasgow-interface-explorer:matrix.org · discord https://1bitsquared.com/pages/chat
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<whitequark[cis]> hm
<whitequark[cis]> when the bitstream is being loaded, both Dxn and Qxn are pulled high
<whitequark[cis]> unconditionally, by a pullup in the FPGA
<whitequark[cis]> this means that every pin becomes an output and outputs high
<whitequark[cis]> this is actually kind of bad
<whitequark[cis]> esden: it looks like we can avoid another BOM line by switching to 74AXP1T45 and swapping A-side and B-side
<whitequark[cis]> which also improves performance of the whole thing
<esden[m]> Just FYI I have 4000 of the existing design of boards right here... and I have enough of the 74 chips for ~2000? maybe 3000? boards here...
<whitequark[cis]> right
<whitequark[cis]> that's a lot
<esden[m]> Yes it is a lot of money too...
<_whitenotifier-6> [glasgow] whitequark opened issue #552: Reloading FPGA bitstream causes all outputs whose Vio is enabled to strongly drive high - https://github.com/GlasgowEmbedded/glasgow/issues/552
<esden[m]> So the PCB cost is ~$2000 to replace them with new ones. As for the level shifters, I will have to check the inventory to make sure how many I have, but it is roughly $2000 per 1k boards. So if memory serves I have about $4k-$6k worth of those parts here. All that data needs to be verified, this is of the top of my head.
<whitequark[cis]> I didn't realize you've ordered that many PCBs
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<Attie[m]> <whitequark[cis]> "this means that every pin..." <- I saw something like this recently, but didn't investigate... 🙈
<whitequark[cis]> it's been with us since revC0
<esden[m]> Yeah well... I ordered them recently as we had so many of the boards already in the field, and I need to fulfill the campaign and have inventory after. And it was a cutoff to get a decent price. It is more expensive to order smaller batches.
<whitequark[cis]> true
<esden[m]> They just got delivered _TODAY_ >_<
<whitequark[cis]> it's rather unfortunate that no one who noticed this behavior brought it up before today
<esden[m]> yeah...
<Attie[m]> (I only noticed if while playing with those Ethernet PHYs last week or whenever it was... recently though)
<esden[m]> I think the software mitigation solution should be implemented. As well as work on revC4 initiated. In the mean time I have no choice but to continue fulfilling the campaign though. I hope that the slowdown and downsides of the software fix won't be a show stopper for most use cases. When the revC4 hardware is implemented and tested we can evaluate what to do and how to switch over to that design.
<whitequark[cis]> sgtm
<Attie[m]> s/if/it/
<esden[m]> But let me say one other thing too. The pullup default mode on the ice40 is extremely dumb and annoying.
<whitequark[cis]> 100%
<Darius> what do you think of publishing an ECO if people want to mod theirs?
<Darius> eg tack on a pulldown
<Darius> I haven't looked at the PCB to see how horrible that would be though
<whitequark[cis]> infeasible
<Darius> bummer
<esden[m]> @darius that is a lot of pulldowns to bodge in 😬 ... and even more bodging to swap level shifters.
<Darius> yeah I was thinking it was only 1 pull down but of course not..
<whitequark[cis]> it's sixteen
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<q3k[cis]> Catherine: is that behaviour documented somewhere by lattice, or is this something you've only observed?
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<gatecat[m]> it's in the datasheet - "The default configuration of the I/O pins in a device prior to configuration is tri-stated with a weak pull-up to VCCIO"
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<alen6060[m]> If I want another glasgow I have to consider waiting for revC4?
<q3k[cis]> gatecat: 'tristated with a weak pull-up' uh-uh
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<galibert[m]> tristated but not really
<q3k[cis]> well that sucks (and not just for the glasgow usecase, it generally sounds like a terrible default state to be in)
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<gatecat[m]> it's definitely more normal for FPGAs (certainly ECP5, and I think Xilinx too) to have a weak pull-down by default
<gatecat[m]> although, iCE40 doesn't have pull-downs at all, so I guess it kind of makes sense
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<vegard_e[m]> default pulldown > default pullup > default floating
<whitequark[cis]> <alen6060[m]> "If I want another glasgow I have..." <- up to you; you might certainly have to wait for some time
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<_whitenotifier-6> [glasgow] wanda-phi opened pull request #553: applet.selftest: fix incorrect usage of `Pin.eq`. - https://github.com/GlasgowEmbedded/glasgow/pull/553
<_whitenotifier-6> [glasgow] github-merge-queue[bot] created branch gh-readonly-queue/main/pr-553-3e48dad25880587f2ec390b59177e1b773e29cec - https://github.com/GlasgowEmbedded/glasgow
<_whitenotifier-6> [GlasgowEmbedded/glasgow] github-merge-queue[bot] pushed 1 commit to main [+0/-0/±1] https://github.com/GlasgowEmbedded/glasgow/compare/3e48dad25880...9ef9d672584c
<_whitenotifier-5> [GlasgowEmbedded/glasgow] wanda-phi 9ef9d67 - applet.selftest: fix incorrect usage of `Pin.eq`.
<_whitenotifier-6> [glasgow] wanda-phi closed pull request #553: applet.selftest: fix incorrect usage of `Pin.eq`. - https://github.com/GlasgowEmbedded/glasgow/pull/553
<_whitenotifier-5> [glasgow] github-merge-queue[bot] deleted branch gh-readonly-queue/main/pr-553-3e48dad25880587f2ec390b59177e1b773e29cec - https://github.com/GlasgowEmbedded/glasgow