whitequark changed the topic of #glasgow to: glasgow debug tool · code https://github.com/GlasgowEmbedded/Glasgow · logs https://freenode.irclog.whitequark.org/glasgow
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<whitequark> hmmm, looks like i2c is broken on revC1
<whitequark> investigating why
<whitequark> (i2c in applets, not on the board itself)
<whitequark> oh
<whitequark> looks like the pull resistor on the A1 pin is broken
<whitequark> not sure how
<whitequark> we *really* need selftest for those huh
<whitequark> i... what
<whitequark> E: g.applet.internal.selftest: pins-pull: stuck low: A1 A3 A5 A7
<whitequark> how
<whitequark> wait. waaait
<whitequark> i'll be damned, half the level shifters on my revC1 flat out don't work
<whitequark> literally 75% of it is dead. 50% because the port B is broken, and 25% more because an entire row of shifters is dead
<hellsenberg> ouch
<sorear> any idea why?
<whitequark> not yet
<whitequark> hm, no, not ... quite? it seems more subtle
<whitequark> i'm not sure wtf is happening
<hellsenberg> weird that the half that failed is on the odd pins
<whitequark> ok, i think the shifters are actually fine and it was a bug in selftest
<whitequark> but yeah E: g.applet.internal.selftest: pins-pull: stuck low: A1 A3 A5 A7 B0 B1 B2 B3 B4 B5 B6 B7
<_whitenotifier-3> [GlasgowEmbedded/Glasgow] whitequark pushed 1 commit to master [+0/-0/±1] https://git.io/fjDGj
<_whitenotifier-3> [GlasgowEmbedded/Glasgow] whitequark bea50eb - applet.internal.selftest: add pins-pull test mode.
<whitequark> ok so why the fuck did this happen now...
<whitequark> hm
<whitequark> measuring the pull resistors with a multimeter, even ones are 10k ~exactly, odd ones are 9.2k
<whitequark> and the B-side ones are all 10k ~exactly
<whitequark> aaaaaaaaaaaargh
<whitequark> tnt: i figured out why the B-side doesn't work
<whitequark> because esden put the ESD diode package backwards :/
<whitequark> both of them are in the same orientation, but one of them should be a mirror image of the other no matter what else
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<whitequark> aaaaaand YEP this WILL short VIO to ground
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<whitequark> cuz it gets misaligned
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<whitequark> okay, so on the A-side, even pins have inf ohm to ground, and odd pins have 6k to ground
<whitequark> equivalently, 0.937V
<whitequark> ok, so from the shifter side of RN5, it's 1.007V, and from the pins side of RN5, it's 0.937V
<whitequark> to ground
<whitequark> therefore the fault is on the pins side
<whitequark> i've also excluded the shifter
<whitequark> er
<whitequark> the configurable pulls
<whitequark> that means the only thing that remains is the *other* ESD package.
<whitequark> wtf.
<whitequark> this fucking ESD thing is cursed
<whitequark> tnt: marcan: do your revC1s work correctly?
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<tnt> whitequark: yes, AFAICT. At least there is no shorts.
<marcan> whitequark: I have only one revC1, it seems to work fine so far
<marcan> haven't noticed any issues
<marcan> I haven't tested i2c though
<marcan> selftest passes etc
<sorear> equivalent series diabolicity
<tnt> the ESD are definitely not in the same orientation on my board (i.e. they look fine, one is rotated 180 compared to the other).
<marcan> whitequark: my ESD diodes are in the right orientation
<marcan> (opposite)
<marcan> looks like you got a seriously cursed unit :/
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<whitequark> aaaand failed rework...
<whitequark> oh hmmm
<tnt> can you just yank the ESD network out all together ?
<whitequark> yes
<whitequark> thats what i did
<tnt> and it didn't fix it ?
<whitequark> mhhhh looks like flux residue messing things up?
<whitequark> kay, i washed it in propane and acetone, that helped
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<whitequark> 'cept i still have another failure somewhere
<whitequark> on pin B3
<whitequark> ah i see.
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<whitequark> looks like this is a casualty of the reversed ESD package (?)
<whitequark> pin B3 behaves exactly like there is a weak pullup on it
<whitequark> with LDOs turned off, there is a resistance between B3 and GND that measures as about ... i'm not actually sure actually
<whitequark> let me just measure tRC with a scope
<whitequark> marcan: yeah, i think your idea of measuring tRC is actually really good
<whitequark> i thought the test is too sensitive as it is because it picks up e.g. wet flux residue... no. that is actually very very good
<whitequark> because it also picks up degraded silicon
<hellsenberg> O_o
<whitequark> i am 100% OK telling the fab to use a less shittier flux (or to do a solvent wash) in exchange for this capability
<_whitenotifier-3> [GlasgowEmbedded/Glasgow] whitequark pushed 2 commits to master [+0/-0/±2] https://git.io/fjDcR
<_whitenotifier-3> [GlasgowEmbedded/Glasgow] whitequark 5506af7 - applet.internal.selftest: fix stuck-high false positives.
<_whitenotifier-3> [GlasgowEmbedded/Glasgow] whitequark 0887474 - applet.internal.selftest: somewhat reduce false positives.
<whitequark> ... huh
<whitequark> it's not degraded
<whitequark> it's dead like the future of united kingdom
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<whitequark> i should decap it maybe
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<tnt> whitequark: you mean one of the io buffer ?
<whitequark> yes, the dead one
<whitequark> i wonder how exactly did it blow
<tnt> yeah, marcan tortured one to no avail AFAIR ...
<whitequark> indeed
<_whitenotifier-3> [GlasgowEmbedded/Glasgow] whitequark pushed 1 commit to master [+0/-0/±1] https://git.io/fjDCU
<_whitenotifier-3> [GlasgowEmbedded/Glasgow] whitequark 80773d8 - applet.sensor.bmp280: make --continuous output more readable.
<whitequark> ok, hm
<whitequark> other than the ESD issues i think everything that needed to be fixed for revC1 seems to work
<tnt> Well, backward soldering shouldn't be an issue wit PnP.
<whitequark> well no
<whitequark> there were two issues
<whitequark> one is a backward placed MG2040
<whitequark> and the other is *something else* that also traced back to an MG2040
<whitequark> that impacted A1A3A5A7
<whitequark> it was not soldered backwards...
<whitequark> seems like there was a short to ground
<whitequark> i should have x-rayed it i think, but i got impatient :/
<tnt> Oh, ok, I though only 1 side was bad.
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<pke> @tnt Depends on the packaging. Tubed parts can go 180 degrees. Also square parts can go 90 degrees over if the pickup is bad and vision corrects in the wrong direction. So yeah fab is hard. Also a board as complex as glasgow human visual inspection easily misses errors.
<pke> Does anybody know something about open source automated visual inspection? Newer seen an open solution before.
<tnt> pke: those are in reels.
<whitequark> pke: and they are not square. they are VERY much not square
<whitequark> the aspect ratio is like 1:4
<whitequark> as for human visual inspection... yes. unfortunately.
<tnt> if the gnd part weren't soldered/exposed at all, it wouldn't even have soldered 180deg appart, since it's not symmetrical.
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<pke> Sometimes at work i have to fix failed boards after testing and at the end of batch the cursed ones remain. Are cases when IC-s get placed upside down, legs in the air, and remain glued to the board because of the flux. From far seems fine. Until i check up-close and FCK.
<pke> My point is mistakes happen even if a robot does the job.
<tnt> Sure, but hopefully not 1 in 4 :p
<whitequark> well... i may have just been unlucky
<whitequark> 4 is a very small sample size to make any conclusions from
<tnt> Yeah sure, and glasgow is also not fun to assemble by hand, _lots_ of parts and bom lines :p I'm very thankful to esden to get one :)
<whitequark> indeed
<gruetzkopf> does unit 4 work?
<whitequark> . o O "unit-04"
<gruetzkopf> 2019-05-12T00:04 didn't happen :(
<whitequark> i'm confused
<whitequark> oh
<whitequark> oh shit
<whitequark> gruetzkopf: i think esden didn't make enough for that
<whitequark> but, i asked greg to make two more for some people
<gruetzkopf> yeah 4 is a bit too little for that
<whitequark> i think he might be fine making three? try dm'ing him on twitter
<electronic_eel> esden said he might make one for me to test the test jig, but he wasn't sure if he'll have the time for it
<tnt> somehow unit-04 meant something else to me :)
<whitequark> yes :p
<gruetzkopf> we're not doing S² powered glasgows anytime soon though?
<tnt> what could possibly go wrong
<whitequark> S2?
<whitequark> oh yeah
<electronic_eel> marcan picked the wrong silkscreen picture for that
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<sorear> mm 2-spheres
<electronic_eel> revNGE
* whitequark didn't even watch NGE
<whitequark> I keep meaning to...
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