azonenberg changed the topic of #scopehal to: libscopehal, libscopeprotocols, and glscopeclient development and testing | https://github.com/azonenberg/scopehal-apps | Logs: https://libera.irclog.whitequark.org/scopehal
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<azonenberg> Seems there is demand for solder-in probes
<azonenberg> but... yeeeah
<azonenberg> that probably works at uart speeds at least :p
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<balrog> azonenberg: I'd say depends on how clean the signals are :p
<azonenberg> that extension looks like at least ~8 inches
<azonenberg> call that about a 2.25 ns round trip delay for the reflection
<azonenberg> So you should see a quarter wave null from that stub at ~440 MHz
<azonenberg> and significant attenuation at much lower freqs
<azonenberg> as well as a giant step in all of your remotely fast edges
<azonenberg> low tens of mbps might be ok as long as the edges are slow
<azonenberg> fast spi you would almost certainly get double clocking
<_whitenotifier-e> [scopehal] azonenberg pushed 1 commit to master [+0/-0/±3] https://github.com/azonenberg/scopehal/compare/6bf1fe98c70d...4d2fa38b8d7e
<_whitenotifier-e> [scopehal] azonenberg 4d2fa38 - IBISDriverFilter: now handle propagation delay of buffers properly. Fixes #557.
<_whitenotifier-e> [scopehal] azonenberg closed issue #557: IBISDriverFilter: better handling of high latency output buffers - https://github.com/azonenberg/scopehal/issues/557
<balrog> azonenberg: how good are the older HP/Agilent/Keysight/similar woven cables meant for logic analyzers that you can find on eBay?
<azonenberg> no idea, never done any testing on them
<azonenberg> Also, speaking of cables
<azonenberg> the cables I ordered for AKL-PT5 testing came in
<azonenberg> working with the vendor to get the file share set up so i can get the actual serialized .s2p's they provide
<tnt> balrog: AFAIK those are distributed resistance cable a bit like the scope probe cables.
<azonenberg> Cost almost nothing extra to have the vendor serialize and characterize the cables. To 26.5 GHz no less
<azonenberg> The loss is quite a bit less than the sum of the minicircuits and SV cables I had been using before
<azonenberg> and it's more flexible
<azonenberg> and it costs less than the SV cable alone
<azonenberg> so cheaper, no need to connect two cables together, more flexible than the minicircuits one, fully characterized
<azonenberg> seems like a winner on every front
<azonenberg> The s-param data they provided shows them being very consistent too
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<azonenberg> in terms of both amplitude and phase match. even though i didnt pay extra for phase matching
<azonenberg> they're like 3 degrees apart at 25 GHz
<azonenberg> not trivial, but not bad at all for something i didn't specifically ask for matching on
<Degi> Two cables together?
<Degi> How would you even do phase matching on a cable, besides changing the dielectric?
<azonenberg> adjusting the length presumably
<azonenberg> or more likely, making a bunch and picking the closest ones
<azonenberg> usually when you want matching you only want two specific cables matched wrt each other and dont care as much about absolute phase/length
<azonenberg> since it's typically for a differential signaling application
<Degi> I wish differential cables were more popular, as in scientific ones, I guess a SATA cable would work.
<d1b2> <zyp> SATA cables are annoying in that they aren't crossed; if you connect one between two identical boards you end up wiring TX to TX and RX to RX
<d1b2> <zyp> i.e. drives have to have TX and RX reversed wrt. the motherboard/host
<d1b2> <TiltMeSenpai> wut
<d1b2> <TiltMeSenpai> that's... cursed
<d1b2> <zyp> well, it's reasonable enough when there's two distinct roles and it'll only ever be used between one of each kind
<d1b2> <zyp> I mean, HDMI cables aren't crossed either, you'd have the same problem there
<azonenberg> yeah i had to deal with that on my sniffer board
<azonenberg> i have explicit sata host/device ports
<d1b2> <zyp> what makes the SATA stuff extra fun is that the quad SAS cables are crossed, so there's one kind of breakout cable from that to four SATA connectors for connecting four SATA drives to a fancy HBA
<d1b2> <zyp> and then there's a reverse breakout cable looking exactly the same, but used to connect four regular SATA host ports to a SAS backplane
<d1b2> <zyp> I know this because one of my friends managed to buy the wrong kind recently :p
<azonenberg> yeah i encountered that years ago with a Norco 4U chassis
<d1b2> <zyp> I think that's what he got too, IIRC it got 20 drive slots and he wanted to run the last four off the motherboard SATA controller
<azonenberg> yep
<azonenberg> similar story
<balrog> I've seen USB 3.0 cables used for that stuff...
<balrog> usuall A-B
<balrog> usually*
<d1b2> <zyp> there's the A-A cables all those pcie risers are using, I assume those are crossed
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