azonenberg changed the topic of #scopehal to: libscopehal, libscopeprotocols, and glscopeclient development and testing |,, | Logs:
<azonenberg> First attempt at eye patterns on USB with clock gating by bus activity and fast PLL re-sync to the preamble
<azonenberg> as you can probably see results are... suboptimal :p
<whitequark> hah
<whitequark> hm, i should make floppy eye diagrams, for fun
<whitequark> i guess it wouldn't really work, it'd just be like slapping a copy of my histogram at the top
<azonenberg> i dont know what the signal coming off the read-write head looks like
<whitequark> i can probably do some surgery on my floppy drive?
<whitequark> wait that sounds medical
<whitequark> hm, i wonder if it's possible to realign the drive heads
<whitequark> shit
<whitequark> ok done
<azonenberg> lolol
<azonenberg> did you bork it?
<whitequark> azonenberg: yes, screwed up head alignment
<whitequark> and then fixed it
<whitequark> just by looking at graphs and using my demodulator
<whitequark> i think people typically had to use special equipment for that but i used my fingers and brain instead :D
<whitequark> azonenberg: anyway. there is a testpoint conspicuously labeled "PREAMP" on the board.
<azonenberg> lol
<azonenberg> So you can get the raw signal off?
<azonenberg> What's it look like?
<whitequark> azonenberg: can you grab data off my scope now?
<whitequark> ch1 ac 20mv/div
<whitequark> ch4 has demodulated data
<whitequark> er
<whitequark> amplified
<azonenberg> Looking, h/o
<azonenberg> Can't connect
<whitequark> azonenberg: retry
<whitequark> 5 us/div btw
<azonenberg> Connecting...
<azonenberg> Hmmmm
<azonenberg> What's the range on CH1?
<azonenberg> I show it as about -100 to +50 mV and it's disappearing off the top of the plot
<azonenberg> Did i get the sign of the offset term wrong?
<whitequark> no
<azonenberg> oh wait it looks good now
<whitequark> i moved it :D
<azonenberg> gotta restart the app, i commented out the "flush cache to read settings from scope" thing
<azonenberg> We need to figure out how to handle that
<azonenberg> you can either have a timer that triggers a lag spike every so often (longer = less laggy but slower UI updates)
<azonenberg> or require an explicit "refresh settings from scope" command
<azonenberg> This will of course not be an issue in my scope, because i'll have the ability to send push notifications via the management channel and not step on the data socket...
<whitequark> yeah
<azonenberg> Also yeah it's working, i'm just getting one waveform per ~30 sec or so
<azonenberg> yay for high latency low-bandwidth WAN links :p
<azonenberg> It's still really cool being able to pull data off test equipment in russia from my desk off the coast of seattle though
<whitequark> haha yes
<whitequark> so, can i take my hand off the probes now?:D
<azonenberg> yeah i've seen a bit of the waveforms
<azonenberg> go do your thing, i have some billable work to do
<azonenberg> The rigol driver is at minimum viable read-only level right now, btw, if you want to play with it a bunch
<whitequark> no i mean my fingers are cramped from holding 2 probes wth one hand and typing with the other
<azonenberg> But all of the set functions are gone
<azonenberg> are empty*
<azonenberg> also, you need to get some proper probe holders
<whitequark> true
<azonenberg> Did you see the ones i had in my photo yesterday?
<whitequark> nope, missed that
<azonenberg> The board at left is the inline usb probe
<azonenberg> the tiny thing i'm probing is an FT232RQ, mini USB, and 4-pin 100 mil header
<azonenberg> (one of my first experiments in miniaturization, three boards cost <1 USD at oshpark shipped)
<azonenberg> Then the black stick is my homebrewed probe with a custom 3d printed enclosure made to fit the Pico probe holder
<azonenberg> Pico sells them for their own probes, but they work with most common passive scope probes including the ones that come with my lecroys
<azonenberg> And i'm designing my own to fit them
<azonenberg> They have rubber feet and the body isn't solid plastic, there's some kind of metal core inside it to give it some mass
<azonenberg> So they don't move around easily
<azonenberg> They're 25 USD each which seems quite reasonable compared to the $100+ ones from lecroy that do the exact same thing
<whitequark> huh
<azonenberg> You could probably 3d print something equivalent and just glue a ~10mm steel rod into each leg and put a rubber foot over it
<azonenberg> But IMO the time+materials would be >$25
<azonenberg> also lol keysight's N2786A is literally the exact same thing but costs $66
<azonenberg> People have also hacked up something similar with a pair of wooden clothespins, although they don't have the weight of the proper probe holders and would likely be much more sensitive to vibration
<azonenberg> Pico TA102 is the part number I use
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<_whitenotifier-3> [scopehal-apps] azonenberg opened issue #42: Figure out how/when to flush cache and load configuration from scope -
<_whitenotifier-3> [scopehal-apps] azonenberg labeled issue #42: Figure out how/when to flush cache and load configuration from scope -
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