@jaseg@chaos.social
@jaseg@chaos.social avatar

jaseg

@jaseg@chaos.social

I am doing #electronics, #embedded programming, #python scripting, hardware security and recently some sewing. Pronouns: er/they

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whitequark, to random
@whitequark@mastodon.social avatar

@gsuberland if you light up a LED (cheap, recent green LED... InGaN or something probably?) and then turn it off by connecting both terminals to GND, how long does it take from that point to when it no longer emits appreciable amounts of light?

jaseg,
@jaseg@chaos.social avatar

@gsuberland @whitequark An effect you do have on top of the parasitics is the carrier lifetime of the LED junction. Carriers recombining is a stochastic process, and that leads to an exponential decay in brightness lasting several nanoseconds after turn-off.

jaseg,
@jaseg@chaos.social avatar

@gsuberland @whitequark Here's a neat appnote with tricks for modulating an LED fast: https://dammedia.osram.info/media/resource/hires/osram-dam-2496559/High-Speed%20Switching%20of%20IR-LEDs%20(Part%20I).pdf

rstacruz, to CSS
@rstacruz@hachyderm.io avatar

LOL - today I learned writing-mode: vertical-rl can flip form controls too 💀

https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_writing_modes/Vertical_controls

jaseg,
@jaseg@chaos.social avatar

@rstacruz It looks goofy with the rotated text here, but if you consider the way you'd place the field labels in vertical writing, it makes sense to rotate the controls, especially the long and thin ones like the drop down menu in the picture, or single-line text fields.

arturo182, to random
@arturo182@mastodon.social avatar

Look at those oscillator guard rings on the new Sparkfun board 👀

jaseg,
@jaseg@chaos.social avatar

@funkylab @arturo182 @davedarko I don't think you'll see any resonances in structures of that size close to an ~8 MHz crystal driven sinusoid-ish. I suspect they might help with the integrity of other nearby signals though, by providing a separate return path to the right place (the uC's ground pin) for inductively or capacitively coupled stuff.

attie, to random
@attie@chaos.social avatar

An STM32 NUCLEO board, with an onboard ST-Link... connected to st-util... connected to arm-none-eabi-gdb.

load - fine
cont - fine
^C - program appears to reset...

Is something going wrong for me, or should I be able to debug this in a normal way?

All sorts of other things appear to be behaving weirdly too. 😢

I'd really like to figure out why this firmware appears to be hanging while mounting a filesystem over 4-bit SD/MMC, but is fine with 1-bit...

jaseg,
@jaseg@chaos.social avatar

@attie Could it be a brown-out situation? I often have boards drop off SWD from unstable power rails.

jaseg, to Electronics
@jaseg@chaos.social avatar

RF transistor manufacturer CEL tells you in their datasheets not to lick their transistors.

https://www.cel.com/documents/datasheets/CE3512K2.pdf

jaseg,
@jaseg@chaos.social avatar

@akendo I want to know the story of the presumably very bored PhD student who decided to "chemically make gas or powder with [a CE3512K2 transistor]"

Qyriad, to random
@Qyriad@chaos.social avatar

I'm generally a fan of ${} for string interpolation in languages, just because it's easy to type, hard to miss, and rarely something you want to type literally in your strings

That is, unless you happen to be embedding bash scripts in your strings

The thing Nix does literally all the time

I feel like there was maybe a suboptimal choice here

jaseg,
@jaseg@chaos.social avatar

@Qyriad make has the exact same sub-optimal design choice in its makefile syntax.

whitequark, (edited ) to random
@whitequark@mastodon.social avatar

this is the most cursed serial PHY i've seen in years https://2384176.fs1.hubspotusercontent-na1.net/hubfs/2384176/MIPI-C-PHY-Introduction-From-Basic-to-Implementation.pdf

chaotic evil PAM3 without doing PAM3

jaseg,
@jaseg@chaos.social avatar

@whitequark lol, this is less PAM-3 and more like three phase LVDS in a "three phase alternating current" sense. Next up: three phase ethernet with braided triplets instead of twisted pairs using three phase pulse transformers 😆

foone, to random
@foone@digipres.club avatar

the raspberry pi pico is a neat and cheap microcontroller but I just hate the SDK for it.
every time I've tried to write any code for one I've spent 95% of my time trying to get the fucker to build properly and only 5% actually writing code

jaseg,
@jaseg@chaos.social avatar

@azonenberg @whitequark @foone I have that feeling whenever I have to use an ESP-32 for anything. Their toolchains are so cobbled together. I once rewrote their serial bootloader tool because I was tired of wrangling raw memory adresses on the command line instead of just using elf files.

ja2ke, to random
@ja2ke@idlethumbs.social avatar

This video from Corridor Crew is pretty amazing. They re-create the nearly perfect compositing from the penguin dance sequence in Mary Poppins, which was achieved using high intensity sodium vapor lights and a very custom beam splitter, instead of a blue or green screen. It truly feels like a lost art rediscovered. When the matted footage just perfectly drops in I gasped haha https://m.youtube.com/watch?v=UQuIVsNzqDk

jaseg,
@jaseg@chaos.social avatar

@rberger @ja2ke That might work. The reason you want a narrow spectral peak in the first place is that you want the background to be about the same brightness as the foreground so it doesn't swamp out the color image, but you want to concentrate as much of that yellow light energy as possible inside of the matte image filter's passband while keeping that filter as narrow as possible because making the filter wider will mess up the color image.

jaseg,
@jaseg@chaos.social avatar

@rberger @ja2ke LEDs have a substantially larger bandwidth than a sodium vapor lamp, but if they are too broadband depends on how narrowband their filters in the video are. You're right in that you definitely want a straight yellow/red/whatever LED instead of a phosphor-converted one, as the PC ones have much broader bandwidth, and usually have a peak of the original blue or purple showing through as well.

jaseg,
@jaseg@chaos.social avatar

@rberger @ja2ke btw, if you want a "single frequency LEDs" with much narrower bandwidth, a diode laser is essentially that. You pay with both cost and efficiency though. Also, a laser puts out light that is both narrowband and coherent, and if you don't care about the coherence, it can be a nuisance since it causes speckles from interference when you illuminate an area with laser light.

jaseg,
@jaseg@chaos.social avatar

@gunstick @rberger @ja2ke Yes, there are some techniques. Most of them involve mechanically moving or vibrating some optical component such as a diffuser. To me, they seem too complex compared to buying a couple low-pressure sodium bulbs.

gsuberland, to random
@gsuberland@chaos.social avatar

am I the only one completely uninvested in raspberry pi stuff? there always seems to be some fervour about their newest unobtainium SBC doodad and I never quite understand the use-case for the price.

jaseg, (edited )
@jaseg@chaos.social avatar

@gsuberland the weird thing to me is that you can get a used laptop with several times the performance, built-in battery, keyboard, mouse and screen and more I/O options for about the same price as a pi plus necessary components like a quality microSD card and a chonky USB power supply.

jacqueline, to random
@jacqueline@chaos.social avatar

the good shit has arrived

jaseg,
@jaseg@chaos.social avatar

@jacqueline Looking at the datasheet for that solder made me notice that I never really understood the tradeoff in silver content in SAC lead-free solder, so I did a little bit of research.

In case anyone is interested, I found a really nice paper that goes into detail on shock performance, temperature stress performance, wetting characteristics and more. Here's a link:

https://smtnet.com/library/files/upload/Effect%20of%20silver%20in%20common%20leadfree%20alloyspaperEng042309.pdf

jaseg,
@jaseg@chaos.social avatar

The Tl;dr is that more silver means a lot better mechanical strength, slightly worse shock strength, and better wetting of the joint. High-Ag (>=3%) alloys can produce deformed joints during cooling because of a "platelet formation" process, which requres precise T control during automated reflow soldering. Small amounts of Bismuth make the joint look nicer.

chipperdoodles, to random
@chipperdoodles@chaos.social avatar

any recs for hosting my design source code for chippydootles? I currently am on gitlab because it's just something I knew of but it's performance is just horrendous on low end devices. not a huge problem if you're just grabbing one link to clone but definitely just dumb

jaseg,
@jaseg@chaos.social avatar

@chipperdoodles For my repos, I use github b/c everybody has that, but all of them are also mirrored on my own cgit/gitolite instance at https://git.jaseg.de/

This way I don't have to maintain something as complex and security holey like gitlab, and I make it easy for people to find my stuff and contribute to it. If github goes down tomorrow, nothing of value is lost this way.

ross, to random
@ross@fosstodon.org avatar

The Verge article on the best printer in 2024 is just completely brilliant in so many ways.

And also kinda sad.

https://www.theverge.com/2024/4/2/24117976/best-printer-2024-home-use-office-use-labels-school-homework

jaseg,
@jaseg@chaos.social avatar

@ross They're on point. I bought one of those brother cheapies for less than 100€ recently, and it's working great. Apparently they have been churning out my exact model for at least ten years now. It doesn't have wifi, has no cloud integration, doesn't even have a display, but just works without a fuss, and does an adequate job.

jaseg,
@jaseg@chaos.social avatar

@TheLancashireman The epson ink tank ones have a really weird DRM racket on its waste ink sponges though. Like, you can refill the ink tanks just fine, but Epson charges you something like $50 for replacing the $1 waste ink sponge after a couple years and put some bullshit in their firmware to enforce that limit.

janamarie, to random
@janamarie@chaos.social avatar

Thanks for specifying the package loss??

jaseg,
@jaseg@chaos.social avatar

@gregly @janamarie They didn't so much do that as they just explicitly list the (inevitable) loss rate that is intrinsic to any parcel post service. Even fedex had a handful of plane crashes that presumably destroyed whatever parcels were on those planes. I think these rates useful knowledge for a customer, especially shopping from a far away place.

It's similar in spirit to how over here in Europe, online retailer galaxus lists the return rates for electronic devices that they sell a lot of.

arturo182, to random
@arturo182@mastodon.social avatar

has now officially announced the multi-color silkscreen service.

I've had access to it for about a week and have been working on a @kicad plugin. It almost kinda works now 😁

jaseg,
@jaseg@chaos.social avatar

@arturo182 Did they end up removing the weird DRM encryption stuff from it, or is that still in?

jaseg,
@jaseg@chaos.social avatar

@arturo182 That's good to know. I think I'm going to add support for it to gerbonara without the DRM bits then.

Nixie, to random
@Nixie@nixie.name avatar

Ever seen an encoder and thought: "Damn, that looks pretty af!"

Dual encoder, I'll save it for later. Now I'm hunting for a detentless 24ppr encoder PEC12R-4017F-N0024

So far I have only found it on Digikey and I have either to pay 18€ or buy 50€ of stuff...

jaseg,
@jaseg@chaos.social avatar

@Nixie LCSC has a similar part available for less than 10$: https://www.lcsc.com/product-detail/Rotary-Encoders_ALPSALPINE-EC11EBB24C03_C470790.html

They also have a bunch of these funky hollow-shaft ALPS ones that are like 25mm in diameter. The ALPS EC30 series is large enough to fit a standard cherry MX keyswitch in the middle 😆

bitluni, to random
@bitluni@chaos.social avatar

What could be more enjoable on a sunny day in Santa Monica than sitting down for a coffee with @sprite_tm and hacking an vintage panel from Apex

image/jpeg

jaseg,
@jaseg@chaos.social avatar

@attie @mntmn @bitluni I wonder if given their form factor, you could maybe emulate onne with a small oled or tft and a color filter.

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