Andrew Zonenberg

Security and open source at the hardware/software interface. Embedded sec @ IOActive. Lead dev of ngscopeclient/libscopehal. GHz probe designer. Open source networking hardware. "So others may live"

Toots searchable on tootfinder.

ngscopeclient: https://www.ngscopeclient.org/
Blog: https://serd.es
Location: Seattle area
GitHub: https://github.com/azonenberg

Public Key

npub1wpgh8qdt8suzxy8f2luspksj4wpdfw53weq4v8dr7llqp3t72tds3rf386

NIP-05 Address

[email protected]

Profile Code

nprofile1qqs8q5tnsx4ncwprzr5407gqmgf2hqk5h2ghvs2krk3l0lsqc4l99kcpz3mhxue69uhhyetvv9ujuerpd46hxtnfduqs6amnwvaz7tmwdaejumr0ds306xct

Publishing to

relay.damus.io

nos.lol

Author Public Key

npub1wpgh8qdt8suzxy8f2luspksj4wpdfw53weq4v8dr7llqp3t72tds3rf386

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Last Notes

2026-03-28 01:07:13 CET

Zombie: "Braaaaains"
Fedi user: "Traaaaaains"

2026-03-26 14:59:33 CET

The existence of toblerone implies the existence of related triangular hydrochocolate chains such as the base alkane (toblerane), as well as the closed ring form (cyclotoblerone)

2026-03-21 18:11:18 CET

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it took my wife a long time to train me not to wear shoes around the house. My childhood home had enough legos and random junk on the floor that if you went barefoot around the house it would rapidly prove a painful mistake.
I used to keep my shoes next to the bed when sleeping and pretty much only take them off to sleep or shower

2026-03-19 16:52:59 CET

Every time I post a bunch about crazy inner layer rework I get a couple of reactions from people who think that being this good at bodging boards makes me some kind of EE god.
Nothing could be further from the truth.
You know how you get this good at fixing board design errors? Yeah, exactly how you'd think. Making a lot of them :P

2026-03-19 16:43:35 CET

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What's the return loss of the kitty?

2026-03-09 19:16:27 CET

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every time I hear "hugging face" I think of xenomorphs and no slop company propaganda will ever change that

2026-03-06 23:58:15 CET

Wrote up the blog-format version of the TCXO failure analysis including a bit more backstory and commentary all in one place
https://serd.es/2026/03/06/TCXO-failure-analysis.html

2026-02-26 05:50:26 CET

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Chat can i retire early?
https://files.ioc.exchange/iocexchange/media_attachments/files/116/135/123/879/205/359/original/82d77dc60068e2a6.jpg

2026-02-26 05:37:51 CET

VM server going down for the third attempt at updating to xcp-ng 8.3 after two previous failures resulted in rollbacks and changes to my SR configuration to hopefully be compatible with 8.3.
Also doing the first of two rounds of hardware upgrades after I scored a bunch of nice stuff from some servers that were headed to the scrapyard.

2026-02-21 01:02:39 CET

Anybody have a non emergency service contact for Puget Sound Energy? They have a contact to report outages and downed wires but not lower priority issues.
We've pretty definitively figured out what's going on at my friends' place: intermittent brownouts on one of the two 120V phases affecting the entire house but not neighbors. Waveforms show glitches in the sine right above and below the zero crossing consistent with series arcing. And it happens more often in windy weather.
All of the evidence points to one crimp on the secondary side of the transformer going bad. Just a matter of figuring out how to get a lineman out on the pole to replace it.

2026-02-16 19:36:43 CET

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the whole circuit is switched by a single 120V SPST switch controlling all four bulbs wired in parallel. There is to my knowledge no other switch.
And the capacitors are inside the LED bulbs as part of the SMPS circuit.

2026-02-16 19:20:51 CET

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all four bulbs are in parallel and the other 3 turn off fine. It's definitely discharging stored energy in a capacitor

2026-02-16 18:39:55 CET

Someone please explain this to me
https://files.ioc.exchange/iocexchange/media_attachments/files/116/081/524/037/393/749/original/17aaa77ee52cb062.mp4

2026-02-11 21:55:35 CET

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E2EE for open groups is pointless, an adversary can just join your group and see everything. No cryptanalysis and no hacking required.
For small closed groups, use signal.
The niche we need to fill is large public group chats with a better UX than IRC.

2026-02-11 21:54:43 CET

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What I want to see is basically IRC + formatting fixes, reply chains, and image embedding for group chats, plus strong binding of user accounts to signal accounts and a nice UX for clicking on a user in a group chat and jumping into a signal DM with them

2026-01-27 02:58:34 CET

Steps to greatly advance the state of the art in any relatively obscure field:
1) Find a bunch of autistic nerds whose special interests broadly overlap with said field
2) Put them in contact and let them share ideas or, better yet, lab space
3) Buy them whatever they ask for
4) Wait and see what they come up with. Excitement guaranteed, you just have no idea exactly what kind.

2026-01-01 21:28:42 CET

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Has any state made serious efforts towards outlawing the data broker industry outright?
As in, rather than forcing individual residents to opt out of data collection, mandate that as soon as you become aware someone is a California resident they implicitly treat that as a deletion request.
And banning the operation of data brokers within state lines (even if not handling CA resident data) including employing CA residents, selling data to CA companies, etc.

2025-12-27 06:52:30 CET

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If you want Good BNCs, get Rosenberger.
They'll cost a fortune, but they have this incredibly smooth feel to them - snug, but no burrs or binding or sticking. Some of them are rated to 10 GHz which is just ludicrous for a BNC. Insertion and return loss performance are excellent.

2025-12-25 00:06:02 CET

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the cockroaches will be IRCing over HF radio after whatever apocalypse wipes out humanity.
It's the messenger that will outlive all others. Like cockroaches it's not pretty but also nearly impossible to kill.

2025-12-10 23:51:29 CET

Random thought: the centralization of authentication to a few big OAuth providers like MS and Google, combined with services that time out your cookies and force relogins every so often, makes phishing people so much easier.
Want someone's account creds? Just pop up something that looks like a ms or google login form, odds are they're so conditioned by login fatigue that they'll automatically type their creds and TOTP token into it.

2025-12-05 17:33:45 CET

Seeing all of the Flock posts lately got me wondering: is there a privacy-preserving way to accomplish the public benefit of traffic/speed cameras (reducing speeding and red light running) without also turning them into blanket ALPR spies tracking where everyone goes?
The best idea I came up with is a split system architecture that treats the camera as adversarial.

2025-11-24 09:33:21 CET

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After a while it didn't even make sense or refer to any of the stories at all.
(long list of European kings)
B: "King Henry the 8th"
M: "King Henry the 9th"
(we ran out of Europeans and switched to the Zulu)
B: Shaka
M: Dingane
(list went on until we couldn't remember any more)
Eventually the ritual would end and we'd actually have a real conversation about which to play.
Is this a normal kid thing or just a neurospicy version? Lol.

2025-11-24 09:30:58 CET

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M: "Well, I don't see why not. What type?"
B: "Well, I don't see why not. What type?"
M: (chanting) "Pooper-scooper kitty 1945" (this had started out as "super kitty 1945")
B: "No-no-no-no-no-no-no-no-no" (he was tired of it because it was my favorite for a long time)
My memory gets fuzzy but we went on for several minutes like this suggesting various ideas and being shot down.

2025-11-24 09:29:00 CET

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Towards the end it went something like this:
Brother: "Your Majesty, wilt thou express thy intentions to do a P. if there are any. Or, if there are not any, wilt thou express thy intentions to turn into a hippopotamus and fly away?"
Me: (chanting) "Could we turn into a hippopotamus and fly away?"
(pause)
M: "Could we do a Puh?"
B: "Duh"
M: "Sku"
B: "Sting"
M: (chanting) "Could we do a Puh-Duh-Sku-Sting?"
B: (chanting) "Could we do a Puh-Duh-Sku-Sting?"

2025-11-24 09:26:23 CET

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But before we could do any of these, we had to agree on which one to play that night.
This became a very long, involved ritual that was constantly having new verses added.

2025-11-24 09:25:13 CET

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Another involved "super kitty", a cat on a Pacific island in late WW2 trying to fend off a Japanese invasion, I think with the aid of other cats?
And then there was the KWSTG ("killer whale and sea turtle game") involving me as the sea turtle and my brother as his orca friend adventuring in the ocean.

2025-11-24 09:24:08 CET

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There were a bunch of different storylines that continued for years in parallel. Nearly all involved intelligent animals, but closer to Redwall / Watership Down style (i.e. human level intelligence but physically unchanged) rather than anthro type.
The original, which became the namesake for them all, involved prairie dogs or "P.D." (pronounced "puh duh" or just "puh" for short). I forget most of the details of that one.

2025-11-24 09:21:28 CET

When I was probably 12ish and the older of my younger brothers was around 10, we all shared a bedroom with me on the top bunk and both of them on the bottom (it was a twin + double stack meant to sleep 3).
If we weren't ready to sleep yet, we'd pass the time with D&D-esque verbal roleplaying games (no dice or anything, story flow purely driven by him as the DM and remaining characters).

2025-11-10 19:18:01 CET

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You don't even need tape, big hard drives are cheap and you can hook them up to the cheapest i3 motherboard on the market if you just need to use it for backup storage over the internet.
My offsite backup is six of the largest cost-effective hard drives (4TB at the time I set it up) at a friend's house; we have a "poor man's colo" arrangement hosting offsite backups for each other and peering over OpenVPN.
Large spinning rust is not *quite* as dense as tape, but more than good enough for 99% of users.

2025-11-04 03:34:23 CET

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you can also buy individual sleeves (although sold in pairs they're not physically connected)
https://www.northernsafety.com/Product/16751/Honeywell-North-Silver-Shield-20-Chemical-Resistant-Sleeves-Pair

2025-10-22 20:35:18 CEST

Does anyone have (freely available non-NDA encumbered, i.e. reverse engineered) area figures for ARM Cortex-A processors, ideally on TSMC 28nm?
Even rough single data points would be helpful.
I have some Zynq-7s (28HPL dual A9) in my microscope food bin, but it seems like nobody's published an xc7z substrate die shot yet and it might be a while before I get to mine.

2025-09-30 18:16:01 CEST

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I'm amazed more people don't understand that having your entire economy dependent on an expensive commodity with highly volatile pricing, that's primarily produced by countries hostile to your interests, which are always fighting each other, is a significant national security risk.

2025-09-28 17:42:51 CEST

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Except that most AI GPUs have no video output.
Most of them can probably be repurposed for scientific computing purposes, although they may not perform great at that (I'm not sure about the ratio of float32 to float64 to neural network performance in e.g. one of the big Blackwells compared to a current generation workstation/HPC GPU).
For anything that needs video output, they're useless.
I am starting to look into multi-GPU for ngscopeclient to see how practical using a headless GPU (or just one other than the one your display is plugged into) for all the number crunching, then copying the final rasterized waveform textures to the display GPU for final video output.

2025-09-21 18:18:14 CEST

Internet hive mind: what are these?
Options I'm considering are cellular microcells, water/power meter collectors (my leading candidate), some kind of public wifi network.
Guesstimating 900 MHz band from the antenna size as best i can guess from ground level, but I don't have a SDR on me to be sure.
https://files.ioc.exchange/media_attachments/files/115/243/178/802/003/341/original/90e0b6e745ef85a2.jpg

2025-09-11 18:07:30 CEST

The ngscopeclient team is excited to announce our first official release, version 0.1, after many years of development.
This release includes contributions from 77 people across the globe and supports instruments from 23 vendors, running on all major operating systems.
https://www.ngscopeclient.org/news/2025-09-11-v0p1-release.html

2025-09-11 02:44:18 CEST

Periodic reminder to new followers or anyone just swinging by: I have high speed digital design / SI experience and lots of nice lab toys. Most folks can't afford this kind of stuff so I try to share the love.
If your project is open source or generally noncommercial / hobby in nature, there's NO CHARGE for a quick design review or some basic lab measurements. If you send me a board for characterization and want it back, all I ask is that you send me a prepaid label or reimburse my return shipping costs.
If it's a major time commitment for me or you plan to make money from the project, I might still be interested but we'd have to discuss compensation. As a general rule I don't want to price people away; I use the day job and occasional industry-rate projects to subsidize the cost of offering steeply discounted services to folks who can't afford to pay industry rates at a "real" lab.
Capabilities include but are not limited to:
* Schematic/layout review
* 3D planar EM simulation (Sonnet)
* Oscilloscope measurements to 16 GHz
* BERT measurements to 25 Gbps NRZ
* VNA measurements to 8.5 GHz
* Metallographic cross section sawing, embedding, and polishing
* Wet chem for IC decapsulation, metallographic etching, etc
* Optical microscopy to ~300nm resolution including automated large-area scans
* UV/VIS/NIR spectroscopy
EDIT: almost forgot to add, advanced PCB rework capabilities including inner layer circuit edits and bodgewires down to 125 um and micro 100 ohm twinax for differential pair bodging

2025-09-05 05:59:17 CEST

Design review thread. I'm going to be looking at https://git.sr.ht/~mxsparks/ceres-hardware/ by @npub1lxl…pjmr from mostly a SI/PI viewpoint.
This board has already been fabbed (https://xgdr.net/2025/08/15/ceres-revA-bringup/) so I'm not going to be spending much time worrying about looking for pinout or basic "does it boot" issues.

2025-09-04 16:48:17 CEST

The existence of perjury implies the existence of juries in lower oxidation states

2025-09-04 12:03:35 CEST

Not enough developers understand the responsibilities of having a large userbase and how important preserving freedom of users is.
Every time you change the way something works, the cost of that change is borne by your entire userbase. If you have a million users and you move a button and everyone spends 30 seconds figuring out where it went, that's 8333 hours of wasted effort. At $150/hr for a somewhat average tech salary, you've cost your userbase $1.25M with that one change.
Sometimes breaking changes are unavoidable, but the more fundamental the change and the more extensive the retraining users need, the more cautious you need to be about doing it.
It's not just about your "creative expression" or some manager's vision of "the right" way to do things. If you can possibly add a preference to keep a workflow the way it does, add it.
Even today in ngscopeclient it hurts me every time I make a change that breaks a workflow. I rationalize it as "better now than later, while the userbase is small", and we're still very much in "experimental" stage in the v0.x series. But I do it fully understanding that I'm throwing a lot of people off every time I merge a dialog into something else, etc.
I don't know how many users we have since we have no analytics or telemetry, but it's enough that I'm sure every small change I make turns into thousands of dollars of wasted time at minimum.

2025-09-02 04:14:48 CEST

Kcmil has to be one of the most cursed units for area.
If you're not familiar with North American wire sizes, heavy gauge wire like power lines are often sized in kcmil (sometimes abbreviated MCM because M = roman numeral 1000, not SI "mega").
As in kilo circular mils, where a circular mil is the area of an 0.001 inch diameter circle.
Not even *square* mils. Circular mils. Because irrational units and conversion factors for area are the best

2025-08-27 11:06:07 CEST

Hmmm.
I should probably do something about this section in the documentation before we ship v0.1, right?
https://files.ioc.exchange/media_attachments/files/115/099/925/309/606/664/original/87e53f2f00beb7b0.png

2025-08-24 18:34:37 CEST

Anybody else feel like they're working the lunch counter at Subway whenever they put on sunscreen?
Especially the Coppertone that comes in the bottles that squeeze out the bottom like the Subway condiment bottles.
"Ok sir... what else on this? Black olives, Parmesan cheese..."
"And two squirts of SPF 50"

2025-08-20 07:38:24 CEST

IC reverse engineering software is absolute crack for neurospicy brains.
Every time I'm on a project for work where I get to use it, I have to force myself to put it down when I'm supposed to be done with work for the day. You can probably tell how that's working out given that it's 2230 local time.
It's the most addictive puzzle game out there by a massive margin. There's the "fix stitch errors" mini-game, the "fine tune inter layer alignment" mini game, the "optimize feature extraction" mini game, dozens to hundreds of "what is this standard cell" mini games, and then the main "wtf does this giant netlist do" storyline.
If only it wasn't dongle-locked, export-restricted software sold at EDA-tool seat prices...

2025-08-19 20:59:19 CEST

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Name and shame. If not the actual company, the recruiter for not having the sense to throw the startup under the bus for being dangerously stupid.

2025-08-15 09:25:06 CEST

For all the marketing advice LinkedIn MBAs come up with, a surprising number of people forget one of the most basic steps: The Middle Schooler Test.
The process is simple:
1) Place a sample of your brochure, website, etc. in front of a recently calibrated 12-year-old boy.
2) If they start giggling uncontrollably, identify and correct the source of their amusement. Return to step 1.
3) If they aren't particularly amused, move on with the campaign.
https://files.ioc.exchange/media_attachments/files/115/031/572/687/523/103/original/12808be52ec59c9b.jpg

2025-08-11 13:22:00 CEST

Anybody else think "HBCU" sounds more like a bank than a place to get an education?

2025-07-30 21:10:00 CEST

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Last time I checked old.reddit.com was free from such idiocy.

2025-07-30 21:09:23 CEST

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i only go there in a browser *in a virtual machine that I don't use for anything but social media*.
Keep it locked up in a padded cell where it can't do anything I don't want it to.

2025-07-25 01:13:47 CEST

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Yep.
Keep radio links for mobile deployments where you actually need the flexibility and can tolerate poor performance since the alternative is no connectivity whatsoever.
Using any kind of wireless link for a fixed site is just dumb.

2025-07-24 02:01:33 CEST

Is anyone aware of publications or research on what sort of bugs LLM-generated or LLM-assisted code tends to have?
Like, we have a huge body of knowledge in the security community about how to audit human-generated codebases for the types of bugs that human developers commonly write.
But we don't have that kind of data yet (AFAIK) for the vibe-coded monstrosities all of us are going to be pentesting soon.
Gut feelings:
* There are some common threads and patterns of errors, but they're very different from purely human-authored code
* There's a lot of subtle bugs where code looks good at a glance, but is missing some knowledge of interface behavior in another module or component that was outside the context window or something
Assumptions:
* We don't know exactly which lines in the subject codebase were written by humans and which by stochastic parrots
* The code at least appears to function correctly for a nontrivial fraction of inputs, i.e. it compiles and has been debugged sufficiently that a customer is considering shipping it

2025-07-15 22:36:28 CEST

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How do you continue growing when the majority of the world's population already uses your products? Magically inventing more customers (at least, faster than the birth date) is not going to happen.

2025-07-15 06:53:15 CEST

Why does milk say "homogenized" and not "homoogenized"?

2025-07-10 07:50:08 CEST

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The limited flash on the H750 should mostly be a non issue. My typical firmwares so far are barely over 128 kB all told, and I have a ton of executable RAM to work with.
So I can put a minimal bootloader and BSP (and maybe firmware update SFTP server) in the internal flash, bring up the FPGA, then copy my application image from spare space on the FPGA config flash to SRAM and jump to it.
The only other issue is that I normally run microkvs in the last few flash sectors. So in a single-sector flash part, I can't do that. Instead, I'd need to add a memory mapped interface to the FPGA-attached flash and store my config there. (I could also attach an extra QSPI flash to the MCU but that adds BOM cost, it's more pins to route, and most importantly involves dealing with the cursed OCTOSPI peripheral).
It'd take a bit of coding to get all of this done, but I think it's worth the effort. I may still go with the 753 for new designs long term but since I have 750s on the shelf, might as well use them up for one-off / low volume projects.
The larger BGA ball pitch alone is enough of a reason.

2025-07-10 07:44:11 CEST

Starting to look more seriously into the STM32H750/753.
The 753 is the part I really want to use, the 750 is the same die fused down to disable all but the first 128 kB of flash. But I picked up several of them during the chip shorage and I feel like I should put them to use.
They're mostly comparable to the H735 I use now. Key differences:
* CPU Fmax down from 550 to 480 MHz
* RAM nearly doubled from 564 to 1024 kB
* Flash increased from 1 MB to 2 MB in the 753, but reduced to 128 kB in the 750
* 40 more GPIOs (128 -> 168)
* Package enlarged from 201 ball 0.65mm (10x10 mm) to 265 ball 0.8mm (14x14 mm).
That last bit is what has me the most interested. The 0.65mm H735 package is usable on OSHPark 4L, barely, but you lose a lot of IO and the parallel memory controller etc. aren't practical to use.
While the H75x is available in the same footprint, you can also get it in the 0.8mm package which should be much more friendly to the large via sizes offered on OSHPark. So it could be a winner for prototypes where I care more about ease of access to IO and MCU-FPGA interfacing than about absolute max CPU performance.

2025-07-05 22:18:42 CEST

I just described bus timetables at a local transit center as "leading / lagging the ferry phase" in order to "provide sufficient setup/hold margin" for transfers between modes of transit.
Does that make me some kind of nerd?
It seriously is a synchronous CDC between, dare I say, buses.

2025-06-29 21:34:15 CEST

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last time my blog was on the front page of HN my server was using 1% of 1 vCPU and like 128 MB of RAM.
And had a load average of like 0.01.

2025-06-25 17:52:17 CEST

Just opened my github dashboard and saw a copilot slop search bar.
Anybody have a ublock rule to get rid of this?

2025-06-22 23:53:04 CEST

The recent European switch to attached bottle lids for recycling is very interesting to me, because as an American I've always been told that plastic bottle caps *cannot* be recycled, and should be thrown in the trash while only the bottle itself gets recycled.
Anybody know the origin for this? Was it just a desire to sell more single-use plastics? Are detached lids so small that the effort to extract them from the waste stream is too much to justify the amount of material you get? Something else?

2025-06-21 08:25:53 CEST

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No, I want to do it live on a board not for debugging.
The use case is to have device A polling an I2C sensor, and MCU B passively listening for the traffic and making a note of the readings.

2025-06-21 07:40:34 CEST

Is there such a thing as a microcontroller with "I2C promiscuous mode"?
In other words, I want to passively snoop bus traffic and be alerted when e.g. somebody talks to address 0x90, but not actually ACK it myself.

2025-06-20 05:20:48 CEST

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I figured upstreaming would either blow up in my face or get me a really good relationship with them.
My mental calculus was that they're a tiny company (like two dozen people or so), I'm a very happy customer showing off their product all the time on my birdsite (at the time), and paying them several thousand dollars a year in support contract fees on top of the... probably around $20K? initial outlay for the seat over the years of upgrades.
And I'm offering to nearly double the speed of their product and not even asking for anything in return.
While they would be legally within their rights to sue me for breach of contract, actually doing so would be monumentally stupid.
So I decided to take the risk and tell them about it.

2025-06-20 05:16:25 CEST

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"... so check your email, I've sent you an authorization on company letterhead to keep it up as long as you maintain an active support contract."
A few months later when I was visiting friends and family on the east coast, I stopped by their offices, only about a 2-hour drive from RPI where I was visiting some former classmates who had settled in the area.
Had pizza with the VP of ops I had spoken to before, their VP of engineering, my support engineer, spent several hours discussing everything from proposing improvements to the material library (having detailed Dk/Df data for specific cores and prepregs vs just an average for a given material) to looking over source code and discussing more optimization potential.
Later on I got an NDA for partial source code access, cleaned up my patch more, and upstreamed it. It just released in v19 a few weeks ago.
https://files.ioc.exchange/media_attachments/files/114/713/507/181/187/764/original/d6a32a211d36ee81.jpg
https://files.ioc.exchange/media_attachments/files/114/713/507/195/726/177/original/c6680b1d644efcd7.jpg

2025-06-20 05:12:00 CEST

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He said he looked me up on linkedin and as soon as he saw I went to RPI (where he did his undergrad a few years before me) he knew what was going on.
Then went on to say "Sooo we've talked to our lawyers, and they say we can't have people going around breaking our EULA willy-nilly. You do realize what you did was against the terms of our license, right?"

2025-06-20 05:10:40 CEST

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After a couple days of crickets from my usually very responsive support engineer, I got an email asking me to join a call with a VP.
I figured this was gonna be really good or really bad.

2025-06-20 05:09:38 CEST

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I literally got fed up with how slow the solver was, threw it in VTune and IDA, rewrote the inner loop of their matrix solver in assembly, patched it into the binary, verified I got the same results, and got a 40-70% speedup depending on workload.
Then I sent them a "pull request".

2025-06-20 05:07:53 CEST

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See the line about AVX in the log file?
Yeah. That was me.
https://files.ioc.exchange/media_attachments/files/114/713/483/091/862/180/original/c43f1575d2b851dd.png

2025-06-20 05:05:01 CEST

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Yeah.
I mean, I'm not paying MSRP though... You've heard about how I ended up getting a good deal right?

2025-06-20 04:59:38 CEST

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Feedlines for the simulator, they're de-embedded but have to be present to make the ports work out.
Tl;dr you get weird results if you try to make a port that doesn't have ground on an adjacent layer to use as a reference. This is fine if you have a reference plane but if you're voiding the plane, adding a short feedline seems to usually be the easiest way to work around it.

2025-06-20 04:52:11 CEST

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Yep.
This is the host-side launch for the connector that will be going from the FPGA board to the two line cards (two connectors, total twelve 5 Gbps NRZ lanes, per line card) as well as to the front panel dual SFP28 carrier (one connector, total four 25 Gbps NRZ lanes).

2025-06-20 04:46:28 CEST

I'm pretty happy with the top side Samtec ARF6 launch simulations now.
S11:
* Red: No cutout, -12 dB at 10 GHz, -7 at 20 GHz, -4.8 at 30 GHz
* Blue: Rectangular ground cutout the size of the pad, -22.5 at 10 GHz, -16.4 at 20 GHz, -11.7 at 30 GHz
* Green: 30um larger than the pad on all sides (1.06 x 0.41 mm), -30.5 at 10 GHz, -22 at 20, -15 at 30.
With the oversized cutout it's more than good enough for QSGMII and 25Gbase-R.
TDR:
* Red: No cutout, 64Ω Zdiff at the launch
* Yellow: Pad-sized cutout, 86Ω
* Orange: Oversized cutout, 94Ω
https://files.ioc.exchange/media_attachments/files/114/713/376/257/555/739/original/18c72022fb02e82e.png
https://files.ioc.exchange/media_attachments/files/114/713/376/258/161/715/original/0f513ae3c1805337.png
https://files.ioc.exchange/media_attachments/files/114/713/376/266/111/330/original/747b3a5849f8255d.png
https://files.ioc.exchange/media_attachments/files/114/713/376/299/981/941/original/7a38235cc9150e43.png

2025-06-19 21:34:23 CEST

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Relative positioning for groups of windows under the same application is probably good enough.
But as of now, there's no way AFAIK to do things like
* Determine the position of one application window relative to another
* Restore a saved window layout
* Spawn a new window at the cursor location
* Drag an application-managed (not window manager controlled) toolbar etc. out of the application and spawn a new top level window
* Drag a window-manager controlled window into the application and dock it as a toolbar
xdg-toplevel-drag looks like it has potential for some but not all of these use cases.

2025-06-19 20:51:33 CEST

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so yes, if and when wayland achieves feature parity with X i might switch.
But right now they seem to be explicitly saying "we will not implement these features". There are multiple tools I use that are either going to be impossible to port to wayland or will require major backend rewrites (e.g. getting multiple top level windows with docking working in Dear ImGui) due to lack of absolute positioning information.

2025-06-19 20:40:04 CEST

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Hopefully Debian + XFCE will keep X around for a while more.
There's still a lot of core features in X (including but not limited to absolute window positioning) that simply do not exist in wayland, and for political reasons seem unlikely to be implemented any time in the future despite being technically achievable.

2025-06-19 07:08:01 CEST

Am I a horrible computer toucher for hostnaming my MacOS bare-metal sandbox "cheddar" (as in "mac and cheese") and my Windows bare-metal sandbox "casement" (as in the type of window)?

2025-06-18 22:27:43 CEST

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how do you make that not block a manual wget or something of a large file?

2025-06-11 01:01:40 CEST

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"Tienanmen" is too hard for Americans to spell.
Lafayette Square tank man, anybody?

2025-06-08 14:58:21 CEST

Writing a unit test for a newer, faster version of a libscopehal primitive and it wasn't lining up with the original results.
Turns out there was a bug in the original (FindZeroCrossings would fail to correctly detect a crossing between samples 0 and 1).

2025-06-05 06:41:06 CEST

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It made the connector routing so much easier. Otherwise I'd have to swizzle lanes in all kinds of awkward ways with lots of mid-span vias and criscrossing. It's much cleaner this way.
https://files.ioc.exchange/media_attachments/files/114/628/910/462/560/670/original/250add9b200ac504.png

2025-06-05 06:38:48 CEST

Don't mind me, just over here escape-routing this BGA inside out
https://files.ioc.exchange/media_attachments/files/114/628/905/255/203/905/original/d1d51bc4f306b3eb.png

2025-05-29 05:01:40 CEST

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Not a problem in a point to point system.

2025-05-29 04:28:35 CEST

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This is specifically for on-board management, so range and speed don't really matter.
It's for things like the main CPU querying the temperature of the power supply, or requesting a soft shutdown / warm reboot.

2025-05-29 04:13:57 CEST

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I'm getting increasingly fed up with making SPI peripherals in software because you have unnecessarily tight hard realtime constraints to make the protocol work (if you don't respond within the set time the other side reads garbage).
In gateware you can easily enforce cycle accurate timing and on the host side the timing isn't critical.

2025-05-29 04:05:10 CEST

Thinking about switching my supervisor MCUs to use i2c instead of spi for interfacing to the main CPU.
Rationale: uses two less pins, can be combined with sensors and other system health stuff on 3v3_sb power domain, simpler code with no hard realtime constraints since you can clock stretch if the other side isn't ready, and it doesn't need to be fast at all.

2025-05-16 12:50:55 CEST

If you're writing software to control a shaker table for vibration testing...
... is that vibe coding?

2025-05-15 12:57:04 CEST

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Some familiarity with the hardware side of things is also super helpful (as I'm sure you've already been seeing).
You don't have to be an EE to be an embedded software engineer, but your code is running on physical hardware that interacts with the real world. It's very possible for bug-free code to fail due to hardware problems (something something RGMII clock inverted iykyk), or for buggy code to damage hardware or even cause physical injury to somebody under the wrong circumstances (e.g. some machine making a sudden unexpected motion).
The more you can understand the hardware the easier it will be to both collaborate with the hardware team in general, and to troubleshoot when things don't go as planned and you're not sure which side is at fault.
Also to anyone, ladies or otherwise, interested in getting into embedded - my virtual office door is always open, feel free to ask questions about anything.

2025-05-12 08:59:21 CEST

Some sales rep from Delta, Mean Well, Orion Fans, Sanyo, Sunon, or another big cooling-products vendor should set up an OnlyFans page.
And make G-rated videos showing off all of their fans, heatsinks, thermal pads, etc.

2025-05-04 07:00:08 CEST

Where should I put the grounding stud on my homemade ESD safe blahaj (ANTISTATISKHAJ)?
Modeling on a stock ikea shonk because the ESD one is a WIP
https://files.ioc.exchange/media_attachments/files/114/447/795/372/221/979/original/85eedd9d87d918ae.jpg

2025-04-28 05:25:48 CEST

Is there any about:config or similar setting in Firefox that completely disables the crash-report mechanism?
I don't mean "don't automatically submit", I mean "crash data is not saved to disk and the user cannot submit it".
I just accidentally clicked the wrong button on a tab-crash page and submitted a crash report despite a general policy of disabling all telemetry and crash reporting in all software I use. I'd like to prevent a recurrence.

2025-03-24 15:23:16 CET

Anyone (@npub10vc…3seg maybe) have GIS data showing golf courses as percentage of overall land usage across the USA/world?
I'm not interested in exact course locations or sizes, I want to know at a larger granularity (say, per county) how many square miles of golf course there are per square mile of overall land, and how this varies across larger areas.

2025-03-20 15:31:50 CET

Does anyone have a sales contact for 3M specialty abrasives (diamond lapping films etc)?

2025-02-26 16:15:10 CET

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The end goal is a new set of electronics that completely lack hardware support for any kind of phone-home nonsense and are designed for utmost simplicity and reliability, rather than giant piles of rapidly developed spaghetti code full of features nobody wants.
We know how to build safe and reliable electronics, we do it all the time for e.g. geostationary communications satellites that have to function for 10+ years without any maintenance and that would cost $100M+ to replace.
We know how to build reliable software. We just... don't. Because it's too expensive.

2025-02-26 16:12:31 CET

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You can completely sidestep DMCA issues if you replace the OEM ECUs entirely rather than messing with their firmware.
I'm talking about physically removing e.g. the BCM and engine controller and replacing them with from-scratch new ones designed to exceed the OEM safety and efficiency standards.

2025-02-26 15:54:21 CET

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If this happens, I might finally get the open-source backing and funding I need for my dream of having a "car neutering" service available.
Pick a popular recent model vehicle with decent mechanical/structural design and offer a complete revamp with new ECUs and consoles that are drop-in replacements for the OEM ones.
In rough order of priority (factoring both importance to safety/usability and complexity of implementation):
1) Remove every radio transmitter, cell modem, telematics phone-home feature, etc
2) Replace all touch screens with physical knobs and buttons
3) Remove every "self driving" / "driver assistance" feature or, at absolute minimum, add a big red e-stop button that physically powers down all ECUs and sensors providing such antifeatures and reverts to full manual control
4) Replace all ECUs responsible for safety-critical functionality like throttle control and ABS with new ones built with memory-safe firmware, triple modular redundant processors with ECC RAM, and (ideally, although this would be more invasive in terms of required modifications to the vehicle) redundant sensors and actuators so that failure of say a single pedal position sensor won't lead to a loss of control.
I think the implementation I'd trust most for life-safety software, with current technology, is probably an FPGA based platform compiled with open tools and end to end LVS from bitstream to RTL, running three copies of a riscv-formal validated CPU core with a majority voter on the outputs and SEU scrubbing on the configuration memory. The technology to build this either exists today or is close to available, although at the cost of performance vs more mainstream solutions.
Formal verification of the software control loops would be great too. Anybody know what the state of the art in formal correctness tools for Rust code (in terms of algorithmic bugs rather than the safety properties checked by the compiler and runtime) is like?

2025-02-24 17:15:55 CET

Every time I go to a bagel place that offers LOX I wonder why I can't get RP-1 or UDMH or methane instead.

2025-02-23 21:00:19 CET

Somebody should release a qemu fork specifically tuned for running really old FPGA, PCB, and VLSI tools.
You could call it "soybean".
As in EDA MAME.

2025-02-22 22:46:46 CET

Perfectly normal hotel room essentials. Nothing weird here.
https://files.ioc.exchange/media_attachments/files/114/049/730/978/957/082/original/b1911b1594529d00.jpg

2025-02-20 22:12:43 CET

Periodic reminder to the fedi EE / embedded systems community: I have a lot of lab capabilities and resources that the average hobbyist can't afford, and am willing to offer them up on reasonable terms (i.e. FREE in many cases) to help people out.
As a general rule if you're not making money on it (i.e. hobbyist/noncommercial/academic project) and it's not a major time commitment or consumable cost for me, all I ask is that you pay return shipping if you want the hardware sent back to you afterwards. For anything large or commercial in nature, I'm still potentially interested but we'd have to discuss compensation first (I offer steep discounts vs industry rates as long as you're not making a profit from the project... think $25-50 an hour for something an industry lab would charge several hundred for)
Also open to hosting occasional lab sessions for folks in person on weekends if you're Seattle local and willing to head across the water.
Capabilities and equipment available:
* 3D planar EM simulation (Sonnet Pro)
* 5 3/4 digit multimeters (R&S HMC8012)
* Various oscilloscopes to 16 GHz BW (PicoScope 6424E, LeCroy WaveRunner 8404M-MS, LeCroy SDA 816Zi-A) plus power rail, current, and differential probes
* VNA measurements to 8.5 GHz (PicoVNA 106 / 108)
* BERT BER/eye pattern/bathtub curve measurements to 28 Gbps (MultiLane ML4039-BTP)
* Vector signal generation to 6 GHz (Siglent SSG5060X-V)
* Fine pitch soldering and PCB rework, BGA assembly, inner layer circuit edits, etc
* UV-VIS-NIR (200 - 1200 nm) spectroscopy
* Low magnification stereo microscopy
* High magnification reflected light optical microscopy to ~300nm resolution, including large area automated step-and-repeat scanning and stitching of multi-gigapixel datasets
* Coming soon (purchase order sent to vendor, estimated ship date is early April): Embedding and cross section polishing for failure analysis etc

2025-02-12 18:47:37 CET

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is that some kind of multiproject wafer or something? it looks like two completely independent dies with separate pad rings.

2025-02-05 17:30:01 CET

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You know real night vision doesn't squeal like an old camera flash right?
At least nothing current generation. Maybe the ones from the 60s did. Wouldn't know, I've never used anything that old.

2025-02-01 17:43:47 CET

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Makes me wonder if gov pressure might be behind some of the constant demands to e.g. turn on google photo cloud sync.
Or if it's just google wanting more data to train their AIs on.