metaphor

[1] https://news.ycombinator.com/item?id=24359220

Looking at the normative language of the early DP v1.1a § 3.3 Hot Plug/Unplug Detect Circuitry:

> The HPD signal is asserted by the DisplayPort Sink whenever the Sink is connected to either its main power supply or “trickle” power. HPD signal specification is shown in Table 3-2.

To be sure, HPD assertion on "trickle" power is the monitor's requirement.

Looking closer at Table 3-2 (empty Nom col removed, Comments col separated for clarity):

  | Parameter                          | Min  | Max | Units | Comments |
  | ---------------------------------- | ---- | --- | ----- | -------- |
  | HPD Voltage                        | 2.25 | 3.6 | Volt  | (a)      |
  | Hot Plug Detection Threshold       | 2.0  |     | Volt  | (b)      |
  | Hot Unplug Detection Threshold     | 0.8  |     | Volt  | (b)      |
  | HPD source termination             | 100  |     | kΩ    | (c)      |
  | HPD sink termination               | 100  |     | kΩ    | (d)      |
  | IRQ HPD Pulse Width Driven by Sink | 0.5  | 1.0 | ms    | (e)      |
  | IRQ HPD Pulse Detection Threshold  | 2.0  |     | ms    | (f)      |

> (a) HPD signal to be driven by the Sink Device

> (b) HPD signal to be detected by the Source Device

> (c) Source Device must pull down its HPD input with a ≥ 100kΩ resistor.

> (d) When a Sink Device is off, it must pull down its HPD output with ≥ 100kΩ resistor.

> (e) Sink generates a low going pulse within this range for IRQ (interrupt request) to the Source

> (f) When the pulse width is narrower than this threshold, the Source must read the link / sink status field of the DPCD first and take corrective action. When the pulse width is wider than this threshold, it is likely to be actual cable unplug / re-plug event. Upon detecting HPD high, the Source must read the link / sink status field, and if the link is unstable, read the link / sink capability field of the DPCD before initiating Link Training.

Then just below Table 3-2:

> The voltage level of the HPD pin is monitored by the Source Device. TTL levels must be used for the detection.

> The Sink Device may detect the presence of the Source Device by monitoring the DC voltage level of the AUX CH lines. Source detection is an optional feature of a Sink Device.

Based on this language and description of noted workarounds, color me unconvinced that DP spec ambiguity was the root cause of this issue.

Sounds colorful. Can you cite the requirement and revision of the standard referenced? I'd like to read the actual verbiage for myself.

> Most of the support on (their DisplayPort 1.2 KVM offering) have been down to bad or dodgy DisplayPort cables. Seriously, it's like sort of nuts. Like you go on Amazon, you order a DisplayPort cable, it doesn't work, and it's like, "Well, I have two DisplayPort cables that work independently, but when I plug both of them into the KVM, it doesn't work." The KVM doesn't have a repeater. So if you've got two 6-ft cables that pass through the KVM, it is like as if you have one 12-ft cable, and while one 6-ft cable might work, 1 12-ft cable will not because...(Jedi hand gestures)...repeater. So use good quality cables, you'll be fine.

Ignoring the "repeater" terminology wank, that soundbite disclosed enough about the white label device's internal architecture for me to infer with confidence that even if EDID was properly implemented (the easiest part), the video interface is skimp and doesn't actually buffer frames in realtime...which means that on switch, the monitor's receiving ASIC will detect frame interruption as it starts to receive its new stream and blank for a second or two while it tries to reacquire...which is definitely not the instantaneous performance I was looking for.

[1] https://youtu.be/0b0_yz-oDjQ?t=74

And if the product under consideration does brandish a trademarked USB logo but clearly doesn't satisfy some observable aspect of the spec, then it's liable to be a counterfeit and you should seriously be questioning the integrity of your source.

[1] https://www.usb.org/logo-license

1. Choosing 5015 spec: as if this deprecated standard's threaded mating interface isn't super annoying to handle, you'll likely only encounter select insertion patterns of this circular interconnect spec on well-designed modern systems for high power interfacing, whereas this toy uses it for...low voltage GPIO.

2. Choosing AlCd olive drab finish: likely for no other reason than it looks "mil spec". Cd is a heavy metal useful as a sacrificial corrosion inhibitor that allows the interconnect to satisfy a 500 hr salt spray performance requirement...but Cd is toxic and can be absorbed through the skin via contact. You won't be seeing much of this once preferred finish on new designs these days.

3. Choosing front side receptacle mount: makes disassembly and servicing more difficult than it needs to be, especially given solder cup termination...made even more difficult to access by a seemingly nonfunctional spacer plate.

4. Interconnect spacing: clearly unfamiliar with 1472 human engineering requirements...I'm liable to suspect the designer has never actually attempted to mate both plugs simultaneously...may be in for a surprise, and if they happen to clear, it'd be by a gnat's ass and a significant encumberance to do so.

Food for consideration: since 3M is a ECIA member manufacturer[1], if the source isn't direct from the cow's mouth or one of their authorized distributors, it's prima facie suspect in my eyes and cannot be trusted on anything with skin in the game.

[1] https://www.trustedparts.com/en/manufacturers/3m

Hasn't this been the meta since ever since?

Imagining you'd know all about that with camarades. It was my first exposure to web streaming as a teen way back in the day. Initially, it didn't strike me as a porn platform, but it didn't take long before it felt that way.

I'm genuinely confused what is meant by this in practice. Like some sort of redundant ALU architecture or rad hard encapsulation?

https://www.militarytimes.com/news/your-military/2020/06/16/...

Bummer, and a real shame given how seemingly common regressions are in this space. Not my specialization, but anecdotally over a decade or so, I've encountered scenarios on MAX 7000 and Cyclone II (Quartus II v9.0 builds, v10.x breaks), Virtex-7 (Vivado v2018.3 builds, v2019.1 breaks) and Virtex-5 (ISE v14.6 builds, v14.7 breaks).

What's the software requirement side look like? Intel's website[1; under Legacy Devices] says Quartus II v9.0 was the latest release that could target FLEX 10K devices. Doesn't look like you can download that release anymore, and liable to run into compatibility issues just installing on modern OSs without a VM.

[1] https://fpgasoftware.intel.com/devices/

The devil in the details is that when 5V-tolerant I/O are naively configured as such, device reliability drops like a rock. You'll likely find this disclosed in the manual fine print. Something to consider when prototyping a design destined for production.

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...and if your bank happens to suck, then the loss of getting owned by one is now your problem, not theirs.

> Flipper is made by makers who got tired of all these rough PCBs and bulky external modules.

Roadmap says DFM was last month, so hazarding a guess that this won't find its way into v3 release?

Superficially, perhaps. But the zipper inclusion makes your example the "strategic" difference that properly considers the importance of what might be stored in such a pocket. IMHO, the author's approach is overshadowed by cost cutting, where the narrative serves to distract the reader with discourse on "method" that doesn't quite align with the original problem description.

I can't help but see this pocket as a liability; a cost-saving excuse to omit a proper securing mechanism of sorts shrouded by a pitch of being innovative. In a perfectly postured world with 2 operational modes--standing and sitting--this might be good enough, but I'd hardly be willing to risk yet another $600+ cellphone to find out when I'm crouching, squatting, gargoyling, kicking legs up, riding a bike, in a sports car bucket seat, etc.

Furthermore, if it's easy for you to slip your phone in and out of, then it'll also be easy for thieves to do so as well.

  s/(\w+)@(\w+)\.(fastmail\.fm)/\2@\3/g

> ...the resulting [cable] design uses G.657 200 micron fibers with a specially tailored aramid configuration and a high-strength, high-temperature, track-resistant polymer jacket to survive the requirements of this application within a small form factor.

...and the first thing that popped into my mind was a certain pain-in-the-ass-to-repair weapon subsystem which uses a certain HP/LF transmission line that also leverages a "specially tailored aramid configuration" inner jacket. Cool tech, but yikes if commercial ISPs embrace this without seriously considering sustainability implications.

It was so long ago, I had to dig up notes.

On the performance side, the counterfeits I received couldn't be clocked anywhere near the 10 MHz limit specified by a genuine MAX7219; one package pin that should be tied to GND was floating internally (contributing to poor thermal performance); but the real showstopper was that intensity control didn't work for shit.

My records reflect nigelectronics on eBay as the counterfeit seller. This is the address I was instructed to return the counterfeits to when I called them out on it for a refund (I eventually got the refund, but threw these counterfeits in the trash where they belong):

  Cheng Kwok Hang
  15F, BLK 1, Aldrich Garden, 2 Oi Lai Street, Shau Kei Wan, Hong Kong

This was my first semi-pro side gig out of college, and juggling all the unexpected curve balls with a fulltime day job was quite stressful.

I poke fun at the OP because his qualifier for "works fine" is an indeterminate definition of eventually establishing some semblance of compliant 1-wire communication with a counterfeit component without even so much as batting an eye to question the accuracy of the sensor measurement being read in, let alone:

  a) environmental constraints
  b) electrical constraints
  c) timing constraints
  d) system integration considerations
  e) counterfeit variance/unpredicability

First, on design. In your cited app note, Maxim explicitly denotes from the onset:

> Operating a 1-Wire network beyond the limits or disregarding advice given in this document may result in unreliable network performance.

The key operator that I see here is "beyond the limits", to which Maxim engineers appear to have done a fair job of specifying. Indeed, there's a lot of fine print in the published datasheet[1] alone on "parasite power mode", but a first pass suggests this is nothing more than a nuanced design challenge, not one of questionable reliability. If your long 1-wire network works today but not tomorrow, then it's difficult to swallow attribution of the issue to a singular authentic component constrained by documented performance specs rather than the system's overarching design.

Second, on reliability. Since practicing engineers don't have the leisure of independently validating every bit of specified electrical minutae, we generally have to extend some level of trust to what the component vendors specify in datasheets unless presented with evidence to the contrary (because bugs). I poke fun at your "works fine" remark above because it reads like what you care about is some semblance of establishing trivial, intermittent communication while handwaving the accuracy of the reported temperature measurement, especially given all the effort to demonstrate and document that the physical implementations of these counterfeits are clearly different...which renders the reference datasheet null and void in its entirety...which I therefore conclude nothing about these counterfeit sensors can be trusted in any application with meaningful skin in the game. To describe these counterfeits as "somewhat reliable" strikes me as somewhere between naively optimistic and outright delusional.

But hey, your hardware, your problems...just saying. :)

[1] https://datasheets.maximintegrated.com/en/ds/DS18B20.pdf

You know you're dealing with counterfeits and you know they're unreliable, but you've somehow convinced yourself that despite all the uncovered variance sitting on the table, if you keep poking long enough until the component returns some non-edge-case value, then it "works fine".

I must have hopped on the sanity train quicker than I should have because it seems like I'm missing something critical in the narrative here.

At least that was my experience 8 or so years ago when I made the mistake of purchasing a lot of 100 MAX7219 off eBay for $100 shipped from China...$1/ea was such a tempting deal to a younger, more naive self when these chips were selling for upwards of $7/ea from ECIA-authorized distributors at the time.

Never fell for that trap again.

This variant was once offered in the US market something like a decade ago for "business-rugged" use under the Toughbook brand, but that magnesium exterior shell commanded a high price point; I suspect the ThinkPad T series would have been a direct competitor at the time with better performance options and being much cheaper.

[1] https://www.gatech.edu/academics/masters-degree-programs

[1] https://www.fluke.com/en-us/product/calibration-tools/pressu...

[2] https://ashcroft.com/products/pressure_gauges/digital_gauges...