[HN Gopher] SPI Flash
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SPI Flash
Author : todsacerdoti
Score : 137 points
Date : 2024-06-02 14:21 UTC (8 hours ago)
(HTM) web link (trmm.net)
(TXT) w3m dump (trmm.net)
| bee_rider wrote:
| It is about hardware stuff. Just in case anyone as dumb as me is
| expecting something about triangular matrix multiplication, given
| the url. Haha.
| amelius wrote:
| Side question. Does anyone have a good method of attaching 4
| wires (say for a programmer) to the middle of a board, preferably
| without soldering any connector on the board? (Edge connectors
| are too bulky and inconvenient).
|
| I'm thinking of something that locks through a hole in the board
| and then pushes 4 pins onto 4 pads on the board.
| asguy wrote:
| Something like a Tag Connect would work well, if you can spare
| the footprint space: https://www.tag-
| connect.com/product/tc2030-fp-footprint
| the__alchemist wrote:
| I use these: 6 pin for connecting to St-Link.
| _moof wrote:
| Tag Connects are great. I use them on all my boards. Small (I
| use the "no legs" version), no BOM item, and works
| beautifully.
| jhallenworld wrote:
| I like Tag's new Edge-Connect- we tried them, they are
| awesome:
|
| https://www.tag-connect.com/product/ec06-ctx-20
|
| These take much less board space (especially when considering
| locking holes) and work much better than Tag-Connect with and
| especially without the locking holes (those pin lock things
| are available, but they suck)- I mean they are easy to insert
| and stay in place, very nice for firmware people to use. They
| seem ambiguous about which side of the board you can plug
| them into, but they are actually (barely) polarized.
|
| The main disadvantage is the expense of the connector and
| expense of castellated holes on the edge of your board. If
| you can afford the BOM cost use a surface mount 10-pin 50-mil
| header, or if you can afford the footprint space and some
| holes, use the SKEDD connector.
|
| BTW, for SPI-flash chips: an option is to use a socket for
| them.
| magicalhippo wrote:
| For your own boards, there are connectors like this[1], based
| on pogo pins.
|
| [1]: https://www.macrofab.com/blog/designing-pogo-pin-
| programming...
| elsjaako wrote:
| There's the SKEDD from WE, no experience yet, but it's on my to
| do list.
|
| https://www.we-online.com/en/components/products/REDFIT_IDC_...
| amelius wrote:
| This is exactly what I was looking for!
|
| (In case anyone missed it, there is a video on the page that
| explains how it works)
| ajross wrote:
| The "middle", as in you want to tap a trace and not a pin on a
| chip? You really can't without hacking at the board somehow,
| there is a plastic resist layer on all the traces. They're
| usually visible through it but without scratching a hole you
| can't get to it. And then of course the signals you actually
| care about are just as likely to be in middle layers you can't
| reach without destroying something above/below it.
| amelius wrote:
| No, "middle" as in not necessarily near the edge of the board
| ;)
| tommiegannert wrote:
| I designed these a while back to 3D-print cable housings for
| pin headers. Also made one for cheap pogo pins:
| https://cad.onshape.com/documents/30e7754831a9aa479c6cd5ac/w...
|
| For one-off things, since they (right now) require glue, and
| it's fiddly. But I like being able to churn out any number of
| pins quickly. Adding keys that stick out and attach to holes in
| the PCB, like the other examples mentioned in other comments,
| sounds nice.
|
| Related to the article: There's also the possibility of using
| DIP sockets with flexible legs (not the lathed ones). By
| bending them in an S, you get a spring loaded contact. I made a
| housing for it, to be used as a non-intrusive snooper on DIP
| EEPROMs.
| XMPPwocky wrote:
| For board you didn't design, PCBite probes work, but can be
| fiddly especially when you have several've them in a small
| area.
| myself248 wrote:
| Seconding PCBite probes. They're weighted, the force comes
| from gravity not from flex/spring in the arm, which confuses
| a lot of people at first. But they work pretty well.
| noman-land wrote:
| What two words are you contracting with "several've"?
| dcassett wrote:
| Probably "several of"
| XMPPwocky wrote:
| Yeah- I started being "flexible" with contractions in
| casual online speech years ago as a joke, but now it's
| just sort of part of my "dialect". That and cursed
| multiple contractions; at least I'ven't'd any problems
| with accidentally using either of those in formal speech.
| noman-land wrote:
| That's really funny. I personally can't abide by flexible
| contractions but the multiple contractions are definitely
| up my alley and I deploy them whenever I can.
| jwiz wrote:
| It almost seems like an overreaction for correcting "should
| of".
|
| s/ of/'ve/
| vbezhenar wrote:
| For some chips you can use test clips like these ones: [1].
| You're using a tiny hook to attach wire to the chip pin
| (assuming that it's exposed a bit.
|
| Another option is to use needles like [2]. You just put them
| wherever needed and wire makes sure that it sits there. It's
| fragile, but for some quick checks might be OK.
|
| 1: https://www.saleae.com/products/test-clips-93
|
| 2: https://www.saleae.com/products/pcbite-kit-
| with-4x-sq10-prob...
| 15155 wrote:
| Tag Connect is hard to beat
| ttul wrote:
| "I'd especially like to thank three colleagues, Thor Simon,
| Viktor Dukhovni and Larry Rudolph for their assistance on this
| project."
|
| That's Victor Duchovni, inventor of the Postfix MTA. Two Sigma,
| founded only back in 2001 (i.e. newer than Google), has certainly
| done well in retaining some incredible people on the software and
| computer security side. From what I've heard, it's a fantastic
| place to work as an engineer. They give people lots of
| independence to work on things they consider to be important,
| which is really exemplified by this blog post.
|
| I think many larger financial firms would just outsource their
| Apple security, but Two Sigma has an engineering poking around
| the hardware and making novel discoveries. That kind of thinking
| is how you actually get ahead in securing an enterprise, IMHO.
| teddyh wrote:
| It was Wietse Venema who wrote Postfix.
| ttul wrote:
| You caught me in a senior's moment. Whoops.
| kelsey98765431 wrote:
| Oh my goodness good morning and hello! Rarely do I get to see a
| treat like this on a sunday. Thank you!
| neilv wrote:
| As someone who's only dabbled lightly with electronics, maybe I
| was just doing it wrong, but I didn't have great luck with those
| Pomona SOIC test clips.
|
| While doing in-circuit SPI flashing of several laptops for
| Coreboot, getting a good read or write was difficult. One of the
| many things I'd regularly try was to reseat the clip.
| Unfortunately, with the Pomona clips, this reseating would tend
| to catch and push in the pins of the clip, so they started making
| even poorer contact.
|
| This pushing in was possible because there's not a single rigid
| pin straight through from the component to the test headers. The
| pin is 2 or 3 (I forget) parts, and a lower part can pop out of
| the plastic channel/groove it's in. You can disassemble the clip
| and push things back together, but it wasn't quite the same as
| before deformed.
|
| I ended up having better luck with simpler clips that have a
| single physical pin straight through, such that the header pitch
| is the same as the component. Then I bent the pins to the side in
| an alternating pattern, to give enough room to attach my
| individual wires.
| baby_souffle wrote:
| > I ended up having better luck with simpler clips that have a
| single physical pin straight through, such that the header
| pitch is the same as the component. Then I bent the pins to the
| side in an alternating pattern, to give enough room to attach
| my individual wires.
|
| I have had 100% the opposite experience :D. For whatever
| reason, the cheap clips quickly develop intermittent faults on
| some number of wires or the pin deforms hopelessly. You can
| tell the problem is getting worse when you have to maintain
| more pressure to hold the clip in place or do multiple reads
| and confirm that the sha1 hash of the dump file matches for the
| majority of reads!
| neilv wrote:
| Maybe I just had clumsy technique. I was usually attaching
| the clip with not much room to open it beyond the component,
| which I guess might've contributed to pushing in the
| component-side pins.
| lemonlime0x3C33 wrote:
| I love Pomona SOIC test clips, the other cheaper ones off of
| amazon are garbage though. :) I find when flashing hardware you
| might have to try a few times and if you get a good read/write
| going don't move, don't breathe, don't do anything until it is
| done.
| schmidtleonard wrote:
| Was it Pomona or Pomona knockoff? IME the real ones are eye-
| wateringly expensive but they actually work, whereas the
| knockoffs are dirt cheap and tend to require even more effort
| than soldering (between making initial contact and
| discovering+fixing intermittency problems).
| neilv wrote:
| It was Pomona-branded. They were either genuine, or very
| convincing-looking counterfeits. I had a few of them, and the
| materials and build quality seemed good, other than pin
| migration up that my use/abuse of them seemed to cause.
| dishsoap wrote:
| If you didn't pay upwards of $20 per piece, they were
| likely fakes. I have had the same experience as all the
| other commenters here: Pomona clips are the only ones I've
| found that actually work well, while all the cheap clips
| are just about unusably bad.
| pstrateman wrote:
| You can get lots of very weird results trying to read a chip this
| way.
|
| Powering the chip will inevitable power other things around the
| chip, things that might also be trying to read it.
| _moof wrote:
| Yeah, it's best if you can also hold down any reset lines on
| other things on the board.
| jayyhu wrote:
| Also you could potentially damage the on-board voltage
| converter/regulator, since most aren't designed to be back-
| driven from their outputs.
| mjg59 wrote:
| You can frequently avoid this by running at a lower voltage -
| SPI chips are often rated to run down to under 3V, and
| associated components will tend not to run with that much power
| userbinator wrote:
| On PC mobos it's usually not a problem as the BIOS is
| programmed after assembly. I've seen laptop repair shops in
| China do it all the time.
| gtsnexp wrote:
| Huge fan of Trammell Hudson. Not sure why he simply stopped
| posting after 2021. Loss to humanity.
| transpute wrote:
| https://social.v.st/@th
| karma_pharmer wrote:
| Wow, this mastodon interface works without javascript!
|
| Why don't all the others have this feature?
| transpute wrote:
| _> Why don 't all the others have this feature?_
|
| They are not hosted by trmm? :)
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