SPI Flash
trmm.net
trmm.net
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.
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!
I got the much cheaper and simpler clips to tolerate my abuse better.
Powering the chip will inevitable power other things around the chip, things that might also be trying to read it.
I'm thinking of something that locks through a hole in the board and then pushes 4 pins onto 4 pads on the board.
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.
[1]: https://www.macrofab.com/blog/designing-pogo-pin-programming...
https://www.we-online.com/en/components/products/REDFIT_IDC_...
(In case anyone missed it, there is a video on the page that explains how it works)
There's an example of this on Digilent's Arty development board, at the top of the board between JB and JC:
https://digilent.com/shop/arty-a7-100t-artix-7-fpga-developm...
More here: https://www.we-online.com/components/media/o210254v410%20ANE...
Very nice alternative to Tag-connects. It looks like the PCB footprint is a little larger per pin but the connector is less fragile and the connection would be more robust. Great for having a debugger or logger attached during lifecycle testing especially in the prence of vibration. I also find their other suggested use - enabling expansion connections with no added cost to the base unit - very intriguing. "Options" are very typically higher margin than base products so having a way to enable adding them that does not add a connector to every unit has a lot of potential use cases.
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.
s/ of/'ve/
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...
If you're willing to go through hole then you can layout a 2 by X row header with the rows slightly too close together. So when you insert a header it will pinch the pins and make a good connection.
If you're willing to put a row of pins at the edge of the board you can place it so it pinches the pins between the holes and the edge of the board.
Most of this knowledge has been lost (this was like 20 years ago), but wikipedia mentions the "sombrero de patel" (because it's like a PCB "hat" over the mainboard) here: https://en.wikipedia.org/wiki/Pirate_decryption
Since they only needed to extract a small key, it had 1-2x Atmel 8515s to do the work (which were used for other paytv applications, so not hard for people to scrounge once they build the board).
Why don't all the others have this feature?
They are not hosted by trmm? :)
I have also added some reliability improvement (IMO), but it may be more or less reliable for you.
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.