Mastodawn

✧✦Catherine✦✧4d ago

first impressions of the Lego smart brick, before I do any actual tearing down: wow, I forgot how good they are at working with plastic. the injecton molding remains impeccable, at least for this specific piece (I know about their recent QC issues elsewhere)

it's hard for me to look at the positively microscopic (I am literally using a microscope to look at it) "Li-Ion" lettering and think of anything but "showing off!"

(treehouse doesn't let me attach the full size images, you can grab them here: front, side)

✧✦Catherine✦✧4d ago

on the side, there are microscopic openings for the speaker to move air through. I would have really liked to be a fly on the wall in a meeting with the mold engineer who had to make this happen

✧✦Catherine✦✧4d ago

I'm not yet sure how I'll open it up. I don't have a hacksaw (somehow... I should fix that), so my options are somewhat limited: it's either cracking or melting plastic. from what others have done I know I there's plastic welding all around the joined region.

✧✦Catherine✦✧4d ago

okay I've decided on an idea: I will heat up the plastic to make it pliable and then cut it with a knife

as a knfe girl, this is my professional obligation.

✧✦Catherine✦✧4d ago

here's a video that shows in more detail the moldwork in the transparent plastic part

✧✦Catherine✦✧4d ago

if you've never heard of anybody opening welded plastic this way, i can now tell you why: because it's a bad idea. until you heat ABS to the point where it flows (which you don't want here, as it'll make later teardown even worse), it acts rubbery. imagine cutting hot rubber. doesn't work

✧✦Catherine✦✧4d ago

it did however let me lop off the top of it easily

this is I think a 2.4G antenna?

next step is sanding

✧✦Catherine✦✧4d ago

yep that did the thing. probably should've started with sanding at the beginning.

it was somewhat more destructively than i wanted, but that's ok: i was trying to challenge my (incorrect) belief that sanding is always a tedious pan in the arse

✧✦Catherine✦✧4d ago

took it apart. there's a sort of a plastic "carrier" that gets manufacured first, then inserted into the final package that's welded shut

✧✦Catherine✦✧4d ago

okay, i've extracted the firmware-bearing parts. this is a tiny 45 mAh battery. (part of the lettering was torn off by the glue it was attached with)

✧✦Catherine✦✧4d ago

close-ups of the component side (well, the side with more components)

originals: 1 2

✧✦Catherine✦✧4d ago

EM9305 is an em|bleu microcontroller in QFN

@whitequark Calling an ARC CPU industry standard is very funny to me

@ldcd @whitequark
It is quite widespread, even if not visible to end users.
Being in most Intel CPU's and all that.

@ftg @whitequark yeah that's why it's kind of funny, it is simultaneously a very common CPU and a very obscure CPU (ie it's hard to get comprehensive documentation, the devkit is literally an FPGA, etc)

Like they're not lying but they're trying to imply it's a normal CPU to use and be able to program which isn't really true

Graham Sutherland / Polynomial 4d ago

@ldcd @ftg @whitequark I have yet to come across any SoC with an ARC core where the docs weren't partially or fully NDA'd, or at least gated behind a sales call.

Andrew Zonenberg

@gsuberland @ldcd @ftg @whitequark stm32mp2 has an arc in the memory controller that you get a blob for, but you can dev for the rest of the chip (aside from the gpu and some corners of the pcie) with no ndas. So relatively open by that standard

Graham Sutherland / Polynomial 4d ago

@azonenberg @ldcd @ftg @whitequark yeah I'm more thinking about ARC as the main core rather than something buried doing a supporting task tho

I know Synopsys loves shoving them in everything and anything.