[Cryptech Core] Alpha rev.03

[Peter Stuge]

Fredrik Thulin wrote:
> > What kind of cable or board was so far used to connect to STM32_SWD?
> > The ST-Link?
> 
> Yes, flat cable to the ST-LINK on NUCLEO and DISCOVERY boards.

Ribbon cable? They're usually terminated with 2-row .1 inch connectors,
but the Alpha has a 1-row header. Hmm. I'll look at the Discovery board.


> you should be able to route the SWD signals through your board

That's the plan.


> I think your board won't fit in the case with standard pin header
> mating with the top on.

I'm using 7.2mm bottom-entry receptacles. The header pins pass
through my board.

Assuming a standard 1.6mm PCB that's 8.8mm over the plastic base of
the pin headers on the Alpha.

I can't open the Excel BOM but looking at it in a text editor I don't
spot a part number for the headers, so the assembly house will pick
what they have.

In a random header family PDF I see mating lengths of pin headers
between 5.84mm and 13.21mm.

So now I have to review also the case and cutout position.

Bottom wall thickness is (30.51 - 27.51) / 2 = 1.5mm

Distance from inside of bottom to first slot is 5.69mm

Each slot is 2.0mm, distance between slots is 1.5mm

Distance from outside to third slot bottom is 1.5+5.69+2+1.5+2+1.5 = 14.19mm
(Panel PDF says 14.1mm)

14.19 + 1.6 = 15.79, so top side of PCB position 15.8mm is good.

Remaining distance to inside of lid is 27.51 - 15.79 = 11.72mm

This tells us that 15.3mm to bottom of the rectangular cutout is good.

A random header has 2.54mm of plastic, leaving 11.72 - 2.54 = 9.18mm

So my board should fit in the case with 0.3mm to spare.


I am unable to review the 7mm hole for the DC jack, because the
rev03.pdf schematic I have calls the jack JP1 with 694106301002 as
only reference, and the Excel BOM in my text editor seems to suggest
that JP1 is a 1x2 header. Dunno.


//Peter