[Cryptech Tech] PCB prototyping machine [Was: BCP prototyping machine]

[Павел Шатов]

On 23.02.2015 12:27, Benedikt Stockebrand wrote:
> Hi Pavel and list,
>
> Шатов Павел <meisterpaul1 at yandex.ru> writes:
>
>> So you want to buy something like this for our FPGA:
>> http://www.proto-advantage.com/store/images/PRODUCTS/BGA0006_0.JPG
>
> yes (unless I can get it prebuilt with the FPGA on already).
>
>> then buy another breakout board for the CPU
>
> Yes.
>
>> and then etch a kind of a 2-layer interposer to connect them? Do I get
>> it right?
>
> Yes, if breadboard and/or perfboard/stripboard won't do the job for
> that.  And I also wand various modules to connect to as well, for
> example one for the analog noise part, and whatever else.

Benedikt, you do know what all those capacitors are there for, don't you?

http://bunniefoo.com/novena/pvt1_release/novena_pvt1e_bot.jpg

Bredboarding an FPGA is a very flawed idea. Well, you may actually be 
able to get a blinking LED with it, but as soon as Joachim crunches all 
of his cores in the FPGA, it will stop working without proper decoupling.

FPGA layout is actually not our worst problem. The worst part is that 
i.MX requires DDR3-1066 memory. GHz signals require controlled PCB 
impedance, which is impossible to get outside of a factory. How are you 
going to deal with that?

> It'll look messy like hell, and it won't be much fun to carry around,
> but it'll make experimenting much easier.
>
> When I started messing around with the microcontrollers in general that
> approach proved to be extremely useful, despite perfboard being so
> unbelievably tedious to use.

I agree, this approach works nicely with DIP and SOIC packages, but BGAs 
are completely different story.

--
With best regards,
Pavel Shatov