[Milkymist-devel] Placements

[Adam Wang]

Hi,

>>2, FPGA's most decoupling capacitors are located underneath fpga (bot side).
> Does this imply we have to use blind vias? Is the PCB manufacturer OK with
> that?

Exactly correct. PCB maker here is OK.

> This is not mandatory. Typically J3 would connect to a cable and not be
> accessible directly from outside the case... and it's only intended for
> "advanced" users. You can place it wherever it makes your job easier.

Ok.

> * Do you think the SDRAM is close enough to the FPGA? In [1] Micron recommends
> 2 inch (5cm) total maximum track length for systems that use series
> termination only. However, I know some designs which works apparently without
> meeting this requirement, the OLPC XO for example. Are you able to perform
> IBIS simulations?

Yes, it's close a bit but also knew some designs without meeting.
I am not able to use IBIS due to not familiar with this field.

> As I said in my first email, serpentine traces won't be needed: we'll use the
> IODELAYs instead, which do not pose their signal integrity issues.

I've used serpentine traces on DVR system. The length about
transmission becomes more seriously. However, haven't seen this useful
IODELAYs feature said, would like face this powerful practically. But
if insist on using recommends, I can add length.

> * The MicroSD connector should be placed near the JTAG and UART connectors so
> that it is accessible through a single door when the board is cased. It should
> not be placed near the board edge. This model opens on the top and the MicroSD
> card is laid on it by the user (not slided into it) then the connector is
> closed to make the contacts.

Ok, will place them close and send you again.
Thanks,
Adam