Adam Wang wrote:
> Rough illustration above, here's a frame marked on M1r3 pcb:
> http://downloads.qi-hardware.com/people/adam/m1/tmp/m1r4/M1r4_expansion_board_frame.png
Ah, very nice. Thanks ! Seems that Y1 is the tallest component
(5 mm) we have below the board, followed by C69 and C240 (2.5 mm).
This limits the space we can allow for components on the bottom
of the extension board. Is there any chance to find a crystal
that's a little flatter ?
For the vertical clearance, I would like to have a safety margin
of about 2 mm, to account for small design oversights, flexing,
lumped tolerances, and such.
Safety margin = board to board spacing (about 10.6 mm)
- tallest component in area on M1
- maximum height we allow on bottom of board.
With Y1 = 5 mm, this would leave only about 3.5 mm for the
extension board. We could define different height zones, but I
think that would make the specification just too complex.
We also looked at how the DVI-I connector would change the space
situation. This part seems to be common:
http://search.digikey.com/us/en/products/74320-1004/WM5600-ND/356066
Does it look right to you ?
Compared to the current VGA connector
http://downloads.qi-hardware.com/hardware/milkymist_one/datasheet/VGAOut/D11215SXX31XN.pdf
it would be wider (36.83 > 30.81 mm) but less deep (10.95 < 13.97
mm from PCB edge), and also a bit lower (9.91 < 12.55 mm). So this
sounds good.
- Werner
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