[hpsdr] [ATLAS] - proposed physical bus/pcb design 03March2006

[Philip Covington]

On 3/3/06, Philip Covington <p.covington at gmail.com> wrote:
> On 3/3/06, Lyle Johnson <kk7p at wavecable.com> wrote:
> > Hello Phil!
> >
> > >>> A suggestion: I would like to see some small subset of a bus, maybe one
> > >>> of the X buses so it will be supported with a 64-pin DIN connector - be
> > >>> changes such that it is daisy chained between slots.  This makes it much
> > >>> easier to set up things like JTAG chains, slot-based priority interrupt
> > >>> schemes, and the like.
> >
> > >> Actually, I had already made a provision for this possibility.  The
> > >> XBUS (on the bottom of the board), and the YBUS (between the two plane
> > >> layers) are routed between the J7-J20 pins on their respective layers.
> > >>   The actual short traces (0.200" long) from the J7-J20 headers to the
> > >> slot connectors (J1-J6) are all horizontally on the bottom layer of
> > >> the board so you have full access to both the X and Y lines.
> >
> > > I have posted a pdf of the bottom layer (layer 4 XBUS) here:
> >
> > QSL
> >
> > I would still like the default configuration to be with a couple of
> > traces daisy-chained rather than requiring surgery on ATLAS.  If surgery
> > is required, fewer designs will take advantage of the feature, and there
> > is a greater chance that various designers will select different pins,
> > causing several wire-wrap jumpers along with multiple cuts.  If the
> > daisy chain is defaulted, it can be defeated if needed by jumpers and no
> > cuts.
>
> Got it...
>
> How about if I daisy chained the current (6) XD0-XD2 and YH0-YH2 bus
> wires?  Would that give enough daisy chained connections?
>
> 73 de Phil N8VB
>

Oops, not enough if you are only using the XBUS.  looks like we need
six lines to daisy chain all six slots if only using the XBUS.   It is
enough if we use the YBUS too.

73 de Phil N8VB

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