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

[Lyle Johnson]

Hello Phil!

> For those interested, I'd appreciate if you'd please take a look at
> the documents and make questions/comments.

In general I like what I see.

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.

Foe example Bus XC[0:7] could be broken into XC[0:3] as at present.  The 
present wiring of XC[4:7] going to pins A[22:25] might be rewired like this:

J1    J2    J3    J4    J5    J6
A22---A22   A22---A22   A22---A22
A23   A23---A23   A23---A23   A23--- to J1 A23 or n/c
A24---A24   A24---A24   A24---A24
A25   A25---A25   A25---A25   A25--- to J1 A25 or n/c

I realize this can be done by cutting on the board, but the X traces are 
inner layer and the Y traces are only on the 96-pin connectors.

Alternately, this could be done on the Y traces and just accept the fact 
that this is a "high end" feature and thus only supported on 96-pin 
boards.  This restriction, however, means that any intervening boards 
must also be 96-pin, which limits it usefulness.

73,

Lyle KK7P


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