Great idea. I like it. Let's discuss at Thur eve meeting.
Good evening,
I thought some more about how going to two boards might work
layout-wise. My first thought was that it would be very undesirable to
go to two boards, as we take up stack space which could be allocated
to other experiments. With conservative planning on the flight board
and some work to limit excess components on the current design, I
think it's entirely possible to fit the flight model on one board.
Looking at the board space we have available (~26 in^2) and the
current schematic, there would be several steps I would take before
going to another board. First, we have a lot of bottom board space
which isn't used at all. Pullup resistors on the digital side, power
supplies, and even the CPU could be placed on the bottom of the board.
Just by removing the UFL connectors and replacing the 0603 components
with 0402s, we'd save around an inch for practically nothing.
Additionally, more layers on the board may allow greater route density
on the top and bottom layers. I think that 8 or 10 at maximum will be
sufficient and provide a shorter path than a second board would allow.
I made an *approximate *placement diagram which shows the current
configuration and possibilities for the new board.
I'm not opposed to multiple boards for development purposes. We could
break all the circuits out onto different test platforms which could
be distributed to more people for software development. We could
troubleshoot each section individually before combining onto the
flight model. I think for the best performance on the flight model, it
should be a single board.
Something Bill pointed out in the meeting was that heat dissipation
might become an issue with so many components packed onto the board.
While the board can do a lot to sink heat, perhaps additional sinking
will be necessary. On the RT-IHU, we plan to create a heat spreader
which presses a ceramic block onto the TMS570. Originally, this was
going to also have milled cavities to act as shielding for the
components, but the design was shrunk for unknown reasons (something
that Bob Davis had been working on). Perhaps something like this might
be beneficial, although it would be expensive and add weight and
height. Just a thought.
This is my point of view from the layout side. While a challenge, I
definitely think a single board is possible. Thoughts?
Thanks,
Cameron
Cameron Castillo
KJ7ILB
/P/: (503) 752-8877
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