[eagle] Re: Revised Module Suggestion
Rick Hambly (W2GPS)
w2gps at cnssys.com
Tue Oct 16 11:01:04 PDT 2007
Don't be too concerned, just yet. I just thought it might be wise to say
this now, in public. The whole point is that there are no more private "we"
groups. Everything is in the open.
The justification for a possible IHU redesign is based on three issues:
1) the present problems with the P3E IHU-3 boards,
2) a desire to move to an open source core so that we can redesign the
registers to achieve better radiation resistance, and
3) to move toward an open source operating system like a real time Linux
variant, for example.
Right now these are just discussions but I think there is enough
justification in them to suggest we not spend time and money creating a
special package for the current board just jet. This is just my opinion, not
From: Chuck Green [mailto:greencl at mindspring.com]
Sent: Tuesday, October 16, 2007 11:38 AM
To: Rick Hambly (W2GPS)
Cc: 'AMSAT Eagle'; 'Dick Jansson-rr'
Subject: Re: [eagle] Re: Revised Module Suggestion
That's news to me. What is this secret group you called "We" and when
do they intend to include the rest of the Eagle community? Also, where
should I ship the parts that were purchased for the IHU? The developers
of this new IHU may be able to use some of them.
Rick Hambly (W2GPS) wrote:
> I think there is a good chance that the IHU will be redesigned for Eagle.
> are discussing some important changes like switching to an open core
> of the ARM core, changing the oscillator design, and other improvements.
> that is done it will be a modest leap to a new board size.
> AMSAT LM2232
> -----Original Message-----
> From: eagle-bounces at amsat.org [mailto:eagle-bounces at amsat.org] On Behalf
> Chuck Green
> Sent: Tuesday, October 16, 2007 11:15 AM
> To: Dick Jansson-rr
> Cc: 'AMSAT Eagle'
> Subject: [eagle] Re: Revised Module Suggestion
> Hi Dick,
> When considering special needs, don't forget that the IHU has already
> been designed and will need a box to accommodate it. You did this once,
> but with the new box designs, it may need to be done again.
> Dick Jansson-rr wrote:
>> There is another issue that comes to mind regarding "specialized"
>> modules. In a program such as Eagle we will need to create an
>> acceptable module design that is useful for many applications in the
>> mission and then turn on the fabrication machinery for producing these
>> long before the electronic forces are ready to populate them for
>> flight. On P3D in 1992-3 we gambled and manufactured a very many
>> module parts, expecting that we would have some spares left over -
>> wrong! Even with this quite large quantity of parts (and at that time
>> there was criticism that we were making too many) we ran out before
>> flight and had to make some more.
>> Fabricating module parts for this program is a guessing game, with
>> some estimates of needing to construct up to 80 sets of parts, and
>> that may not be enough. You can do the detailed program mathematics
>> and come up with some number and I will be willing to bet that you end
>> up on the wrong side of that guess. It's a dicey game.
>> The lesson in this is that we must create a generic module design and
>> hardware that can be adapted for many different assignments in the
>> spacecraft. Save for your specialized need, we have no indication of
>> any other specialized module needs. This is why I prefer to adapt a
>> generic module to your needs with the added heat sinks, rather than
>> make just a specially machined device just for your needs. And if we
>> do, we will probably not have enough of them. This is why I prefer to
>> have a generic module design and then carefully adapt it as required
>> for specialized module needs. We will be flying more than just the U
>> Dick Jansson, KD1K
>> kd1k at amsat.org <mailto:kd1k at amsat.org>
>> kd1k at arrl.net <mailto:kd1k at arrl.net>
>> *From:* wa6htp at gmail.com [mailto:wa6htp at gmail.com] *On Behalf Of *Juan
>> *Sent:* Monday, 15 October, 2007 15.38
>> *To:* Dick Jansson-rr
>> *Cc:* Bob Davis; AMSAT Eagle
>> *Subject:* Re: [eagle] Revised Module Suggestion
>> That looks nice! It appears to solve the issue of getting that front
>> panel at exactly 90 degrees to the baseplate and also increases the
>> stiffness of the baseplate. Increasing the useful front panel space
>> also eases the problem of working around the CAN-Do PCB with all of
>> the necessary I/O connectors.
>> Would it be possible to customize the baseplate for the few modules
>> that draw high power? It would be nice to machine the baseplate and
>> heat sinks as one chunk of metal instead of the existing method of
>> having several individual heat sink pieces. I would like to see the
>> PCB laying flat on top of the baseplate with milled cutouts to
>> accommodate any devices attached to the bottom side. In a perfect
>> world there would be no components on the bottom and the PCB would
>> make contact with the baseplate across the entire surface. Another
>> possibility that might be worth considering would be the ability to
>> include "U" shaped heat sinks that would bridge over the top side of
>> hot components and attach to the baseplate through holes cut into the
>> PCB on either side of the component. Thermal gap filler could allow
>> room for CTE mismatches so that the device isn't crushed.
>> 73, Juan - WA6HTP
>> Via the Eagle mailing list courtesy of AMSAT-NA
>> Eagle at amsat.org
> Via the Eagle mailing list courtesy of AMSAT-NA
> Eagle at amsat.org
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