RE: [amsat-bb] Flight Computers

["Assi Friedman" <4x1kx@xxxxxxxx>]

One thing which I though was a great design feature on ASUSat1 was the fact
that the bootloader was OS independent. We did go with SCOS, but we could
have loaded others as well. Granted there are hardware limitations on the
system, an OBC is usually designed with an RTOS in mind. The Linux craze has
gotten everyone buzzing about porting it to everything. As much as I support
Linux, I haven't seen lots of good embedded ports for it. Another issue, is
that not that many people know how to port it properly.
As an OS, even though SCOS is currently being scrutinized by the list, it
has a small footprint and can be loaded easily to a low rate spacecraft. The
industry favorite VxWorks is much much larger. Spacecraft designers and
operators have to take that into account when designing a system.
Assi 4x1kx/kk7kx


***************************
Assi Friedman
Cell:  (602) 821-5272
email: 4x1kx@iarc.org
http://www.iarc.org/~4x1kx
**************************



-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
Behalf Of Rick Hambly (W2GPS)
Sent: Monday, April 29, 2002 8:41 AM
To: 'Lyle Johnson'; 'Jim White'
Cc: amsat-bb@AMSAT.Org; 'Chuck Green'; 'Lyle Johnson'
Subject: RE: [amsat-bb] Flight Computers


Lyle,

I just spoke with Ron Parise at NASA.  They are using both RTLinux and
RTEMS in flight computers.  Ron has solid justifications for using
RTLinux, in particular, for the IHU.  He has offered code and guidance
but we still need a lead developer.

I understand all the reasons to stay with SCOS but I would like offer
these counter arguments.

1. Nothing will be familiar to the command stations - we are going to
have new command stations.

2. RTLinux is not completely unproven.  Just not in the Ham community.
Besides, how will we advance the state of the art if we stay locked in
the safe past.  SCOS was new once, too.

3. We have re-scheduled the launch so that we have the time if we have
the desire.

4. Most of the people will be new anyway. Operation may take on a
completely new paradigm such as an ssh link to the on-board Linux
process, complete with file management, etc.  This environment and its
command structure is familiar to hundreds of AMSAT members whereas the
existing commands structure is not.

5. SCOS can be co-loaded if necessary.  SCOS can be a safety backup
rather than making RTLinux an experimental OS.  It's just a mater of
philosophy.

Keep in mind that all this is just a mental exercise at this point.
There are additional justifications that I would rather save for phone
conversations.

Rick
W2GPS



-----Original Message-----
From: Lyle Johnson [mailto:wa7gxd@fidalgo.net]
Sent: Monday, April 29, 2002 10:46 AM
To: Rick Hambly (W2GPS); 'Jim White'
Cc: amsat-bb@AMSAT.Org; 'Chuck Green'; 'Lyle Johnson'
Subject: RE: [amsat-bb] Flight Computers


Hello Rick!

My 2 cents: use the new OS for the experimental payload, leave SCOS on
the V53.  WHy?

1) The V53 running SCOS will be familiar for the command stations.
2) It is proven - we are not adding risk tot he mission.
3) It takes pressure off of the development and especially testing of
the new OS.
4) The last thing you want to have is a new command suite of software
being learned and debugged by the people who need to ensure the safe
operation of the spacecraft.
5) Since it is soft-loaded, you can always replace SCOS with the new OS
after it has been proven reliable, safe, etc.  If this happens before
launch, so be it.  If not, see 3 :-)

For the experimental payload running the digital communications system,
go for it!

73,

Lyle

> I saw your message about flight computer software on AMSAT-BB.  I am
> looking into using an open source operating system (RTLinux, RFEMS,
> etc.) for either or both of the processors on AMSAT OSCAR-E (AO-E).
> That includes the IHU, based on the NEC V53A processor, and the
> ARM-based payload processor that (I hope) will be designed by Lyle.
>
> I am also looking at using an open source operating system for the
> ground segment of the wide-band digital experiment.
>
> I would appreciate your candid comments on this as the project
> matures.


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