Re: RTOS's and Windows CE question
From: Dave Hansen (iddw_at_hotmail.com)
Date: 09/09/04
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Date: Thu, 09 Sep 2004 14:32:32 GMT
On Thu, 9 Sep 2004 14:39:10 +0200, "David Brown"
<david@no.westcontrol.spam.com> wrote:
>
>"Mike Harding" <mike_harding@nixspam.fastmail.fm> wrote in message
>news:dlp1k0581uf4g6794fs5ejc3s614cqjtt6@4ax.com...
[...]
>> The product will be truly embedded having no display
>> capability, but will contain both an ethernet port, and a
>> USB port, to allow for customer configuration etc.
>> Although the product has no 'hard' real-time requirement,
>> the worst case response times should be less than one or
>> two milliseconds, under all operating conditions (that
>> includes ethernet activity).
>>
>
>You have specified a minimum worst case response time - that is precisely
>what real-time means. To my knowledge, CE is not real-time, although most
>versions are what is termed "soft real-time", meaning that it probably will
I evaluated WinCE for a project at a PPOE about 5 years ago. At the
time, WinCE 2.x was acknowledged by Microsoft to be less than a hard
real-time OS, but the forthcoming (at the time) WinCE 3 was going to
be truely real-time.
We didn't use it because it wasn't the best fit, but we probably could
have without undue difficulty.
>respond fast enough, but there are no guarentees. Whether that is good
>enough or not depends on what might happen if a response takes longer than 2
>msecs once in a while.
>
>CE is an appropriate choice where you want to build a small device that
>looks like windows, and can run pretend-windows applications like pocket
>word processors. If you don't have a screen, or don't need to run
>ready-made CE applications, then it has no advantages over other systems,
>and plenty of disadvantages (cost, large footprint, lack of source code,
>poor reputation).
>From what I remember WinCE would be ideal in an environment with a
graphical display and user interaction, especially if your programmers
are familiar with the Win32 API. It's getting some use in telematics.
It doesn't sound like an exceptionally good fit for the OP's project.
>
>Alteratives to look at are qnx, linux (available with hard real-time
>varients if needed), eCos, RTEMS, vxWorks, microC OS 2.
I'll second QNX because I like the architecture, and I've actually
used it. I've looked at RTEMS, but the project I intended to use it
on got cancelled. I've not used eCos, or even looked at it, but it
sounds like a better choice than Linux. I evaluated VxWorks for
another project (back when Tornado was new) and rejected it because
the tools were too buggy to be useful. The OS itself looked OK.
Micro C/OS might be too lightweight.
The USB requirement might be the kicker. If you have to have USB, the
OS which handles that best is probably the best choice. Just about
everyone gets TCP/IP right (or close to right) these days.
Regards,
-=Dave
-- Change is inevitable, progress is not.
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