Subject:
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Re: legOS ... really a stack question
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 2 Jan 1999 21:24:55 GMT
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Original-From:
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Ben Laurie <BEN@nomorespamALGROUP.CO.UK>
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Viewed:
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1292 times
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Rick Kimball wrote:
>
> I'm still having reliability problems with legOS when
> using the task management routines. However, I think
> the problem has more to do with the stack than the
> tm routines. I think the problem is related to the
> direct-motor routines and the entries in h8300.rcx file.
>
> I noticed that when I have more than a couple of
> tasks and one of them uses the direct-motor fuctions
> the program flakes out. Looking at the direct-motor.c
> I noticed that it uses the following asm instruction:
>
> mov.b r6l, @0xf0000:16
>
> I'm not an assembler language programmer, so correct me
> if I'm wrong. I'm assuming that this moves one byte from
> the low word of register 6 into address location 0xf000.
>
> Then I noticed that in the h8300.rcx file the stack
> starts at 0xfefc. I'm assuming this is the top of
> the stack and that it should grow downward towards the
> heap which ends at 0xcc00. Let's just ignore the stack
> and the heap colliding for now.
>
> If both of my assumptions above are correct won't the
> direct-motor routines stomp the stack.
>
> I changed the topram entry in my h8300.rcx to be 0xef00 instead
> of 0xfefc. This made the program run without any problems.
> Was I just lucky or are my assumptions correct?
Hmmm ... good point. 0xf000 is memory mapped I/O for the motors, IIRC.
Not sure whats above there, but I wouldn't be surprised to hear it isn't
a good place to store things. I'd guess that setting the stack to 0xeffe
should be equally good.
I'll have to see if that also cures my mysterious problems...
Cheers,
Ben.
--
"My grandfather once told me that there are two kinds of people: those
who work and those who take the credit. He told me to try to be in the
first group; there was less competition there."
- Indira Ghandi
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message has 1 Reply:
 | | Re: legOS ... really a stack question
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| (...) All off-chip accesses to f000 or higher are memory mapped to the motors. Because accesses to addresses above fb7f are all on-chip or invalid, the motors are effectively memory mapped to f000-fb7f. (...) What are your symptoms again? One (...) (25 years ago, 2-Jan-99, to lugnet.robotics)
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Message is in Reply To:
| | legOS ... really a stack question
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| I'm still having reliability problems with legOS when using the task management routines. However, I think the problem has more to do with the stack than the tm routines. I think the problem is related to the direct-motor routines and the entries in (...) (25 years ago, 2-Jan-99, to lugnet.robotics)
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