Subject:
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Re: Memory, Motors and Odd Things
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Thu, 11 Dec 2003 00:34:13 GMT
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Viewed:
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3791 times
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In lugnet.robotics.rcx.legos, Steve Hassenplug wrote:
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I ran into something odd, and I’m wondering if someone can explain it.
I have a pretty large BrickOS program, (the .lx is about 9k) and it uses
around 2k for variables. (I think)
I’ve noticed when the program is running, it’s not doing anything with the
motors, but they seem to buzz. I hooked up some diodes and lights, and found
the outputs are going both + and -.
I assume my variables are writing into the motor control area of BrickOS. Is
that possible?
Is there something I can do to stop it?
Any other thoughts?
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Hi Steve,
Are you using BrickOS 0.2.6.10?
In earlier versions, it was possible for malloc() to return pointers to RAM in
the range [F010,FB7F], which was shared with the motor port controller.
Writing to this memory adversely affected the motors. The problem was somewhat
sporadic because malloc() would only return addresses in the problem range when
memory was low or fragmented. If you want to read more, check out this
thread.
What firmware downloader did you use to download BrickOS (i.e. the brickOS.srec
file, not the .lx file)?
Using firmdl3 is fine, but NQC and all but the latest version of BricxCC have a
problem downloading BrickOS to the RCX correctly. The symptom was “growling
motors”, even when no program was running. Read more
here.
If you’re using BrickOS 0.2.6.10 and firmdl3, then it’s possible you have a
stray pointer that is writing beyond the memory allocated to you.
If you have recursive code, your program could be overflowing your stack memory
and corrupting memory (unlikely, but I thought I’d mention it since I have a
hunch what your program is for... :-).
Or, there could be Yet Another BrickOS Motor Port Bug in the offing... ;-/
Mark
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Message has 1 Reply:
 | | Re: Memory, Motors and Odd Things
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| (...) no. Ok, that's my first problem. (...) hmm. yep. malloc()... (...) no, using the firmdl3. (...) Yes, it's recursive. And, I'm sure your hunch is right. (...) It sounds like it's the malloc() bug. I'm using 0.2.6.09 (?) I'm not going to switch (...) (21 years ago, 11-Dec-03, to lugnet.robotics.rcx.legos, FTX)
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Message is in Reply To:
| | Memory, Motors and Odd Things
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| I ran into something odd, and I'm wondering if someone can explain it. I have a pretty large BrickOS program, (the .lx is about 9k) and it uses around 2k for variables. (I think) I've noticed when the program is running, it's not doing anything with (...) (21 years ago, 10-Dec-03, to lugnet.robotics.rcx.legos)
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