--- Em dom, 21/9/08, Walter Banks <walter@bytecraft.com> escreveu:

> I couldn't get your link to open but am interested in
> seeing your approach.

I think the files area on yahoogroups.com are not accessible for non-member=
s. If you want, I may send the files directly to your e-mail address.

> For PIC12 and PIC16 the type of applications that are
> implemented
> can usually be implemented used compile time re-use of RAM
> space.
> This is even more so in applications that are implemented
> as event
> driven run to completion applications whose RAM
> requirements
> are both predictable and typically less. (Response time
> average is
> better fastest is lower that other approaches.)
> =

> Some of the PIC18 applications can benefit from dynamic
> memory
> allocation.
> =

> Most embedded real time allocations do not want dynamic
> memory allocation because failure often affects more of the
> application functionality than the alternatives. (Just ask
> the anti lock brake systems that were failing in the mid
> 80's
> if dynamic allocation is a good idea)
> =

> Walter..

I agree, but sometimes it simplifies things.
I don't use dynamic allocation for critical parts, but FreeRTOS needs it.

I wrote a multi-thread application where just one thread have access to kay=
board and LCD. The other threads send messages to the interface thread, by =
allocating memory and filling it with the message, then passing a pointer t=
hrough a queue. The interface thread shows the message and frees the memory.

If there is no free memory, the thread that wants to send a message just wa=
its, or if the message is not critical, just skip it.

To avoid the fragmentation problem, all messages have a maximum length (the=
 LCD shows only 32 chars anyway) and the threads allocate always the same a=
mount of memory for the messages.

Regards,

Isaac


      Novos endere=E7os, o Yahoo! que voc=EA conhece. Crie um email novo co=
m a sua cara @ymail.com ou @rocketmail.com.
http://br.new.mail.yahoo.com/addresses

-- =

http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist