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AdrianJ
Joined: 16 Jan 2006 Posts: 2483 Location: Queensland
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Posted: Thu Mar 07, 2013 6:41 am Post subject: |
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Agreed, but most 'multi-tasking' is in reality things like timing events, updating a display, reading switches or keypads, accepting and parsing serial messages, and generating other messages. These can easily be handled in an AVR so that a human sees all the tasks happening 'together', even though in fact they are all only sequential, through one processor.
I like Per's approach of assigning tasks in powers of 2 descending timing order. Never used it quite like that, but it sounds neat. Mostly I just use a counter, and count down, doing various things at different counter steps. _________________ Adrian Jansen
Computer language is a framework for creativity |
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Per Svensson
Joined: 03 Oct 2004 Posts: 235 Location: Gothenburg, Sweden
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Posted: Thu Mar 07, 2013 9:33 am Post subject: |
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I agree Hubert, and it would be wonderful if someone took his time (and skill) to write a true RTOS kernel for the Xmega.
There are of course numerous examples of this need. Motor controllers, Alarm systems, Human interfaces , ...
If one need handling asynchronous tasks on the microsecond level depends on the application type however.
If you need to respond to unexpected events this is true, but if you just need to run internal processes on exact and predetermined
intervals, a task-swapper is even better than an RTOS.
In most of my own application there are very few external events, other than UART, claiming asynchronous access. These can often
wait a few ms for service and are never a problem. Most other processes are initiated on predetermined timer events.
In my world, a missed task is however a disaster, so I need to know that high priority tasks are always executed, and started without time jitter.
What i want to say is that we need both types. A good task controller for synchronous tasks AND a good task swapper or RTOS for asynchronous tasks.
/P |
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hgrueneis
Joined: 04 Apr 2009 Posts: 902 Location: A-4786 Brunnenthal
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Posted: Thu Mar 07, 2013 5:14 pm Post subject: |
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Adrian and Per,
yes and yes.
Agreed to everything both of you say.
Just wanted to point out what to expect.
And you are also right that there is no single solution to all the tasks one wants it to handle.
One step closer would be ARM but overkill for most.
For my own use I would like a micro controller chip that can resolve picoseconds (one is never satisfied).
Maybe with the next generation we get optical chips?
Hubert |
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olhexy
Joined: 03 Apr 2011 Posts: 192 Location: Tilburg, Netherlands
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