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Question about which tools to use, bugs, the best way to implement a function, etc should go here. Don't forget to see if your question is answered in the wiki first! When in doubt post here.
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jal
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Post by jal »

Colonel Kernel wrote:Application code may be in ROM, but the data is still in RAM. Without some means of protection apps can crap all over each other's heaps and stacks.
True, but in embedded systems there's usually only one app running. For concurrency, protothreads and the like are used, your classical OS view needs to be adjusted for embedded systems. Take a look at Contiki OS for example.


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Solar
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Post by Solar »

jal wrote:
Solar wrote:it can become quite an issue on low-powered devices (like Amigas then, or embedded systems today).
Of course, almost all current embedded devices you can actually run an OS on are superior in terms of processor power to an 68000.
The majority of all embedded-devices CPUs is 8-bit, and before you answer that you cannot run an OS on a 8-bit device, think twice or the Great Old Ones will bite your head off. ;-)
Every good solution is obvious once you've found it.
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Post by AJ »

Example of the above: I use 8 bit Atmel AVR's with 4KiB of flash memory and run my own multitasking OS on them.

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Post by jal »

Solar wrote:The majority of all embedded-devices CPUs is 8-bit, and before you answer that you cannot run an OS on a 8-bit device, think twice or the Great Old Ones will bite your head off. ;-)
I wasn't going to suggest that at all, of course :).


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Post by jal »

AJ wrote:Example of the above: I use 8 bit Atmel AVR's with 4KiB of flash memory and run my own multitasking OS on them.
That's quite cool. What do you use them for?


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Post by AJ »

At the moment, I've strung two Mega 128 AVR's together and am working on a networked hard drive MP3 player for my separates stereo system (just for fun!).

It's something that keeps going on the back-burner whenever I don't have enough time, but I have the basic hard disk reading, RS-232 (I'd like to go USB), input and display software up and running. I've had some difficulty sourcing a single-component MP3/WMA decoder and DAC here in the UK though - everyone wants to sell me 1000 units at a time :cry: . The other thing holding me back is my atrocious soldering skills!

Although multitasking isn't a requirement, it should provide for smoother menu surfing (only a cheap 2 line LCD display!) when playback is happening.

Cheers,
Adam

[Edit] Sorry - I meant 4KiB of RAM above, not flash memory - the Mega 128 has 128KiB of flash memory and an additional 4KiB of EEPROM[/Edit]
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Dex
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Post by Dex »

AJ wrote:At the moment, I've strung two Mega 128 AVR's together and am working on a networked hard drive MP3 player for my separates stereo system (just for fun!).

It's something that keeps going on the back-burner whenever I don't have enough time, but I have the basic hard disk reading, RS-232 (I'd like to go USB), input and display software up and running. I've had some difficulty sourcing a single-component MP3/WMA decoder and DAC here in the UK though - everyone wants to sell me 1000 units at a time :cry: . The other thing holding me back is my atrocious soldering skills!

Although multitasking isn't a requirement, it should provide for smoother menu surfing (only a cheap 2 line LCD display!) when playback is happening.

Cheers,
Adam
I live in UK and use one of these
http://apple.clickandbuild.com/cnb/shop ... tle=VMUSIC
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AJ
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Post by AJ »

Thanks, Dex! Page bookmarked :)

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Post by JackScott »

The other option is to visit manufacturer's websites and ask for samples. Most will give them out if you give them some sort of reason that you are developing a product and may buy more in future.

Sneaky, but sometimes it isn't far off the truth.
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Post by AJ »

To continue the thread hijack, if anyone is interested to see how multitasking works in an unpaged 8-bit uC, have a look at this link which is where I first learned about MT on AVR's.

It's useful even just to see what a massive architecture difference you have to take in to account on modern CPU's if you want your OS to be portable!

Cheers,
Adam
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