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'[EE] The MMU Dilemma'
2009\06\11@214614 by solarwind

picon face
On Fri, Jun 12, 2009 at 2:43 AM, solarwind<spam_OUTx.solarwind.xTakeThisOuTspamgmail.com> wrote:
> Hey all!
>
> I'm in search for the perfect microcontroller that can run QNX. I
> would normally be ok and settle with ucLinux, but unfortunately, it's
> not a real-time OS by nature. So I need QNX. The trouble with QNX is
> that it requires an MMU. Out of all the architectures it supports, I
> think the ARM architecture is the most suitable for my purposes (low
> power, easy to use, inexpensive), but I could be wrong. The lowest end
> ARM chips that support an MMU is the ARM 922T (I think). The trouble
> with this is that it has over 200 pins and requires external RAM and
> Flash and so on.
>
> My question: do any of you know of a microcontroller or a cheap
> system-on-chip that is:
> - relatively low cost
> - lowest pin count possible
> - has an MMU, can therefore support QNX
> - not too complicated to use, that is, a hobbyist can work with it

Whoops, I forgot to add

- low power consumption

to the list. Low power is very important to me as I'll be making stuff
that will run off of solar panels/small wind generator.

Thank you!

2009\06\11@222429 by Xiaofan Chen

face picon face
On Fri, Jun 12, 2009 at 9:45 AM, solarwind<.....x.solarwind.xKILLspamspam@spam@gmail.com> wrote:
>> My question: do any of you know of a microcontroller or a cheap
>> system-on-chip that is:
>> - relatively low cost
>> - lowest pin count possible
>> - has an MMU, can therefore support QNX
>> - not too complicated to use, that is, a hobbyist can work with it
>
> Whoops, I forgot to add
>
> - low power consumption
>
> to the list. Low power is very important to me as I'll be making stuff
> that will run off of solar panels/small wind generator.

According to the wiki, none of the chips supported by current
QNX are small and easy to handle by hobbyists unless you are
willing to fork out some money to buy the ready made boards.

http://en.wikipedia.org/wiki/QNX
http://community.qnx.com/sf/wiki/do/viewPage/projects.bsp/wiki/BSPAndDrivers


--
Xiaofan http://mcuee.blogspot.com

2009\06\11@222714 by Xiaofan Chen

face picon face
On Fri, Jun 12, 2009 at 9:45 AM, solarwind<x.solarwind.xspamKILLspamgmail.com> wrote:
>> I'm in search for the perfect microcontroller that can run QNX. I
>> would normally be ok and settle with ucLinux, but unfortunately, it's
>> not a real-time OS by nature. So I need QNX. The trouble with QNX is
>> that it requires an MMU.

What kind of real-time performance you need? Why do you think
you need QNX and not other smaller RTOS (uCOS-II, FreeRTOS,
ThreadX, eCOS, etc)?

Even the chips which can run uCLinux are not small. At least
none of the current Microchip MCUs can run uCLinux.

--
Xiaofan http://mcuee.blogspot.com

2009\06\11@223632 by solarwind

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On Fri, Jun 12, 2009 at 3:27 AM, Xiaofan Chen<.....xiaofancKILLspamspam.....gmail.com> wrote:
> What kind of real-time performance you need? Why do you think
> you need QNX and not other smaller RTOS (uCOS-II, FreeRTOS,
> ThreadX, eCOS, etc)?

You have a point there. FreeRTOS is the only one out of those which
I'll consider.

> Even the chips which can run uCLinux are not small. At least
> none of the current Microchip MCUs can run uCLinux.

True, but ARM7 can run ucLinux and those are relatively small (64
TQFP). Cortex M3 can also run Linux and I think a certain company
makes DIP sized cortex M3.

2009\06\11@225103 by Xiaofan Chen

face picon face
On Fri, Jun 12, 2009 at 10:36 AM, solarwind<EraseMEx.solarwind.xspam_OUTspamTakeThisOuTgmail.com> wrote:

>> Even the chips which can run uCLinux are not small. At least
>> none of the current Microchip MCUs can run uCLinux.
>
> True, but ARM7 can run ucLinux and those are relatively small (64
> TQFP). Cortex M3 can also run Linux and I think a certain company
> makes DIP sized cortex M3.

Luminary makes some small Cortex M3 chips but the DIP sized
Cortex M3 can not run uCLinux due to lack of Flash/RAMs
and lack of expansion capability. I believe only very big
Cortex M3s can run uCLinux.

Typical small ARM7 MCUs can not run uCLinux either due to
the same reason.

--
Xiaofan http://mcuee.blogspot.com

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