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question about ARM

Started by ramsin May 25, 2008
> So Cortex-M series (there is also an M1) are more like regular > single-stack micros.
More like, but not actually single stack. There are still two stacks. -- Regards, Richard. + http://www.FreeRTOS.org & http://www.FreeRTOS.org/shop 17 official architecture ports, more than 5000 downloads per month. + http://www.SafeRTOS.com Certified by T�V as meeting the requirements for safety related systems.
"Eric Smith" <eric@brouhaha.com> wrote in message 
news:m3r6bqyrc5.fsf@donnybrook.brouhaha.com...
> FreeRTOS.org wrote: >> The Cotex-M3 is designed from the ground up to be an embedded core and >> includes features that make it very easy to support using an RTOS. > > I thought it was just a Thumb-only ARM. What features did they add that > you've found useful for RTOS support?
Integrated interrupt controller, integrated SysTick, interrupt system that makes nesting very simple, PendSV mechanism to make nesting even simpler, fast interrupt entry - all these things make implementation and portability between vendors much simpler. Its a whole lot more than a Thumb only ARM7, if that is what you were implying. -- Regards, Richard. + http://www.FreeRTOS.org & http://www.FreeRTOS.org/shop 17 official architecture ports, more than 5000 downloads per month. + http://www.SafeRTOS.com Certified by T&#2013265948;V as meeting the requirements for safety related systems.
> 1. ARM is, i think, the most popular CPU core right now, > used in iPod and in many mobile phones.
Well that depends who you ask :o) Renesas will claim to sell more, and 8051 in all its shapes and forms as a collective still sells in huge numbers, then you have the blob micros that get used in things like very low cost toys that sell by the bucket full.
> 2. ARM has a very interesting design philosophy. its RISC > and also has conditional execution of ALL instructions.
This does not apply to the Cortex-M3, which does not have ARM mode but Thumb-2.
> it also has a Thumb mode. these are unique to the ARM.
Thumb mode is unique to ARM as it defines ARM instructions, but the idea of having a duel instruction set is not. I think MIPS can also run MIPS16, a 16bit version of the instruction set. -- Regards, Richard. + http://www.FreeRTOS.org & http://www.FreeRTOS.org/shop 17 official architecture ports, more than 5000 downloads per month. + http://www.SafeRTOS.com Certified by T&#2013265948;V as meeting the requirements for safety related systems.
"FreeRTOS.org" <noemail@given.com> wrote in message 
news:PHu_j.9435$DZ6.2543@text.news.virginmedia.com...
[snip]
> Thumb mode is unique to ARM as it defines ARM instructions, but the idea > of having a duel instruction set is not. I think MIPS can also run > MIPS16, a 16bit version of the instruction set.
So Thumb and ARM fight for control. Anybody know who won. Clearly Thumb for the Cortex-M series. Peter
"adsouzp" <adsouzp@gmail.com> skrev i meddelandet 
news:T6idnfCDTrXZ2qfVnZ2dnUVZ_iydnZ2d@giganews.com...
> hello: > >> I have chose ARM series but currently there are two different models > as: > > excellent choice. > > 1. ARM is, i think, the most popular CPU core right now, > used in iPod and in many mobile phones. > > 2. ARM has a very interesting design philosophy. its RISC > and also has conditional execution of ALL instructions. > it also has a Thumb mode. these are unique to the ARM. > > 3. its 32-bit in a small, inexpensive package so that you > can run uCLinux on it easily. >
If you want to run (uC)Linux, you will have to use external memory The linux-2.6.25 is close to 3,5 MB on an ARM... You are likely to want to to have SDRAM, so your "small, inexpensive" package becomes 150-200 pins. Then it does not make a lot of sense to go ARM7 nor Cortex-M/R families. Why waste time on uCLinux when you can get the real thing. The AT91SAM9XE will give you an ARM running up to 200 MIPS in TQFP. Pin compatible AT91SAM9G20 will provide 400 MIPS, but will require external memory. The MMU in the ARM926 core makes it possible to store several applications in the internal flash, and allows you to link both applications to the same address, while you store them at different addresses. This solves a significant problem, if you do field upgrade.
> so, if you learn ARM, you learn a new architecture and can > also install Linux on your simple MCU board. you learn Linux > also. > > this is the future and you will be prepared for the future! > have fun! > > Aaron >
-- Best Regards, Ulf Samuelsson This is intended to be my personal opinion which may, or may not be shared by my employer Atmel Nordic AB