ARM Comparison

Whilst I haven't come across any direct comparisons of ARM Cortex based processors
there are a few things that I can point out that may be worthwhile considering before
taking the plunge...

If time is a major consideration, go with what your familiar with:,
If for example you are used to using Freescale 8Bit devices
then I would probably suggest sticking with Freescale as some people swear by the Codewarrior
IDE and the tools offered in that package. The same applies for other vendors favoured IDE's.

I would advise spending a little time with a few of the cheaper developement tools before
taking the plunge.

I can happily recommend the Olimex range of developement boards such as the STM32-P103STM32-P103
as these tend to be very cleanly layed out and all non power/ clock pins are generally available.
They are however not supplied with any software or documentation in the box, but a quick browse of the
vendors website will quickly resolve that in most cases. The downside is that there is no JTAG interface included.
So you would need to purchase this as a seperate item.

The LM3S9B90 Stellaris Eval kit, is a nice peice of hadware that comes with a FTDI based JTAG tool that can be used to
program and debug almost any Cortex device using the OpenOCD software debugger. Again a very nicely layed out board and
as this device has onboard ethernet it is supplied with the magnetics, unfortunatley I haven't had that much time to play
with this kit but it is looking very promising.

Most Cortex based applications can be developed using a variety of IDE's,
simply because manufacturers are releasing library packages for the IC's peripherals.
Many of the free unrestricted compilers are based upon the GNU Tools( gcc, make, etc.)
so with a little investment of time it is possible to configure a system to compile for multiple
targets without too much time spent learning an IDE.

It is the peripherals and thier libraries in my mind that are the differentiator.
To help you further a little more information on your intended application or
just the types of peripherals you need, power requirements etc.

Just a quick addition, here is a nice comparison by Keil for a number of Cortex M3 devices....

http://www.keil.com/boards/cortexm.asp

Whilst I haven't come across any direct comparisons of ARM Cortex based processors
there are a few things that I can point out that may be worthwhile considering before
taking the plunge...

If time is a major consideration, go with what your familiar with:,
If for example you are used to using Freescale 8Bit devices
then I would probably suggest sticking with Freescale as some people swear by the Codewarrior
IDE and the tools offered in that package. The same applies for other vendors favoured IDE's.

I would advise spending a little time with a few of the cheaper developement tools before
taking the plunge.

I can happily recommend the Olimex range of developement boards such as the STM32-P103STM32-P103
as these tend to be very cleanly layed out and all non power/ clock pins are generally available.
They are however not supplied with any software or documentation in the box, but a quick browse of the
vendors website will quickly resolve that in most cases. The downside is that there is no JTAG interface included.
So you would need to purchase this as a seperate item.

The LM3S9B90 Stellaris Eval kit, is a nice peice of hadware that comes with a FTDI based JTAG tool that can be used to
program and debug almost any Cortex device using the OpenOCD software debugger. Again a very nicely layed out board and
as this device has onboard ethernet it is supplied with the magnetics, unfortunatley I haven't had that much time to play
with this kit but it is looking very promising.

Most Cortex based applications can be developed using a variety of IDE's,
simply because manufacturers are releasing library packages for the IC's peripherals.
Many of the free unrestricted compilers are based upon the GNU Tools( gcc, make, etc.)
so with a little investment of time it is possible to configure a system to compile for multiple
targets without too much time spent learning an IDE.

It is the peripherals and thier libraries in my mind that are the differentiator.
To help you further a little more information on your intended application or
just the types of peripherals you need, power requirements etc.

Just a quick addition, here is a nice comparison by Keil for a number of Cortex M3 devices....

http://www.keil.com/boards/cortexm.asp

Hi Kelv,

I have been looking at some of the development boards and the link you provided is very useful.

Thanks,

DAB

Kelv,

As I said to Alistair, we are moving out of the stone age and our current vendor (Silabs) does not produce a an ARM based Mirco (as far as I know). So it is open season on IDE and dev board choice, Dev time is not as critical as being able to find a solution to replace the C8051 and maintain it.

According to the ARM website the is near a dozen vendors of the ARM Cortex family so I was trying to avoid reading 1000's of pages of manuals to try and find out the best micro to use. I had hoped that someone independent (as I have seen comparisons by some vendors, which will surly be biased) had made a comparison, or at the vary least a guide of what to watch out for.

How do people here choose their processors?

Thanks,

Ross

You can't avoid a lot of reading if you want to make a good choice. You need to have some idea of the target applications and make a list of what is important out of things like:

low power, on chip Ethernet MAC, USB, high speed USB, high speed USB phy on chip, fast IO, Ethernet phy on chip, good ADC, DACs, fast processing, floating point, etc etc .

Until you have that list, with at least rankings into must-haves and nice-to-haves you would be just guessing.

When you have a list of the parts you could use yhen you can start to think about cost of parts, cost of tools, future designs etc.

If it can be useful for you, I report my personal experience  to migrate from 8051 to ARM.  
 
I suggest you to  see in STM32 series. This old MCU family, respect other most recent and (Vendor declared) high performance offer the following. 
 
A great software support including: 
- a really complete and easy to learn / understand standard peripherals library, that after a initial learning effort, help to make operative any peripheral in 0 time. 
- use IDE tool that you prefer. All tool vendor support STM32, I suggest you Keil MDK in free 32K to evaluate the MCU performance, it include also a simulator to run and debug without any hardware, and it has a really efficient C compiler. 
-Hundred  and hundred of working firmware example in all embedded sector  ( Googling to see ..... )   
A wide choice of evaluation board, starting from the little STM32 Discovery board to the STM32 value linee evaluation board (also low-cost chinese clone available)  
 
If you like assembly language, expect also a 20-30 up boost gain in time 
For example  a my apps medium complexity original running on uPsd 3434 ( 8051 40Mhz/10 Mips) 42K pure assembly optimized, retarget for test on STM32 Discovery ( CortexM3 24Mhz) 28.5K code mixed C for control module / assembly for time critical routine, running about 23 time faster !!!    
 
I hope this is helpful for you.

Hi Ross,

Given the importance of your effort, I suggest that you first define the requirements for the applications in which your processor will go.  Then look at each candidate and rate them to how they meet your requirements, not how they stack up against each other.  When you get done, you should have a good clear reason for choosing one over the other.

If you use this type of selection process you can always get to what you need, verses selecting something that looks good.  A lot of time people end up choosing something that is mostly overkill for their applications and that approach can be costly.  Look at your future needs, cost of development, firmware development costs, reuse, maintenance and product obsolesence.  Just because the 8051 is old technology does not make it the wrong choice for you product.

Remember, Keep It Simple!

Thanks,

DAB

Hi,Rbuick

Firstly you need confirm which function you have used in Silabs Mcu

Secondly you need count on # I/O and How to work

Finally you can find same function ARM

It is not easy to transfer assembler to ARM,so I suggest You can use C language to design .

thanks

kemmi

@Michael, I have a general list of requirements, but my intention was not for the community to do my chip section but to try and simplify the process by finding some form of comparison that would allow me to refine the selection process (e.g. table listing peripherals specifications of ALL of the vendors products, indication of the pros/cons of each sub family etc.)

@Alessandro, Thanks for sharing your experiences, I had use a STM32 dev kit and found the lack of quick start information frustrating (as did others online), based what you said I will certainly have another look at it.

@DAB, I possibly was a bit rash in my comments about the C8051. I agree with you that the C8051 has its place, our application has evolved over the last 8 years to a point where the 8051 we are using is bursting at the seams and we would like to add a few more features. Hence look at ARM products.

@Chalie, so true, been caught on that one a couple of times, always read the release notes!

@Kemmi, code migration issues is less of a problem as we intend abandoning the current code and start afresh with C.

On the whole I think the message is get in there and start reading data sheets.

I think if you choose MDK-ARM tool chain from Keil then you will be able to scale your application quite easily.

The tool chain allows for development of ARM7, ARM9, Cortex M0, Cortex M3 from pretty much all the  major vendors with one simple IDE and compiler.

This means you can train yourself up on the tool chain and chop and change between manufacturers devices without the need to repurchase a new tool chain each time.

The tool is the same for all devices, and the only thing you will need to learn are the peripherals on that particular device.

For NXP and ST you will find a range of device libraries that ease the software development on the peripherals with example code for each peripheral.

MDK-ARM is also called the RealView tool suite and is available to down load off the ARM/Keil website.

There is a code restriction on the tool to 32k bytes but other than that it is full feature.

The full tool suite costs about £3k and is available to purchase from Hitex.

http://www.hitex.co.uk/index.php?id=2681

The Keil tool suite is effectively the official tool chain for ARM devices as Keil are owned by ARM. ARM do however support other tool chains such as IAR and GNU so if you have a history with either of these then perhaps this is a better route.

The licensing models for MDK-ARM have changed recently and you can purchase a professional version which now includes support for Ethernet, TCP-IP, email, USB, File Systems etc.

For new designs I suggest you start with Cortex M series cores as they are cheaper and better than the legacy ARM7/9 devices. You can debug with a simulator or via a debugging adapter.

The debugging adapter include ULINK-ME, ULINK2, and ULINK-PRO.

The ULINK-PRO allows for trace debugging.

Best Regards

David Giles

dgiles@hitex.co.uk<mailto:dgiles@hitex.co.uk