ARM7 vs PIC32

Started by roboticsbcn May 9, 2008
Hello,

Someone can make a comparison between the architectures of the ARM7 and
PIC32?

Thanks!

An Engineer's Guide to the LPC2100 Series

Hi,

> Someone can make a comparison between the architectures of the ARM7 and
> PIC32?

For all intents and purposes, they are the same. Minor wrinkles are that
ARM has predicated instructions and MIPS has more registers (hence context
switching can be slower). They both have compact instruction sets for
narrow flash and smaller programs (Thumb/MIPS16). Carry is difficult on
MIPS and MIPS will potentially abort on integer overflow. MIPS has delay
slots, ARM not.

Job done.

--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
CrossWorks for ARM, MSP430, AVR, MAXQ, and now Cortex-M3 processors

Finally!! Someone who can compare the difference between two MCUs without
getting religious.

Thanks Paul.

Cheers,

Peter.

Paul Curtis wrote:
> Hi,
>
>> Someone can make a comparison between the architectures of the ARM7 and
>> PIC32?
>
> For all intents and purposes, they are the same. Minor wrinkles are that
> ARM has predicated instructions and MIPS has more registers (hence context
> switching can be slower). They both have compact instruction sets for
> narrow flash and smaller programs (Thumb/MIPS16). Carry is difficult on
> MIPS and MIPS will potentially abort on integer overflow. MIPS has delay
> slots, ARM not.
>
> Job done.
>
> --
> Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
> CrossWorks for ARM, MSP430, AVR, MAXQ, and now Cortex-M3 processors
>
--- In l..., "roboticsbcn" wrote:
>
> Hello,
>
> Someone can make a comparison between the architectures of the ARM7 and
> PIC32?
>
> Thanks!
>
Hi,

lets not forget one critical value when comparing two CPUs, how many
clocks per instruction are needed in the average of a large program to
complete an instruction.

afaik, this value is 1.9 for an ARM7 but I could not find the number
for MIPS, it is either called something else or not easy to find.

ARM core has the reputation to be particular low in power consumption,
a reputation that the MIPS core does not share. However, I have seen
the AVR32 running a benchmark versus an ARM7 and the AVR easily beat
the ARM7, once again because it needed a lot less cycles to do the
same job.

I do like the ARM devices, not primarily for the great core but for
the availability of so many derivatives from all the vendors at very
good prices.

Just my 2 cents

Bob
On Sat, May 10, 2008 at 4:53 AM, roboticsbcn wrote:
> Someone can make a comparison between the architectures of the ARM7 and
> PIC32?
>

Paul Curtis talked about the architecture difference. For that they are actually
quite comparable hence "the same".

PIC32 is relatively new. So the support from 3rd party vendor is not so good
compated to ARM7.

C32 is based on GCC. But there are no free GNU toolchain for PIC32 yet
due to the fact that nobody has created a C library for PIC32. The compiler
itself is free.
Reference: http://forum.microchip.com/tm.aspx?m)2995

There are also more types of AMR7 device from more vendors. So ARM7
does have an edge on this. The migration path for ARM7 may also be
better since you have Cortex M3 and AEM9 types of MCU to go to if
you want to switch.

PIC32 is only from Microchip and it is very new. Microchip does have
good reputation in terms of keeping the parts for very long time and the
support is quite good.

In the end, I think now ARM7 is better than PIC32 for many end users.
Let's wait and see if PIC32 can be a real success in the industry.
I think it will be a moderate success but ARM7/Cortex M3 will have
much more market shares.

An interesting interview here of Microchip CEO.

***************************************
http://www.eetimes.com/news/semi/showArticle.jhtml?articleID 7404231
EE Times: Recently, Microchip entered the 32-bit MCU market. Why?

Sanghi: The problem is that when a customer is looking at a competitor's 32-bit
solution, [to win that customer] we [also] need a 32-bit solution.
Once we're in,
we can see what the customer's needs are and what they are trying to do.
More often than not, we're able to show them how the most cost-effective
solution is to use our 16-bit solution. So, we're able to win a large number of
design wins with 16 bit. [But we're invited in] because we have a
32-bit product.
That's doesn't mean we're not getting design wins at 32 bits.
***************************************

So you can see even he is not that confident about the PIC32.

Xiaofan (just start with PIC32 and learning more ARM7)
http://mcuee.blogspot.com

Bob,

> > Someone can make a comparison between the architectures of the ARM7
> and
> > PIC32?
> >
> > Thanks!
> >
> Hi,
>
> lets not forget one critical value when comparing two CPUs, how many
> clocks per instruction are needed in the average of a large program to
> complete an instruction.
>
> afaik, this value is 1.9 for an ARM7 but I could not find the number
> for MIPS, it is either called something else or not easy to find.
>
> ARM core has the reputation to be particular low in power consumption,
> a reputation that the MIPS core does not share. However, I have seen
> the AVR32 running a benchmark versus an ARM7 and the AVR easily beat
> the ARM7, once again because it needed a lot less cycles to do the
> same job.
>
> I do like the ARM devices, not primarily for the great core but for
> the availability of so many derivatives from all the vendors at very
> good prices.

None of that is a comparison of architecture. That's comparing
implementation. As for AVR32 vs ARM7, um, like looking at an ARM in the
mirror. It's hardly an earth-shattering architecture, unlike the ARM
architecture when it came out. Again, comparing some AVR32 to some ARM7 is
comparing implementation, not architecture. Sure, the architecture might
help things along a bit, but implementation is also key.

--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
CrossWorks for ARM, MSP430, AVR, MAXQ, and now Cortex-M3 processors

>An interesting interview here of Microchip CEO.
>
>***************************************
>http://www.eetimes.com/news/semi/showArticle.jhtml?articleID 7404231
>EE Times: Recently, Microchip entered the 32-bit MCU market. Why?
>
>Sanghi: The problem is that when a customer is looking at a competitor's 32-bit
>solution, [to win that customer] we [also] need a 32-bit solution.
>Once we're in,
>we can see what the customer's needs are and what they are trying to do.
>More often than not, we're able to show them how the most cost-effective
>solution is to use our 16-bit solution. So, we're able to win a large number of
>design wins with 16 bit. [But we're invited in] because we have a
>32-bit product.
>That's doesn't mean we're not getting design wins at 32 bits.
>***************************************

When I see statements like that I wonder how many customers really know so little about their
requirements, and are unable to do their own research, that they have to have the manufacturer come
and hold their hand....
Maybe it's just the ones where Marketing decides on what parts to use and then the engineers get
stuck with whatever they decide, even if it isn't the best technical solution...
I've worked at one company where the purchasing department made the
decision...

On Sat, May 10, 2008 at 4:25 AM, Mike Harrison wrote:

> [sbip]
>
> When I see statements like that I wonder how many customers really know so
> little about their requirements, and are unable to do their own research,
> that they have to have the manufacturer come and hold their hand....
>
>
> Maybe it's just the ones where Marketing decides on what parts to use and
> then the engineers get stuck with whatever they decide, even if it isn't the
> best technical solution...
>

> When I see statements like

You have to look at the history of the Microchip marketing to know why that
was said. It has nothing to do with confidence.

> that I wonder how many customers
> really know so little about their
> requirements,

LOL - you should read some of the emails I get.

Regards,
Richard.

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> Someone can make a comparison
> between the architectures of the ARM7 and
> PIC32?

One observation.

Many students around the world learn about computer architecture via the
book:

Patterson, D.A. and Hennessy, J.L. (2004) "Computer Organization and Design:
The Hardware / Software Interface", (3rd Edition). Elsevier /
Morgan-Kaufmann. ISBN: 1-55860-604-1.

The "PH" book describes the MIPS I architecture. Not quite the same as that
employed in PIC32, but the same heritage. It may be that there are
thousands of graduate developers in the world who have the skills needed to
understand the way that the PIC32 operates ...?

I suspect that this is not the case with ARM (I may be wrong)

Michael.