Re: PIC vs AVR vs ARM

"rickman" <gnuarm@xxxxxxxxx> skrev i meddelandet
news:1159903397.463883.11040@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
We have used AVR MCUs in many of our products and were very happy with
them. On a new project I decided to take a look at the ARM MCUs to see
if we could branch out from some of the limitations of the AVR. We did
a very exhaustive comparison between the various ARM processors and the
ATmega128 and found that the ARM chips were generally lower power,
lower cost and fit in a smaller footprint on the board. We also were
able to use a much smaller crystal.

When power is an issue, you typically have to spend as much
time as possible in sleep mode, and the Picopower AVR
will be at least an order of magnitude better than the AT91SAM7 here.

Also, when running from an R/C oscillator you can turn on/off almost
instantly,
while the AT91SAM7 probably have to start the PLL which will take ~16 ms.
One drawback of Picopower is that the startup time from sleep
is increased from a few clock cycles to about 70 us.
This is the time it takes to activate the brownout detector which is
disabled in deep sleep.
(Don't worry, the part is protected from Brown-Out by the Power On Reset in
deep sleep)

I think the PicoPower AVR is therefore hard to beat when you really need low
power.

The ARM we chose for this project was the AT91SAM7S64 due to its
combination of low cost and low power. The Philips parts seem to run a
close second and may even beat the Atmel SAM7 parts depending on
exactly the combination of features you need. If you don't need the
lowest power then the other brands of ARM chips could be considered, ST
Micro STR7, TI TMS470 and Analog Devices ADuc7 among others.

Did you check out the feature comparison chart at www.gnuarm.com?
Click to the Resources page and scroll down to the ARM chips section
where you will find three different links for the comparison chart.






--
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



.

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