Re: AVR or PIC for a beginner
- From: "rickman" <gnuarm@xxxxxxxxx>
- Date: 21 Feb 2007 06:22:54 -0800
On Feb 19, 1:32 pm, "linnix" <m...@xxxxxxxxxxxxxxxxxx> wrote:
* For small projects I look at how familiar I am with the chip,
because it takes time to spin up on a new architecture. For
large projects I figure that the time to learn the new
architecture and the expense of new tools will be paid back
in efficiency as time goes on -- this is obviously a judgment
call, and one that should be made carefully.
If it's my choice, I pick the micro and ask for additional money for
different micro. For example:
1. Arm (cost)
2. Avr (cost + 100)
3. Freescale (cost + 300)
4. MSP (cost + 500)
5. PIC (cost + 1000)
I will do any micro with the right price. Otherwise, I prefer ARM M3
Cortex nowaday, except for very low power and code density with AVR.
ARM M3 is around 30% higher in power and 40% higher in code space than
AVR, but a non-issue most of the time.
The LMI chips meet most of what I need, except for the relatively new
company. TI and ST are coming on-line with M3 soon. Hopefully, they
will have parts close enough to LMI.
A lot of people seem to think that the ARM 32 bit MCUs have some power
disadvantage compared to the 8 bit MCUs. I have not seen it myself.
The CM3 devices from Luminary Micro are not as low power, but then
they are the first generation.
I have looked at the AVRs and many of the other processors and, other
than the sleep mode where some individual parts are highly optimized,
the SAM7 and LPC2xxx parts are neck and neck with nearly all 8 bit
parts. The SAM7 parts are about 0.5 mA/MHz even while running at full
speed with parallel I/O, UART, SPI and TWI all running. That is about
the same power consumption as the 8 bit parts.
Another thing I consider a red herring is code density. I don't care
if one processor uses 40% more Flash space. I just care that I can
make my app fit in a given part at a given price. The SAM7 parts are
cheaper than the AVR parts at a given Flash size, so even if I have to
bump up to the next size flash it is still a break even on price.
With the SAM7 parts reaching 512 KB of Flash, I don't see Flash size
being a limitation compared to any of the 8 bit parts.
So why consider a 8 bit MCU at all at this point unless there is some
peculiar need that the ARMs can't satisfy? For general processing,
including power constrained processing apps, the ARMs are pretty hard
to beat.
.
- References:
- AVR or PIC for a beginner
- From: [Frank]
- Re: AVR or PIC for a beginner
- From: Tim Wescott
- Re: AVR or PIC for a beginner
- From: linnix
- AVR or PIC for a beginner
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