PIC vs AVR vs ARM

Started by Miem October 2, 2006
Hi All,

As an amateur embedded circuit player, I have used couple of AVR and
PIC microcontrollers in the past.

In these days it is not to hard to find small, ARM based ready to use
embedded  boards under $100. They seems to have faster clock speed then
most of the AVR and PIC boards.

Can anybody shortly compare ARM with PIC ad AVR interms of (a)
performance (b) software support (c) price?

Regards,

Miem

Miem wrote:

> Hi All, > > As an amateur embedded circuit player, I have used couple of AVR and > PIC microcontrollers in the past. > > In these days it is not to hard to find small, ARM based ready to use > embedded boards under $100. They seems to have faster clock speed then > most of the AVR and PIC boards. > > Can anybody shortly compare ARM with PIC ad AVR interms of (a) > performance (b) software support (c) price? > > Regards, > > Miem >
(a) Significantly better. You can't beat it with an 8-bit processor. (b) At least as good, particularly if you don't mind gnu tools. (c) It'll be harder to really shave the pennies off in a high- volume application, and a bare-minimum ARM board will be bigger, more power hungry and have a higher BOM cost than a bare- minimum AVR or PIC board. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/ "Applied Control Theory for Embedded Systems" came out in April. See details at http://www.wescottdesign.com/actfes/actfes.html
> ... > (c) It'll be harder to really shave the pennies off in a high- > volume application, and a bare-minimum ARM board will be bigger, > more power hungry and have a higher BOM cost than a bare- > minimum AVR or PIC board.
AVR has wider operating voltage range than ARM, which is useful for dealing with different logic devices.
linnix wrote:
> > ... > > (c) It'll be harder to really shave the pennies off in a high- > > volume application, and a bare-minimum ARM board will be bigger, > > more power hungry and have a higher BOM cost than a bare- > > minimum AVR or PIC board. > > AVR has wider operating voltage range than ARM, which is useful for > dealing with different logic devices.
The only technical downsides to ARM are the minimum system complexity and power, as Tim already mentioned. As always in engineering, it comes down to 'it depends' and the dependency is, in this case, what you need (or want) to achieve with the system. If you need an ultra low current system monitor, it's hard to beat the AVR or PIC (I prefer the AVR for a number of reasons). So which is 'better' is a much harder question. Cheers PeteS
PeteS wrote:
> linnix wrote: >>> ... >>> (c) It'll be harder to really shave the pennies off in a high- >>> volume application, and a bare-minimum ARM board will be >>> bigger, more power hungry and have a higher BOM cost than a >>> bare- minimum AVR or PIC board. >> >> AVR has wider operating voltage range than ARM, which is useful for >> dealing with different logic devices. > > The only technical downsides to ARM are the minimum system complexity > and power, as Tim already mentioned. As always in engineering, it > comes down to 'it depends' and the dependency is, in this case, what > you need (or want) to achieve with the system. > > If you need an ultra low current system monitor, it's hard to beat the > AVR or PIC (I prefer the AVR for a number of reasons). So which is > 'better' is a much harder question. >
Some more things that come to mind... Size of package could be an issue as well. Not a lot of ARM options below 48 pins. Almost all ARM have JTAG so if you need OCD you lose multiple pins. Determinism when toggling I/O ports could be an issue. The ARM has to pass through a number of interfaces before the I/O pin is reached, and this can take some clock cycles and add jitter. This of course allows an AVR to run at lower clock frequqncy at the same toggle rate. Putting the I/O on the 32 bit ASB/AHB bus will help but the drawback is higher capacitance on the ASB/AHB bus which should increase power consumption. ARM parts typically lack byte addressable EEPROM. It is easy to prototype using DIL packages. Normally not available for ARM. The AVR has more (but narrower) registers allowing global variables to be stored there. Bit instructions. Generally AVR code is smaller than ARM code.
> Cheers > > PeteS
-- Best Regards, Ulf Samuelsson ulf@a-t-m-e-l.com This message is intended to be my own personal view and it may or may not be shared by my employer Atmel Nordic AB
> Almost all ARM have JTAG so if you need OCD you lose multiple pins.
That is the positive side of ARM. Jtag is always there, and reliable. AVR Jtag, on the other hand, could be disabled, and thus un-reliable by definition.
On 2 Oct 2006 15:16:16 -0700, "linnix" <me@linnix.info-for.us> wrote:

>> Almost all ARM have JTAG so if you need OCD you lose multiple pins. > >That is the positive side of ARM. Jtag is always there, and reliable. >AVR Jtag, on the other hand, could be disabled, and thus un-reliable by >definition.
Last I looked, some years ago, ARM JTAG is also documented -- including the debug interface. Jon
Miem wrote:
> Hi All, > > As an amateur embedded circuit player, I have used couple of AVR and > PIC microcontrollers in the past. > > In these days it is not to hard to find small, ARM based ready to use > embedded boards under $100. They seems to have faster clock speed then > most of the AVR and PIC boards. > > Can anybody shortly compare ARM with PIC ad AVR interms of (a) > performance (b) software support (c) price? > > Regards, > > Miem
AVR and PIC aren't really comparable with ARM, the first two are very low cost/power 8 bit machines, the ARM is a higher power, higher cost 32 bit machine. If you need to make a device that needs to run on a coin cell for 2 years, you can't pick an ARM processor, if you need a CPU that can do real time FFT, a PIC won't do it.
steve <bungalow_steve@yahoo.com> wrote:

> AVR and PIC aren't really comparable with ARM, the first two are very > low cost/power 8 bit machines, the ARM is a higher power, higher cost > 32 bit machine. If you need to make a device that needs to run on a > coin cell for 2 years, you can't pick an ARM processor, if you need a > CPU that can do real time FFT, a PIC won't do it.
I thought so too, but the products from luminary micro (luminarymicro.com), discussed in this newsgroup recently and in Circuit Cellar, have changed my mind. They make ARM CPUs with very little RAM and flash, on the cheap.... they say less than one dollar in 10k quantities (from an advertising spiel) ttyl, --buddy
Buddy Smith wrote:

> I thought so too, but the products from luminary micro > (luminarymicro.com), discussed in this newsgroup recently and in Circuit > Cellar, have changed my mind. > > They make ARM CPUs with very little RAM and flash, on the cheap.... they > say less than one dollar in 10k quantities (from an advertising spiel) > > ttyl, > > --buddy
yes but they are very high power, I think 10x the power of the AVR at 1Mhz, if I remember correctly