Niklas Wennerstrand wrote:

> I have stumble on a pdf file on the new Microchip CD-ROM under Download\lit\tr
uth.pdf
> This is a comparison between the AVR and the PIC if any one is interested.
> Regards
> Niklas

I've read it, it's a very misleading  document.   The very fact of it's existenc
e
indicates that uChip consider Atmel to be a major threat.

I just looked at again and now that I have actually worked with the Mega, 1200,
2313,
8515, 8535 and 8533, I can tell you from experience that most of the above "TRUT
H.PDF" is
absolute male bovine fecal matter.

There is repeated mention of Atmel's usage of No of bytes to indicate size of pr
ogram
memory and those who have not grasped the basic concept that all AVR instruction
s are 16
bit multiples might be missled (for example) by Atmel's true claim for the AT90S
1200 of
1k bytes program memory.

If you do not appreciate the above difference then it is easy to underspecify re
quired
memory for doing a job with Atmel AVR parts.

As an example I used a '1200 to engineer an eight channel PWM controler with cus
tom bit
banged serial protocol and reprogrammable network I.D.  The code just fit and th
e '1200
was just fast enough running with a 4mHz xtal.   Using 16F84s I would have had p
lenty of
code space but spent almost twice as much for the uC, had to run it at 10MHz and
 still
probably required 4 x 16F84s to control the same No of channels due to a much lo
wer
effective speed of instruction execution relative to clock speed.

If you need to use more than the 32 bytes (Number of cache accumulators on the A
VR) then
your program will start to use program memory at a higher rate due to the extra
overhead
but then.... PIC bank swapping, INDF addressing etc required to control I/O etc
is just
as bad if not worse.   The large No of vectored interupts in conjunction with 32
 cache
accumulators means that you can customise a rapid interupt system such as the Z8
0's
shadow registers.   Addressable push/pop stack on all but the '1200 give flexibi
lity as
do many special addressing instructions.

Down side is that the Atmel free assembler is very rudimentary (ie not allowing
nested
macros or conditional directives)

I suggest you invest an Atmel STK200 kit (cheap) and start reaping the benefits,
 Last
project I priced using both uChips new analogue flash parts and Atmels (flash) a
nalogue
parts, the distributors quoted me half *again* the price for uChip's slower non
vectored
interupt chips !   While people are hooked to uChip there is (I believe) no chan
ce of
serious price drop, uChip  share investors are getting value for money.