Microchip has been around 20 years ago. Most of its products are
back-compatible (the 16F84 for example, is compatible with the popular 16C5X
line). AVR90S2313 on the other hand entered full production just last month.
So many of us learned to work with PICs when there was nothing else close in
terms of price, performance, I/O capability and small pin count. Is not to
say that some of us are "hooked" with PICs, but when presented with a
project, is second nature to imagine a PIC design. Thinking about an AVR
desing means a new assembler, a new programmer, new tools, etc, that will
add up to the project delivery time.

On the other hand, if you are "new" to microcontrollers, there is now a much
wider selection than just a few years ago.

Regards,
Andres Tarzia
Technology Consultant, SMART S.A.
e-mail: atarzia@smart.com.ar

-----Original Message-----
From: Russell McMahon [mailto:apptech@CLEAR.NET.NZ]
Sent: Wednesday, March 10, 1999 07:55
To: PICLIST@MITVMA.MIT.EDU
Subject: WHY USE PICs???


Intentionally provocative (but serious) question :-)
This isn't just meant to be a shootout - its a real question.
Given the following comparison, why should I keep using 16F84's or
any 14 bit core PIC?
12 bit core MAY still have a place where price is paramount.

Make Microchip's day - tell me (and everybody else)why.

As well as using other processors, I have been using PICs for some
while.
Initially because a Customer felt he had to use PICs for good but
irrelevant reasons and subsequently due to the 16F84's Flash
programmability, eerom, robust and good drive i/o and a few other
reasonably good reasons.

I am investigating the AVR - especially the AT90S2313. I have of
course been aware of AVRs for some while but have not spent any time
on them.

In the following I'll say "AVR" when I mean AVR90S2313 unless
otherwise noted.

The AVR has

UART,  full duplex
ISP,
1K word (16 bit)Flash, (1K cycles)
128 byte eeprom (100K cycles)
128 bytes true RAM
Comparator,
2 external interrupts,
PWM (8,9 or 10 bit)
2 timers
    8 bit with own prescaler.
    16 bit with own prescaler and compare & capture     , 16 bit has
autoreload)
Watchdog
15 i/o in 20 pin skinny DIP (or various smd's)
External/internal clock
1 MIP almost per MHz
Vcc = 4 - 6v at 0 - 10MHz (10 MIPS ish)
Vcc = 2.7 - 6v at 0 -4 MHz

**** Linear non-paged address spaces which scale up to larger members
of family ****
(hooray, hooray!!!!)

etc

**** COSTS $NZ4.80 =~ $US2.75 in SMALL quantities ****

AVR has real instruction set (much like a 6809!!! :-))
Real ROM read for tables(none of this RETLW stuff).
You get the idea.

AVR i/o drive inferior to PICs
No doubt other "gotcha's" that I have yet to find out about.
Also needs external anti-brownout cct for safety (unbelievable in
this day and age).

Demo board / programmer / floppy & CD software etc for $NZ105 =~
$US55
Demo board has 8 lights / switches, RS232 buffer with drivers,
parallel port connection to pc, misc other useful features, more
sockets for programming variants than you would believe they could
fit on the board etc.

Can have software free and build own programmer for about $0 (as per
PIC)

To me this seems to be an extremely impressive feature list compared
to eg 16F84 or any other comparable PIC. Versions with more pins and
more Flash and a few more features are available for more $.

I have been unhappy with 16F84 prices of late - this AVR leaves them
for dead.
Price seldom matters vitally in hobbyist volumes but for small run
production it can and for real volume ...



regards

            Russell McMahon