Atmel frustration

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We are going to move from some Motorola controllers to ARM ones.  We have
been looking at several chips from different manufacturers.  The Atmel
AT91RM9200 looksk interesting - but after reading the datasheet for a while,
I started wondering whether they are completely sane at Atmel.

For example, the I/O pin organization is a big mess.  We want to use all
UARTs with control lines, all timer channels, Ethernet, digital audio -
ah!  This is not possible!  If we use Ethernet, we lose some UART control
lines.  If we use the timers, we lose more.  If we want audio, we lose the
rest of the timer pins.  Etc. etc. etc.  Take a look at Motorola MMC2114,
for example: no mess, all (99%) pins have only two functions: GPIO or a
special function.

I'm glad we're not going to use the synchronous serial ports.  They have
no HDLC supprt (what kind of sync ports are they, anyway?).

On software side, the Ethernet controller looks pretty dumb to someone
who's seen Motorola stuff from mid-90's.  Frames must be stored in
contiguous memory (so, if we want to transmit an mbuf chain (a packet
split into multiple 128 or 256 byte buffers), we must first copy the
packet from the mbuf chain into a separate buffer using CPU, and then
start Ethernet transmission (and only one frame is automatically sent
by the hardware).  See some old (or new) Motorola chips (like 68en302)
and learn how things should be done.

Multiple interrupts are routed to same interrupt vector, so the interrupt
handler must poll the peripherals to see what's up.  On MMC2114, you can
use a different vector for virtually every interrupt source (OTOH, you
can also route all interrupts to one vector if you like).

Sigh.  Did they do anything right?

We also looked into the ARM7TDMI chips from Atmel, the ones with large
SRAM and FLASH sounded ice for smaller applications.  They did - until
we found out that the FLASH is dead slow.  A 70 MHz CPU with no caches -
and they use 90 ns 16-bit wide FLASH!?  I bet a 33 MHz MMC2114 with 32-bit
zero-wait-state FLASH runs in circles around this fine 70 MHz Atmel.
Even Philips knew better when designing their LPC210x series of chips.

Sorry, I'm just pretty disappointed in Atmel chips.  They have lots of
features, sure, but if you can't use all features thanks to the I/O
pin mess and if the hw is this limited...

Don't shoot me, I'm trying to adjust to these shortcomings.. It will
be difficult, I had a nightmare about the I/O pin conflicts last night..


Re: Atmel frustration
So why move?

Re: Atmel frustration
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Because Motorola has all but said "get away from MCORE or we'll screw you."

MCORE is like the stereotype cool friend in gangster movies that now has a
contract on his head and so no one wants to be near the poor guy anymore.
So now a *bunch* of people are moving away from perfectly good chips and
heading toward slapdash ARM solutions like the AT91RM9200.

Re: Atmel frustration
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What a shame. I wonder why they made that decision? Sometimes I think it's an
amazing thing that companies actually make money.

Re: Atmel frustration
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I'm not sure that Motorola is making money.  In fact, they're making very
little, period.  They've outsourced almost everything, including their
phones.  Designed, managed, and built by 3rd parties.

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My best guess is that they got the impression that everyone wanted
ARM instead, so they bought a license for ARM ...

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Re: Atmel frustration
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Made sense to me.
 They instead emphasise their PowerPC - which have some very powerfull
variants, and the Dragonball family ( which is now actually two cores,
the ARM being the newest ).
 That gives them three 32 bit arena solutions (and all with a wealth of
SW maturity),
as well as their DSP families on the side.

 The Atmel ARM offerings are microprocessors (not single chip) rather
microcontrollers, so it's a bit of an apples and oranges thing to


Re: Atmel frustration

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I take you don't really need the performace of an ARM9 core if you looked at
the smaller Atmel chips. Than you might find the EP7312 from Cirrus Logic or
the LH79520 from Sharp interesting. No integrated Ethernet though... Cirrus
has chips with integrated Ethernet but they come in BGA packages.

Also, I would take a look at the errata before choosing a chip. Today it
seems they pack a bunch of functions in these SoC solutions without much
debugging. The result is an errata of 10 pages long :-(.

Andras Tantos

Re: Atmel frustration
Why did you want to move away from Motorola? Because they are more
expensive? Well, less expensive, less pins. To some degree you get
what you pay for. The difference, in the ARM world, there are a lot of
competing companies, Atmel, Sharp, Netsilicon, Philips, Samsung...
and many more
So, stay mit Mot if you doubt that lower prices do not make up for a
little more thinking on the developers site ;-)


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Re: Atmel frustration
Interesting...I just checked the Sharp web-site and noticed they have two
new offerings (LH79524 and LH79525) that include a 10/100 Ethernet MAC.
These are ARM720T based devices so you get the cache.  With the SDRAM
interface included, these should be some nice devices!  If this is based of
the LH79520, you should get a pretty clean part.  There are only 3 errata
listed for the LH79520.


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Re: Atmel frustration
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Well, LH79525 goes into production in 2004 and prices is still unknown..
It has no CF support (one reason we chose AT91RM9200).. but sure, for
some other purposes, these might be nice chips.


Re: Atmel frustration

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Actually, if you use the BGA package, I think some of this multiplexing is
relaxed a bit.

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Thanks for all the follow-ups.  We have been studying the AT91RM9200 for a
few days now, and we _think_ we can do almost what we wanted with it.
It still does look like a mess and less intelligent to a long-time Motorola
user, but we have our own embedded OS and after writing the drivers for
the Atmel, I hope we can pretty much forget about the insanity of the
hardware (well, until the next project is started, that is).

I want to get away from Motorola because their MCU's have become buggy and
cost me a lot of money (take 68HC912D60A, for example: it has oscillator
problems and erases all the FLASH at random times).  They also screwed us
by first announcing a roadmap for the MCore family, and then stopping the
development after MMC2114.  It's a nice, clean, and fast chip, but with no
new versions (read: more memory, Ethernet controller etc.) coming, it feels
kind of dead already.  We looked at the PowerPC based chips and while they
are nice, we don't really need all the horsepower at the moment.

Why ARM, then?  Well, it looks like a good solution because everybody makes
ARM based chips these days, so you do not depend on only one manufacturer
(although I realize that some redesign would be required when moving from
manuf A to manuf B as the chips are not identical).  ARM is supposed to
have a good MIPS/mW ratio, some chips have lots of peripherals, they are
relatively cheap etc.

We have several projects in the FIFO, so we are looking for different kind
of chips.  I think I'll even use the Philips LPC2100 series for some single
chip stuff (where we used MCore before - in most projects, though, we used
MCore in the expanded mode, because we needed an LCD controller, more SRAM
and FLASH, an Ethernet controller etc - so MCore wasn't just a single chip
system to us).  (I also have a love/hate relationship with PIC's, but
that's a different story ;-)

About hardware bugs: Atmel's errata is long enough.. I hope we won't run
into unknown problems like we have with Motorola.. I guess that's what you
get for using new chips.


Re: Atmel frustration
Hi Jukka -
What you have written is equal to my mine. Motorola lost their great spirit
after structuring their business new. I loved the 68000 (32-bits linear,
etc.). That was in time of the 8086. Just compare the twos!!
If you have so much projects, is it possible to get some work? I'm
- Henry

Jukka Marin schrieb in Nachricht ...
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Re: Atmel frustration

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You are too demanding !

Go working with a Samsung S3C3410.
Try to study the Datasheet.
Use the nWAIT pin.
Use the prioritized Interrupt controller.
Use asynchronous external interrupts.

Raymund Hofmann

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