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'[EE]:: AVR with USB2 OTG, Ethernet MAC, 128-512 kB'
William Chops Westfield
On May 10, 2007, at 4:48 PM, Russell McMahon wrote:
> An extremely attractive new family of AVR's.
> From their information sheet:
> 32-bit Flash Microcontroller
That's "AVR32" rather than the regular 8-bit AVRs, though.
I dunno if it's just me, but there's a hell of lot of competition
in the 32bit microcontroller space that makes AVR32 less attractive.
Especially since so much of it has architectures that are
multi-vendor (MIPS, PPC, ARM, x86...)
On Thu, 10 May 2007 18:14:26 -0700, Chops wrote:
> On May 10, 2007, at 4:48 PM, Russell McMahon wrote:
>> An extremely attractive new family of AVR's.
>> From their information sheet:
>> 32-bit Flash Microcontroller
> That's "AVR32" rather than the regular 8-bit AVRs, though.
> I dunno if it's just me, but there's a hell of lot of competition in the
> 32bit microcontroller space that makes AVR32 less attractive. Especially
> since so much of it has architectures that are multi-vendor (MIPS, PPC,
> ARM, x86...)
This is pretty funny, I got a chuckle when I read Russel's post initially.
I went to the last Atmel seminar in our area. Some factory guys from Norway
were there and giving the presentations on the new chips. They covered the
8-bit AVR stuff, the 8051 core stuff, the ARM7 and ARM9 core stuff and then
During the Q&A I asked them "Isn't the AVR32 pretty much the same
peripheral mix, memory space and CPU horsepower as the ARM7/ARM9 core
chips? It seems to me they are in direct competition with each other."
The answer I got was amusing... something like "Oh no, the CPU is our own
design coming from our team in Norway. While they are similar in
capability, peripheral and memory mix, we don't see it being in direct
competition with the ARM core parts at all"
Uhhh, yeah... right. It was also amusing talking to my friend who's the
Atmel rep. here. I asked him if he's seen any interest in the AVR32 over
the the ARM core parts. He just gave me a funny look and rolled his eyes.
I'll be really surprised if the AVR32 family is anything but a small niche
player in the 32-bit market.
Maximum Performance Systems
On Fri, 11 May 2007 14:58:20 +1200, Russell McMahon wrote:
>> This is pretty funny, I got a chuckle when I read Russel's post
> Nice to know I am amusing :-).
>> During the Q&A I asked them "Isn't the AVR32 pretty much the same
>> peripheral mix, memory space and CPU horsepower as the ARM7/ARM9 core
> What made me give i 'the time of day' ws the USB2 OTG interface. All the
> rest was pretty good too, but having hardware 12 Mbps OTG buolt in is
> Are there any ARMs with OTG capability>
I haven't looked in about a year or so, that's when I last did any work
with ARM and USB. At the time there were quite a few "higher" ARM chips
with OTG, for example the Intel PXA270 family (which we were using). We
ultimately dropped USB OTG from the product, initially our thinking was one
USB port to do both host and client interface. We ended up with both a host
and client port instead. The main reason was lack of driver support and the
complexity of the OTG interface (hardware AND software).
It turns out it's actually easier and better supported on the software side
to do a full host interface than an OTG interface. There is a pretty
convoluted negotiation that has to take place for the "host" to decide it's
a host and set everything up correctly. It also depends on the connected
device to respond properly and that doesn't always happen either.
There's also a lot more host stacks available for OSs like WinCE and Linux.
OTG is not very well supported on the device side either. All the client
device manufacturers assume you'll be running a PC (Windows, Linux, etc.),
or an embedded device running WinCE or Linux and have a real host port so
that's all they write drivers for. Running without a "real OS" and you are
in the land of writing your own low level drivers and the device
manufacturers don't want to even talk to you or if you come bearing loads
of $$$ they might talk to you.
I'm not aware of any ARM7 or ARM9 class CPUs that have OTG but there are
definitely some with host ports or both host and client ports.
I'm no USB expert but the software guys (who were very good and had some
significant USB experience) concluded that OTG was a good idea on paper but
that it was a fairly daunting task to implement. Their conclusion was that
it was just easier all around to use a chip with a real host port and
implement that. I know the hardware interface is more complicated for OTG
as it has to be switchable between host and client and all that entails.
Back in the day when the only chips that had host ports were PC South
Bridge chips or PCI USB controllers, OTG probably looked like a good idea
for embedded systems. But with the host controllers built into a lot of MCU
chips these days it doesn't make as much sense (to me). Maybe things have
gotten better on the OTG front but I still haven't seen many devices that
work with it.
Maximum Performance Systems
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