arm7 core with fast monolithic 12-bit ADC

On Thu, 12 Feb 2009 14:05:35 -0800 (PST), steve
<bungalow_steve@yahoo.com> wrote:

>On Feb 12, 1:46&#4294967295;pm, Jon Kirwan <j...@infinitefactors.org> wrote:
>
>> Which, obviously, would mean "slower" when talking about monolithic
>> designs with the microcontroller. &#4294967295;It's the combination of speed and
>> ENOB that I'm looking for in a monolithic design and frankly I think
>> it isn't entirely out of the ballpark. &#4294967295;It's a doable, not unreasoned
>> goal I'm looking for.
>
>die designs that are good for CPU's are not good for quiet
>fast accurate A/D's, that's why most A/D's in micro are not even
>speced out
>
>I wouldn't design a product with an internal micro A/D unless I had a
>complete spec or
>I was using it for a simple low res monitor system (<6 bits)

This is a low cost device with loose tolerances, which drove me to at
least look at the possibilities available.

>The ADU series is about the only SAM7 micro A/D that has a decent spec
>(with at least typical SNR/THR/Spurious Noise/Crosstalk
>speced out), it more like a A/D with CPU surrounding it, they put much
>effort into making it meet spec with the core running, whereas most
>other onboard A/D's are an afterthought. SiLabs has speced micro A/D's
>too, but only 8051 based.

That seems to be the wisdom of the day.  I am looking into
experimenting with both, as well as one or two other options.

Jon

On Feb 12, 1:47=A0pm, John Devereux <j...@devereux.me.uk> wrote:
> rickman <gnu...@gmail.com> writes:
>
> [...]
>
> > Yeah, that is what I am thinking. =A0I guess you started out asking for
> > practical advice and this turned into a discussion of theory. =A0The
> > best answer I can give is the ADI ARM7 microverter parts. =A0They have
> > the best ADC/DAC in an ARM MCU that I am aware of. =A0I think someone
> > else already mentioned these parts. =A0They are only so-so in the MCU
> > department, at least in terms of speed. =A0But speed is not always what
> > a design is about.
>
> I get the impression that they took a pretty good ADC (+ good DACs),
> and managed to get a mediocre ARM onto the same die.
>
> Whereas the other manufacturers have higher performance ARMs, with
> better peripherals - except for their mediocre ADCs.

That's a pretty good summary. I've done some work with the ADI
ADuC7026 part and while the analog I/O is good (4 parallel DACs!), the
ARM processor is hamstrung:

* No DMA - all I/O must be programmed through the CPU
* No VIC - Only IRQ/FIQ available and vectoring must be done in
firmware
* Program flash is only 16-bits wide - must use Thumb mode for zero
wait state code access
* SPI interface is limited to ~3MHz clock rate, 8-bits only.

On the upside this part has a parallel external memory bus that comes
in hand for some kinds of interfacing, and it's pretty easy to develop
for. Just don't expect screaming fast performance. I ended up porting
the application intended for the ADuC7026 to a Microchip dsPIC with a
quad SPI DAC and saw about a 2x improvement in throughput.

Eric

On Fri, 13 Feb 2009 07:37:55 -0800 (PST), emeb <ebrombaugh@gmail.com>
wrote:

>On Feb 12, 1:47&#4294967295;pm, John Devereux <j...@devereux.me.uk> wrote:
>> rickman <gnu...@gmail.com> writes:
>>
>> [...]
>>
>> > Yeah, that is what I am thinking. &#4294967295;I guess you started out asking for
>> > practical advice and this turned into a discussion of theory. &#4294967295;The
>> > best answer I can give is the ADI ARM7 microverter parts. &#4294967295;They have
>> > the best ADC/DAC in an ARM MCU that I am aware of. &#4294967295;I think someone
>> > else already mentioned these parts. &#4294967295;They are only so-so in the MCU
>> > department, at least in terms of speed. &#4294967295;But speed is not always what
>> > a design is about.
>>
>> I get the impression that they took a pretty good ADC (+ good DACs),
>> and managed to get a mediocre ARM onto the same die.
>>
>> Whereas the other manufacturers have higher performance ARMs, with
>> better peripherals - except for their mediocre ADCs.
>
>That's a pretty good summary. I've done some work with the ADI
>ADuC7026 part and while the analog I/O is good (4 parallel DACs!), the
>ARM processor is hamstrung:
>
>* No DMA - all I/O must be programmed through the CPU
>* No VIC - Only IRQ/FIQ available and vectoring must be done in
>firmware
>* Program flash is only 16-bits wide - must use Thumb mode for zero
>wait state code access
>* SPI interface is limited to ~3MHz clock rate, 8-bits only.
>
>On the upside this part has a parallel external memory bus that comes
>in hand for some kinds of interfacing, and it's pretty easy to develop
>for. Just don't expect screaming fast performance. I ended up porting
>the application intended for the ADuC7026 to a Microchip dsPIC with a
>quad SPI DAC and saw about a 2x improvement in throughput.

Interesting.  Thanks.

Jon

On Feb 13, 10:37=A0am, emeb <ebromba...@gmail.com> wrote:
> On Feb 12, 1:47=A0pm, John Devereux <j...@devereux.me.uk> wrote:
>
>
>
>
>
> > rickman <gnu...@gmail.com> writes:
>
> > [...]
>
> > > Yeah, that is what I am thinking. =A0I guess you started out asking f=
or
> > > practical advice and this turned into a discussion of theory. =A0The
> > > best answer I can give is the ADI ARM7 microverter parts. =A0They hav=
e
> > > the best ADC/DAC in an ARM MCU that I am aware of. =A0I think someone
> > > else already mentioned these parts. =A0They are only so-so in the MCU
> > > department, at least in terms of speed. =A0But speed is not always wh=
at
> > > a design is about.
>
> > I get the impression that they took a pretty good ADC (+ good DACs),
> > and managed to get a mediocre ARM onto the same die.
>
> > Whereas the other manufacturers have higher performance ARMs, with
> > better peripherals - except for their mediocre ADCs.
>
> That's a pretty good summary. I've done some work with the ADI
> ADuC7026 part and while the analog I/O is good (4 parallel DACs!), the
> ARM processor is hamstrung:
>
> * No DMA - all I/O must be programmed through the CPU
> * No VIC - Only IRQ/FIQ available and vectoring must be done in
> firmware
> * Program flash is only 16-bits wide - must use Thumb mode for zero
> wait state code access
> * SPI interface is limited to ~3MHz clock rate, 8-bits only.
>
> On the upside this part has a parallel external memory bus that comes
> in hand for some kinds of interfacing, and it's pretty easy to develop
> for. Just don't expect screaming fast performance. I ended up porting
> the application intended for the ADuC7026 to a Microchip dsPIC with a
> quad SPI DAC and saw about a 2x improvement in throughput.
>
but does that really matter?

On Feb 13, 9:40=A0am, -jg <Jim.Granvi...@gmail.com> wrote:
> Atmel tend to be at the generic end, and their ADC specs rarely give
> worst case promises on anything - just typicals.
> They are also very new to offering 12 bit ADCs on any uC.

Another (future) data point from Atmel - they have a family brochure
showing the AVR32uC3C as  having Dual 1.5MSPS 12 bit ADCs
and 12 bit DACs and tagged as  'future' in status,

Arrow do show a part code
 AT32UC3C0128-ALUT,
so maybe not too 'future'.?

That is the CAN/USB variant

-jg

On Wed, 25 Feb 2009 14:57:26 -0800 (PST), -jg
<Jim.Granville@gmail.com> wrote:

>On Feb 13, 9:40&#4294967295;am, -jg <Jim.Granvi...@gmail.com> wrote:
>> Atmel tend to be at the generic end, and their ADC specs rarely give
>> worst case promises on anything - just typicals.
>> They are also very new to offering 12 bit ADCs on any uC.
>
>Another (future) data point from Atmel - they have a family brochure
>showing the AVR32uC3C as  having Dual 1.5MSPS 12 bit ADCs
>and 12 bit DACs and tagged as  'future' in status,
>
>Arrow do show a part code
> AT32UC3C0128-ALUT,
>so maybe not too 'future'.?
>
>That is the CAN/USB variant

Thanks.  Although 'future' at Atmel has unique meaning to me (not in a
good way), I do at least enjoy seeing some promises on the subject.
The more the better.  More likely one will get through the vaporware
stage.

Jon

On Feb 26, 3:14=A0pm, Jon Kirwan <j...@infinitefactors.org> wrote:
> Thanks. =A0Although 'future' at Atmel has unique meaning to me (not in a
> good way),

:)

> I do at least enjoy seeing some promises on the subject.
> The more the better. =A0More likely one will get through the vaporware
> stage.

back in October 2008, Ulf said this
"Ulf Samuelsson wrote:
    The AT32UC3C will have a 1,5 MSpl 12 bit ADC, CAN, SPI
    (but not Ethernet), but it wont be sampling until early next year.

and it is now early 2009....  Ulf  ?? :)

-jg

-jg <Jim.Granville@gmail.com> writes:

> On Feb 26, 3:14&nbsp;pm, Jon Kirwan <j...@infinitefactors.org> wrote:
>> Thanks. &nbsp;Although 'future' at Atmel has unique meaning to me (not in a
>> good way),
>
> :)
>
>> I do at least enjoy seeing some promises on the subject.
>> The more the better. &nbsp;More likely one will get through the vaporware
>> stage.
>
> back in October 2008, Ulf said this
> "Ulf Samuelsson wrote:
>     The AT32UC3C will have a 1,5 MSpl 12 bit ADC, CAN, SPI
>     (but not Ethernet), but it wont be sampling until early next year.
>
> and it is now early 2009....  Ulf  ?? :)

What's your problem? - it's still true :)

-- 

John Devereux