need help in choosing a microcontroller

Can you please advise a microcontroller? It looks like nobody cares to
list
devices from competing manufacturers in the same document, providing
both prices and features.

There is a project, I need to process data of frequencies 0.5-40 Hz.
FFT and such. For FFT, the array will be 2^N.
FFT will be used to eliminate the "high"-frequency noice (50+ Hz).
(If you think that something would be an overkill, I will gratefully
listen to your opinion.)

requirements on the MCU:
 - low power consumption
 - 12-bit ADC
 - room for FFT data, 32K or more of RAM. (Combinations like 32K + 2K
also may be useful)
 - cheap: $1 optimal, $10 max. (or _a_bit_ more)
 - there are 2 modification of the problem, one needs plotting the
form of the signal on the LCD display, another does not need any LCD;
therefore, if some MCU that comes in two versions, one with LCD
support, and another without, that would be great.
 - programming languages: at least C; Forth or C++ would be even
better. Free compilers are preferable (that is, it's "free" when its
cost is included into the chip cost)
 - word size: I will consider all options, 8/16/32/24.

m_l_g3 wrote:

> Can you please advise a microcontroller? It looks like nobody cares to
> list devices from competing manufacturers

[...]

A young guy and young girl came to the rabbi to ask for his advice.

A girl:

"Tomorrow is my first night with my fiance. What kind of night dress 
should I put on? Should it be a long dress, or a short dress, or an open 
dress, or a closed dress, or whatever?"

A boy:

"I got some money. Will you please give me an advice what to do with it: 
maybe, invest into something, or buy some real estate, or gold, or put 
it in a bank?"

The rabbi:

"My dear children, I have one answer for both of you: whatever you do, 
you will certainly be fucked."


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

On Feb 7, 10:52=EF=BF=BDpm, m_l_g3 <m_l...@yahoo.com> wrote:
> Can you please advise a microcontroller? It looks like nobody cares to
> list
> devices from competing manufacturers in the same document, providing
> both prices and features.
>
> There is a project, I need to process data of frequencies 0.5-40 Hz.
> FFT and such. For FFT, the array will be 2^N.
> FFT will be used to eliminate the "high"-frequency noice (50+ Hz).
> (If you think that something would be an overkill, I will gratefully
> listen to your opinion.)
>
> requirements on the MCU:
> =EF=BF=BD- low power consumption
> =EF=BF=BD- 12-bit ADC
> =EF=BF=BD- room for FFT data, 32K or more of RAM. (Combinations like 32K =
+ 2K
> also may be useful)
> =EF=BF=BD- cheap: $1 optimal, $10 max. (or _a_bit_ more)
> =EF=BF=BD- there are 2 modification of the problem, one needs plotting th=
e
> form of the signal on the LCD display, another does not need any LCD;
> therefore, if some MCU that comes in two versions, one with LCD
> support, and another without, that would be great.
> =EF=BF=BD- programming languages: at least C; Forth or C++ would be even
> better. Free compilers are preferable (that is, it's "free" when its
> cost is included into the chip cost)
> =EF=BF=BD- word size: I will consider all options, 8/16/32/24.

A crazy question fully deserving of the answer it got. get your
project organised then ask a question that makes sence if you still
need to.

On Feb 7, 5:52 pm, m_l_g3 <m_l...@yahoo.com> wrote:
> Can you please advise a microcontroller? It looks like nobody cares to
> list
> devices from competing manufacturers in the same document, providing
> both prices and features.
>
> There is a project, I need to process data of frequencies 0.5-40 Hz.
> FFT and such. For FFT, the array will be 2^N.
> FFT will be used to eliminate the "high"-frequency noice (50+ Hz).
> (If you think that something would be an overkill, I will gratefully
> listen to your opinion.)
>
> requirements on the MCU:
>  - low power consumption
>  - 12-bit ADC
>  - room for FFT data, 32K or more of RAM. (Combinations like 32K + 2K
> also may be useful)
>  - cheap: $1 optimal, $10 max. (or _a_bit_ more)
>  - there are 2 modification of the problem, one needs plotting the
> form of the signal on the LCD display, another does not need any LCD;
> therefore, if some MCU that comes in two versions, one with LCD
> support, and another without, that would be great.
>  - programming languages: at least C; Forth or C++ would be even
> better. Free compilers are preferable (that is, it's "free" when its
> cost is included into the chip cost)
>  - word size: I will consider all options, 8/16/32/24.


I don't want to be as rude as the other posts you received, but the
questions you ask show that you have little experience with embedded
CPUs or DSP.  First, I seriously doubt that an FFT is the best way to
implement a low pass filter.  You have not said anything about the
sample rate you are interested in using.  This has an impact on the
filter implementation.  If you use a delta-sigma ADC with a single
pole anti-alias filter, you can likely get away with no filtering in
software.  But then a 40 Hz low pass filter is pretty slow to try to
do directly with the ADC filters.  More likely you will end up with an
FIR filter and a sample rate around 4 or 8 kHz.  This will let you use
a 1 pole anti-alias filter.

Regardless, it is unlikely that you need 32 KB of RAM for this.  That
brings us to the second way that you seem to be unprepared for this
task.  Rather than to try to select an MCU part based on the sparse
information you have, you would do better to explore your algorithm/
software design on a PC first.  This will let you make informed
decisions about the tradeoffs of sample rate, ADC choice and software
design.  Then you can choose a part to implement the design.

On the other hand, there are a large number of devices out that that
will meet the requirements you have laid out.  The LCD support will
limit your choices more than anything.  But if you don't understand
the things I have written above, it is not likely a good idea for you
to proceed without help.

Rick

On Feb 7, 4:31=A0pm, Vladimir Vassilevsky <antispam_bo...@hotmail.com>
wrote:
> A young guy and young girl came to the rabbi to ask for his advice.
> [...]
I love this newsgroup.
-Brad

On Feb 8, 11:52=A0am, m_l_g3 <m_l...@yahoo.com> wrote:
> Can you please advise a microcontroller? It looks like nobody cares to
> list
> devices from competing manufacturers in the same document, providing
> both prices and features.

You should specify the volumes expected too.

It might be smarter to settle on ONE MCU, and have the LCD as
a separate slave module - how much display bandwidth do you need ?

-jg

On Feb 8, 5:54=A0am, -jg <Jim.Granvi...@gmail.com> wrote:
> On Feb 8, 11:52=A0am, m_l_g3 <m_l...@yahoo.com> wrote:
>
> > Can you please advise a microcontroller? It looks like nobody cares to
> > list
> > devices from competing manufacturers in the same document, providing
> > both prices and features.

Yes, IAR's Arm community website do this here:
http://www.sevensandnines.com

Go to chip selector and advanced search, i find it limited, could be
better, but not too bad