which microcontroller for data acquisition and storage?

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Hi all,

I am having trouble finding the right microcontroller chip.
I need a chip that has large amounts of RAM on-board,
because I need to store many millions of 16-bit data,
which will later be uploaded to a PC. I would prefer something
that is a good match for my limited prototyping setup,
i.e. which has a DIP package.

But does such a thing exist?

Thanks for any help.

Re: which microcontroller for data acquisition and storage?
I don't there's any microcontroller with several megabytes of RAM on it. If you
need that kind of RAM, you're best off using a microprocessor or a
microcontroller that can access external memory chips.

Re: which microcontroller for data acquisition and storage?

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I don't know of anything with that much memory directly.  Even my MAVRIC
board which has 128K of RAM and is considered a lot for a typical micro
does not have enough for that.  But you may look into interfacing with a
compact flash card which come in a variety of sizes.

For example, see the following for instructions on how to hook up and use
a compact flash card to an AVR.  Code is BASCOM-AVR:

    http://www.mcselec.com/an_127.htm

Cheers,
-Brian
--
Brian Dean, snipped-for-privacy@bdmicro.com
BDMICRO - Maker of the MAVRIC ATmega128 Dev Board
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Re: which microcontroller for data acquisition and storage?
Microcontrollers don't have millions of words of RAM, most have 4096 bytes
or less.
Some microcontrollers can handle up to 128k to 256k bytes of RAM externally
though.
What it looks like you really want is a DSP like those from Texas
Instruments. The higher end ones can handle upwards of
32bit and 64 bit external memory addressing. So you could pile in a lot of
external memory on these suckers.
32bit gives you gigabytes of data storage.
http://dspvillage.ti.com/docs/dspvillagehome.jhtml

If your on a budget, your going to have to settle for a Intel CPU based main
logic board like those used in a PC,or  maybe a PC-104 style board, or a SBC
solution,
then you could max out the RAM on the board and even use a hard disk to
store data. You could run most any OS you want too.
The ARM based CPU's may be promising but most of these have PCB's with 1meg
of RAM and of flash being normal. Some have maybe up to 4meg.





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Re: which microcontroller for data acquisition and storage?
On Sat, 13 Sep 2003 21:43:53 -0500

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Theres a lot more choice than that! try the LART and offerings from Simtec

--
Spyros lair: http://www.mnementh.co.uk/ ||||   Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with ketchup.

Re: which microcontroller for data acquisition and storage?
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No.


 You should define just what 'many millions' actually means,
and also the storage rate, and upload rate needed.

 If the readings are slowly changing ( well correlated ) then
compression is a candidate.

 The most common solution for this problem, is off-chip
serial storage. Atmel Data FLASH has interleaved RAM buffers,
so can support a reasonable storage rate.

 For a possible single chip, the uPSD from STm has half
a megabyte of FLASH, 32K SRAM, and USB ( for fast upload )

-jg

Re: which microcontroller for data acquisition and storage?
Thanks for all the replies, folks.

About the CompactFlash option, that's a good idea. Although
I will need to read as many data as I can per second,
and I am wondering what the limit is for writing to flash.
The last time I looked at flash, many years ago, the write
speed was low. But then these days I know it is faster.

Also, there is a Circuit Cellar project that does just
that. The guy connected a PIC processor to a CompactFlash
socket, using the 8-bit access mode of the CompactFlash
standard rather than the IDE approach. So it is slow,
but the idea is clever.

About microcontrollers with lots of RAM, I discovered
one that is intriguing: the MRM (Mini Robot Mind).
It's here: http://www.robominds.com/minirobomind.htm
It can take up to 1 meg using a daughter card and
the guy who produces it is about to release a daughter
card that takes CompactFlash. The main board is only
$99 and has a 68332(?). The only comparable thing I know
of is a discounted 386SX board that I found, which is not quite
as good for me although I suppose it would run Linux.

Thanks again...

Re: which microcontroller for data acquisition and storage?
If 1Mb is enough then look at serial data Flash from Atmel, as suggested
elsewhere. This goes up to 8Mbytes. Else an MMC card can go up to 1Gb
these days. as to micros, well that depends on your data logging needs.
If your needs are simple I have a built board with a 2Mb serial data
flash and either an MSP430F1121 or an MSP430F149 on it, in both cases
there is also an RF transceiver, but I have the bare boards if you want
to get the parts and load your own. The tools for this micro are cheap,
free software and $10 program/debug interface.

Al

flarkblark wrote:
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Re: which microcontroller for data acquisition and storage?
Why not using directly a PC-compatible module with a PCMCIA socket, like a
PC104 form-factor ones ? You can then easily find 64 or even 256Mb memory
modules, and the software support is built-in.

Cheers,
Robert Lacoste - ALCIOM : The mixed signals experts
http://www.alciom.com


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Re: which microcontroller for data acquisition and storage?
I was under the impression that PC104 is expensive. If not so,
I would be happy to give that a try. I don't want to spend more
than $150 on the board, so if PC104 is above that threshold
I think the Mini Robot Mind will be my likely choice. Cheers-

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Re: which microcontroller for data acquisition and storage?
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I've used an Atmel Mega8L CPU and AT45DCBxxx DataFlash with SPI serial
connection to create a data logger. Works quite well. The flashcard has
on-board RAM buffers allowing you to collect your samples and when the
buffer is full, write to Flash.

Rob



Re: which microcontroller for data acquisition and storage?
As others have mentioned, on-chip memory
is usually very limited, but many can handle
good amount of external memory, with SRAM
usually being the easiest to work with.  Also,
often you can have more memory than speced
-- once I had an 8051 with 128kb memory.

But if you want to do data acquisitiion and upload
the data to a PC, why don't you just get a DAQ
card and install it in a PC ?!   With a PC you can
have gigabytes of memory and the upload part
will get factored out.

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Re: which microcontroller for data acquisition and storage?
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Well I wanted to do the acquisition on-site, and the PC is
far away. However I may be able to get a laptop as a temporary
solution, in which case I think there is a $50 parallel-port
DAQ solution that will work.

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