Temporizzazioni MMC

Ciao a tutti!
Qualcuno ha un'idea delle temporizzazioni necessarie per le memorie MMC?
Mi spiego meglio, qualcuno conosce il transfer rate per una scrittura 
continua su questi dispositivi? (riferendosi a una MMC "media" odierna, 
da 512MBytes).

Vorrei realizzare un datalogger, che abbia una banda di 150KBytes/sec in 
scrittura sulla MMC, e mi chiedevo se con queste memorie la cosa fosse 
fattibile o meno.

Ho visto che esistono scritture
-single block
-multiple block
-burst

Il dato che proprio non riesco a trovare da nessuna parte e' la durata 
di un trasferimento "single block" (512 bytes).


Grazie a tutti e ciao!
Aldo

Bongiorno Aldo,

> Vorrei realizzare un datalogger, che abbia una banda di 150KBytes/sec in 
> scrittura sulla MMC, e mi chiedevo se con queste memorie la cosa fosse 
> fattibile o meno.

I don't understand Italian much but I think it would be best to ask the 
supplier, for example Lexar, for a detailed data sheet. This speed does 
not sound very high, should be possible.

Have you also considered SD cards? Supposedly they are really easy to 
communicate with and they are physically very small. Also, at least in 
the US you can almost buy them at every street corner.

Ciao, Joerg

http://www.analogconsultants.com

I'm so sorry..... my intention was to post this on an italian newsgroup, 
but I unintentionally posted it here...I apologize....seems that I 
pushed the wrong button on my mailer.

Anyway, thanks for your answer,you exactly got the point :-)

I think it should be possible, too, because digital cameras seem to 
write data at a higher speed.

Concerning SD, is the specification publicly available like MMC or CF, 
or has to be purchased?

Bye!
Aldo



Joerg wrote:
> Bongiorno Aldo,
> 
>> Vorrei realizzare un datalogger, che abbia una banda di 150KBytes/sec 
>> in scrittura sulla MMC, e mi chiedevo se con queste memorie la cosa 
>> fosse fattibile o meno.
> 
> 
> I don't understand Italian much but I think it would be best to ask the 
> supplier, for example Lexar, for a detailed data sheet. This speed does 
> not sound very high, should be possible.
> 
> Have you also considered SD cards? Supposedly they are really easy to 
> communicate with and they are physically very small. Also, at least in 
> the US you can almost buy them at every street corner.
> 
> Ciao, Joerg
> 
> http://www.analogconsultants.com

Hello Aldo,

> I'm so sorry..... my intention was to post this on an italian newsgroup, 
> but I unintentionally posted it here...I apologize....seems that I 
> pushed the wrong button on my mailer.

That's ok, I guess we are all pretty international in these newsgroups 
anyway. I bought a TV in Germany a long time ago. The manual was in 
Dutch/Danish/Swedish and the buttons on the front were marked in 
Italian. Oh well. Still works fine. When I read "Unita d'alimentazione" 
in an Italian schematic I somehow craved a nice Italian dinner...

> I think it should be possible, too, because digital cameras seem to 
> write data at a higher speed.

Yes, mine writes a 1MB JPEG set in about a second or so but it uses an 
older Lexar flash card. Reading it down to the PC is even faster. A 
friend has one with an SC card and it also stores a whole picture of 
probably 2MB worth of compressed data in less than a second. You can 
even record realtime movies with it.

> Concerning SD, is the specification publicly available like MMC or CF, 
> or has to be purchased?

The manufacturers have that, along with application notes about more 
unusual writing schemes such as 1-bit wide writing. I would look at the 
mfg web site. You may have to contact them. Also, this topic is often 
discussed in great detail in micro controller newsgroups such as the 
Yahoo MSP430 group. There you can also get help if things don't want to 
work as expected.

For MMC and SD here is an overview to start with:

http://www.sandisk.com/pdf/oem/AppNoteMMC_SDv1.0.pdf

Then, on to more detail when your design begins:

http://www.sandisk.com/oem/manuals.asp

Another good source is this organization:

http://www.sdcard.org/

Ciao, Joerg

http://www.analogconsultants.com