AVR-Chat

Sorry if I have missed the point of this thread...  But recently I started
using the Atmel 4mb data flash (http://www.atmel.com/products/DataFlash/),
cheap ($3 in singles) and very easy to use - simpler and cheaper than the
SPI EEprom I was using before.  And those data flash chips get pretty big:
128mbit (16mb).  The main hurdle was ignoring the wacky 264 byte "page" and
treating it as if it were 2 x 256 pages, but every other "page" had only 8
bytes available, so I skipped it.  That was very simple: I just shifted the
linear 32 bit address and inserted a "0" in the 9th bit position before
shifting out to the data flash. The rest was really simple: read a page into
the internal ram buffer, write your data on top, write page back out.  It
was about a screen full of code when I was done.

I have not looked into the SD cards, but since they support a simple SPI
mode and use similar data flash chips, I suspect using them can reduce to a
simple R/M/W operation as well.  
-----------
Larry Barello
www.barello.net


| -----Original Message-----
| From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
| Of Dave Mucha
| Sent: Saturday, November 12, 2005 8:17 AM
| To: AVR-Chat@yahoogroups.com
| Subject: [AVR-Chat] Re: I-Pod
| 
| --- In AVR-Chat@yahoogroups.com, Javier Fiasche <jfiasche@t...> wrote:
| >
| > Dave, why dont you try using Atmel Dataflash memories, i am using a
| > 2Mbytes SPI for a datalogger and works fine. Then, i am sending the
| data
| > via com port to PC. The Pc does not need to have an special programm,
| > just Hyperterminal o anything like that, where you could capture the
| > data on the com port on an archive. Later you could open the data in
| for
| > example Excel , an process it.
| > Try looking on Google for "Built your own microcontrollers projects"
| and
| > the MiniLogger V3.0
| > Regards
| > Javier
| >
| 
| When I started looking at this project, the memory chips were much
| smaller, 256k or such.
| 
| I remember Atmel phasing out the chip i had used and replaced it with
| another chips that was not interchangable.
| 
| One of the problems I had was how the memory was mapped.  IIRC it was
| a whle page write, and the accessable memory was only a fraction of
| the chips.  The address took up half the space....  vague memory of
| the problems.
| 
| That is why I was looking at SD cards.
| 
| The miniLogger project looks interesting
| http://chaokhun.kmitl.ac.th/~kswichit/logger3/logger3.html
| 
| He lists 10,000 reads per 512, but I'm not sure if that is 10k points
| or 10k read of his 4 points....
| 
| To read 40 points per scan and scan once a minute, is 2,400 points per
| hour, his 512k and 10k points would last 4 hours for me, or 8 hours
| per meg.  (If I'm doing the math right)  I'm expecting a week minimum.
| 
| Dave
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| Yahoo! Groups Links
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