Servo Movement Recording (Data Logging?)

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volt dropper
 
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Post by volt dropper »

If all you want to know is how to write to an SD card from an Arduino, goodness, google is your friend. Look at the very first hit:

http://jvcideas.blogspot.com/2007/08/ad ... tep-1.html

There are dozens of relevant hits if you dig a bit.

But I think you'll find that's only one piece of a very large puzzle.

pd2kplus10
 
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Post by pd2kplus10 »

I looked at the a while ago ... doesn't provide much info. He hasn't been able to figure out how to use it.



Phil

mtbf0
 
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Post by mtbf0 »

so, do you want a file system or to just dump some data on the card?

have you considered a serial eeprom?

pd2kplus10
 
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Post by pd2kplus10 »

No need for a file system ... just dump it in memory.

I found a 2MB serial eeprom somewhere ... it was cheap like $4 or something. I think it may work. The only thing I would worry about with that is the # of times you can write to it .... it's somewhere around 10,000 writes before it's no good.



thanks,
Phil

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darus67
 
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Post by darus67 »

The flash memory in SD cards has the same problem.

Even so, if you were to erase and re-write the thing 10 times a day,
every day, it's still good for nearly three years. By then it's obsolete.

pd2kplus10
 
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Post by pd2kplus10 »

I thought the memory used in SD was good for much longer.



Phil

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darus67
 
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Post by darus67 »

I'm not sure how many cycles it's good for, but it still has a finite lifetime.

mtbf0
 
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Post by mtbf0 »

one thing about sd cards is that they require 3.3v. so you need dual power supplies, (i guess you'll neeed this anyway if you're going to use an mp3 decoder), and voltage dividers on all the inputs to the sd.

eeproms can be had as 5v parts and here's a tutorial i found that describes hooking up a 64k atmel part to the arduino.

http://www.arduino.cc/en/Tutorial/SPIEEPROM

adafruit
 
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Post by adafruit »

pd2kplus10 wrote:I thought the memory used in SD was good for much longer.
sd cards are quite sneaky, inside theres a microcontroller that keeps track of what blocks of memory are used and re/distributes them 'evenly' so that they all have even wear ("wear leveling")

pd2kplus10
 
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Post by pd2kplus10 »

That 64KB EEPROM link is nice. I think I will start with that for now and see if I can make this work.

Has anyone seen this: http://www.futurlec.com/Mini_FLASH.shtml

... looks pretty cool. 2MB memory and cheap.



thanks,
Phil

mtbf0
 
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Post by mtbf0 »

interestingly, that flash part is also available in an mmc/sd form factor and i think i've got a device that uses it, so if you tire of the serial eeprom and switch to the dataflash let us know.

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