Use USB memory stick as random memory?

[Bill Bowden]

Is it possible to use a little USB flash drive as RAM memory for a PIC
microcontroller project without a lot of serial I/O software?

How complicated is it?

What procedure is needed to read and write a single byte to some
location inside the USB flash drive?

I'm guessing it requires writing and reading entire files to move
small bits of data.

-Bill

 

[Nicholas Sherlock]

Bill Bowden wrote:

Is it possible to use a little USB flash drive as RAM memory for a PIC
microcontroller project without a lot of serial I/O software?

How complicated is it?

What procedure is needed to read and write a single byte to some
location inside the USB flash drive?

I'm guessing it requires writing and reading entire files to move
small bits of data.

The drive doesn't know anything about files. You read and write blocks
of data to locations on the flash. You have to implement USB host and
issue USB commands over the wire, which is pretty painful. Why do you
want to use a USB flash drive? You might be better off with, say, an SD
card, which has a far simpler interface designed for small devices to
implement.

Cheers,
Nicholas Sherlock
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[Rich Webb]

On Sun, 15 Jun 2008 18:07:28 -0700 (PDT), Bill Bowden
<wrongaddress@att.net> wrote:

Is it possible to use a little USB flash drive as RAM memory for a PIC
microcontroller project without a lot of serial I/O software?

Nope.

How complicated is it?

Fairly. You'd need to implement a "USB host" to talk to the USB flash
drive. Depending on which side of the build/buy equation you're on, you
can get pre-packaged interface libraries.

What procedure is needed to read and write a single byte to some
location inside the USB flash drive?

I'm guessing it requires writing and reading entire files to move
small bits of data.

If you have to have a USB drive (customer requirement, etc.) then you
do. But, if you just want a ton of flash storage, then it's probably
easier to implement an SPI driver for SD cards in MMC mode.

Here's a link to a PIC project that does just that
http://www.captain.at/electronics/pic-mmc/

--
Rich Webb Norfolk, VA

 

[Tim Wescott]

Bill Bowden wrote:

Is it possible to use a little USB flash drive as RAM memory for a PIC
microcontroller project without a lot of serial I/O software?

How complicated is it?

What procedure is needed to read and write a single byte to some
location inside the USB flash drive?

I'm guessing it requires writing and reading entire files to move
small bits of data.

-Bill

Whatever you do, it'll be dog slow compared to real RAM.

Do you want this for non volatile storage? I'd go with the suggestions
to use an SD card, or if your storage requirements are modest an 8-pin
serial EEPROM.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[Bob Monsen]

"Bill Bowden" <wrongaddress@att.net> wrote in message
news:fade7581-4f17-4fd4-8c68-bef6cfb40eba@y38g2000hsy.googlegroups.com...

Is it possible to use a little USB flash drive as RAM memory for a PIC
microcontroller project without a lot of serial I/O software?

How complicated is it?

What procedure is needed to read and write a single byte to some
location inside the USB flash drive?

I'm guessing it requires writing and reading entire files to move
small bits of data.

-Bill

If you want to use SD, you might use this:

http://www.futurlec.com/Mini_SC.shtml

It is a 'miniboard' from those Australian guys. You can use it to read and
write an SD card. It is basically just a breakout board, but you won't have
to run your own board.

Regards,
Bob Monsen

 

[Don McKenzie]

Bill Bowden wrote:

Is it possible to use a little USB flash drive as RAM memory for a PIC
microcontroller project without a lot of serial I/O software?

How complicated is it?

What procedure is needed to read and write a single byte to some
location inside the USB flash drive?

I'm guessing it requires writing and reading entire files to move
small bits of data.

1)
http://www.dontronics-shop.com/4d-udrive-usd-g1-tiny-disk-drive-data-storage-module.html

2)
http://www.dontronics-shop.com/ftdi-vdrive2.html

Cheers Don...



--
Don McKenzie

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E-Mail Contact Page: http://www.dontronics.com/email

Xbee Wireless Modules, and low cost Interface Boards.
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