AVR SD Card Reader

[Nathaniel Lewis]

I got an avr sd card reader/writer program working on the ATmega644!  It even supports FAT though the ELM FatFs module (URL is in the main program).  It should compile just fine under WinAVR and just redo the makefile and include a #define F_CPU 10000000UL in the main code for Mac and Linux.  Here is the link for it is kind of large. http://the-linbot-project.googlegroups.com/web/FatFsSDC.zip?gda=V3Eriz4AAAALx3cvYwaQyG90c_0UB0YzmCVJ5HuQhf42MYaNzNRGqKeHcozdTdAE4pYRs6HZRtTjsKXVs-X7bdXZc5buSfmx&gsc=ZLrN-hYAAADa-Gv9Ks2XMOgzLJv7pK84u4w3FxcUuKmQnM9jeHwPGA .  It’s a odd looking link because it is on my Google Group.

                                                                                                                                Nathaniel

[Tom Rokicki]

Excellent! Have you timed how fast it is? How many kilobytes per
second can you read?
Can you write? Does it support SDHC or only SD? How about FAT32?

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[Nathaniel Lewis]

The answer to your SDHC question is yes. It can use SDHC cards up to I
think 32GB. It worked with my 8GB SDHC card and could read and write. The
code in the file I put a link to test the read, write, and folder creation
methods. It will create a directory called avr in the main directory of the
SD card if it does not exist and write a message to /avr/info.txt. If
/avr/info.txt exists it will read the contents to the serial port. I have
not timed the interface but the site I got the code from claims that
interface works at 239 KBytes/sec write and 321 Kbytes/sec read on an
ATmega64 @ 9.21 Mhz

[Tom Rokicki]

That's pretty cool. I love SD cards; just a couple of pins and you've got
all sorts of storage for logging and stuff. And they are fast, and cheap.

On Thu, Nov 19, 2009 at 6:11 PM, Nathaniel Lewis

[Dave Curtis]

That's very useful, and something a lot of people want, including me.

I downloaded it, and the first thing I looked for is a license file. I
did not find that, but I found a copyright notice. I checked out the
URL, and again couldn't easily find the licensing associated with the
library you are using. After digging around on that web site, I found a
note that says "Freeware unless otherwise note." Ummm.... OK, but that
really doesn't cut it. elm-chan is being far too sloppy with licensing
and copyright, that will only lead to confusion and all-around sadness.

Every source distribution should have a copyright notice in every source
file, and some file that indicates the terms under which it is
available. It's not hard to do, and you should do that in your zip
file, and you should lobby the author of the code you are using to get
his ducks in a row also. That is to say, the source code bundle that
you download form him should clearly show the terms under which you can
use it.

I'd like to look at it further, because it is functionality that I've
wanted but never had time to pursue. It's not really useful to most of
us, though, unless the license is clearly spelled out.

-dave

Nathaniel Lewis wrote:
> I got an avr sd card reader/writer program working on the ATmega644! It
> even supports FAT though the ELM FatFs module (URL is in the main program).
> It should compile just fine under WinAVR and just redo the makefile and
> include a #define F_CPU 10000000UL in the main code for Mac and Linux. Here
> is the link for it is kind of large.
> http://the-linbot-project.googlegroups.com/web/FatFsSDC.zip?gda=V3Eriz4AAAAL
> x3cvYwaQyG90c_0UB0YzmCVJ5HuQhf42MYaNzNRGqKeHcozdTdAE4pYRs6HZRtTjsKXVs-X7bdXZ
> c5buSfmx

> <http://the-linbot-project.googlegroups.com/web/FatFsSDC.zip?gda=V3Eriz4AAAA
> Lx3cvYwaQyG90c_0UB0YzmCVJ5HuQhf42MYaNzNRGqKeHcozdTdAE4pYRs6HZRtTjsKXVs-X7bdX
> Zc5buSfmx&gsc=ZLrN-hYAAADa-Gv9Ks2XMOgzLJv7pK84u4w3FxcUuKmQnM9jeHwPGA>

> &gsc=ZLrN-hYAAADa-Gv9Ks2XMOgzLJv7pK84u4w3FxcUuKmQnM9jeHwPGA . It's a odd
> looking link because it is on my Google Group.
>
>
> Nathaniel
>

[Nathaniel Lewis]

I understand. I fixed it and added a License file. I has to do some
digging to find his, but I got it.
The new link is
http://groups.google.com/group/the-linbot-project/web/FatFsSDC.zip .
Nathaniel

-----Original Message-----
From: Dave Curtis [mailto:da...@dave-curtis.com]
Sent: Friday, November 20, 2009 10:41 AM
To: hbrob...@googlegroups.com
Subject: Re: [HBRobotics] AVR SD Card Reader

http://groups.google.com/group/hbrobotics?hl=en.