SD card MOD using different gpio

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Johny5
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Joined: 02 Dec 2009
Posts: 23

PostPosted: Fri Feb 19, 2010 16:52    Post subject: SD card MOD using different gpio Reply with quote
I'm using a linksys wrt54g v1.1 running dd-wrt v24-sp1 (I'm not home right now and I don't remember the specific version, but it shouldn't matter as this is a hardware question, not software). I'm out of space and need to do a sd card mod. The only problem is that all the instructions I've found for doing this use gpio 4, and unfortunately I'm already using gpio 4 for another purpose. I know that the gpio pins are somewhat interchangeable, but I'm curious if anyone has done this mod using differnt gpio pins?

Also, just a peice of info relating to the SD card mod that might be helpful to others doing the same...if you don't have a spare card reader that you are willing to take apart, you can use an old floppy drive edge-connector. The pins line up perfectly. See http://uanr.com/sdfloppy/ for more details.
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Johny5
DD-WRT Novice


Joined: 02 Dec 2009
Posts: 23

PostPosted: Sun Feb 21, 2010 2:04    Post subject: Reply with quote
My question was pretty basic, so I figured it out myself, and then some. Here is some info on the topic for anyone else that's confused.

First, there is a lot of good information at the following dd-wrt forum link, but gpio points are at least slightly differnt for every version of wrt, so always test them to be sure you are soldiering
to the right points.

Title: SD/MMC mod for the WRT54G-TM
http://www.dd-wrt.com/phpBB2/viewtopic.php?t=40464&postdays=0&postorder=asc&highlight

I ended up using ports 0, 2, 3, and 7. I didn't want to use port 0 since it is the wlan led, but I am already using gpio 4 for something differnt and I couldn't find gpio 5 despite hours of searching. I will eventually post pictures of the gpios for the wrt54gl v1.1, since none of the pictures I found online were of this particular router.

If you can't find pictures of your particular router the best way I've found to locate the gpios is to use the following code substituting the gpio fort for X. Then look for a square wave at soldier points on the board (blinking LEDs are a dead give away).

Code:
while true; do gpio enable X; sleep 1; gpio disable X; sleep 1; done


**credit for the code and idea to forum member moreins **

Also, once you get all the hardware completed and you are ready to use your SD card, make sure to format the card as ext3 before using it for the first time. I read several place that the router would format the card for you, but that didn't work for me, and after that my Linux machine wouldn't even recognise the card. I had to stick it in a Windows machine and format it as fat32 and then put it back in the Linus machine to format it as ext3. After I did that I put it back in the router an it worked perfectly, so to avoid all that headache, just format it as ext3 first.
olmari
DD-WRT Guru


Joined: 24 Oct 2006
Posts: 1447
Location: Vaasa, Finland

PostPosted: Sun Feb 21, 2010 13:39    Post subject: Reply with quote
Mine post is only slightly related, but I'd just want to point out that I'd use ext2 on flash-based devices, because journalling in ext3 writes frequently on the device, meaning it will wear out faster than when used ext2 that doesn't have journalling.

Now this might be about irrelevant issue in most modern flash-devices, but it's an old habit ^^

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Wolf Kodi
DD-WRT User


Joined: 13 Jun 2010
Posts: 126

PostPosted: Mon Jul 19, 2010 21:46    Post subject: Re: SD card MOD using different gpio Reply with quote
Johny5 wrote:

Also, just a peice of info relating to the SD card mod that might be helpful to others doing the same...if you don't have a spare card reader that you are willing to take apart, you can use an old floppy drive edge-connector. The pins line up perfectly. See http://uanr.com/sdfloppy/ for more details.


Instead of using a bulky floppy head or adapter, just buy one of a Micro SD card that comes together with an SD Adapter. Just solder wires on the SD Adapter itself.

Any luck finding the rest of the GPIOs? How many are there? I only know port 0,2,3,4,7 for WRT54GL v1.1
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