SD/MMC mod for the WRT54G-TM

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Doramius
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Joined: 29 Aug 2008
Posts: 311

PostPosted: Fri Nov 07, 2008 11:10    Post subject: SD/MMC mod for the WRT54G-TM Reply with quote
This mod may also work for some WRT54GL routers, as I followed information that was primarily written for modding the WRT54GL. Much of what I found came from [url=the-mesh.org]The Mesh Dot Org[/url] on this page: http://www.the-mesh.org/tiki-index.php?page=LinksysSDCard#Solder_points

[Click on images below to view larger image]


I'll mostly post pictures of the build I did. I had gone to Walmart and picked up a cheap Targus HighSpeed USB > SD/SDHC/MMC adapter. The case opened up really easy.

I went straight to work removing all components, except for the card slot, from the board. Solder braid works best, but even after I wicked off the leads to the chip, I still had to gently use a razor blade to slice under the leads to remove it. I also used a continuity tester to make sure there were no shorts from pin to pin. Pins 3 & 6 WILL short, but they are both Ground/Common. So no worries there.

Here's the pinout for the SD card and the GPIO points:

Now where the GPIO points are....? These little images made them quite easy to find. I still tested them to make sure they were correct. And they were.

However, Instead of the ground at the JTAG headers, I found and tested this large, unused, copper pad for ground. It's the middle pad that comes out to a 'T'. (arrow off to the right)

Now I had some ribbon cable left over from when I built my JTAG/TTL box.

I needed to mount the SD slot somewhere and chose over ports 1&2, as the bracket served as a nice size mounting point. I lightly sanded the top, so it would take solder. And then placed the SD slot between to place solder at points for a hold-down.

I then soldered the ribbon cables to the SD slot pins on the top of the mini-board. Not an easy job as they are pretty small. Next I took a piece of thin double sided tape and placed it on the bottom of the mini-board the SD slot was attached to. This did 2 things. Kept the port bracket from shorting the pads on the mini-board and stuck the board to the bracket. {Note} make sure your mini-board is not all the way to the other edge. You should be about 2mm from the edge as the case will slide about that distance over the edge of the bracket. I then took 2 solid strands from a twisted pair cable, stripped them, twisted them together, and soldered them together. This was my hold-down. I soldered the inside first, placed the mini-board on the bracket, and then soldered the other end at the edge of port one on the bracket. I left a bit of a tail so I could use pliers to pull the end firmly down to make sure it would solidly hold the slot in place. Sliding the cards in and out can cause quite a beating. The double sided tape and the hold-down will make sure the slot stays firmly affixed.

I then soldered the points as shown. Also note, that there are through-hole points near the LEDs. Use those as you don't want to remove an LED, or cause any damage to them. It also keeps the wire underside as some cases have plastic parts that mount right over the LEDs.

Next I brought out my trusty Dremmel and, after careful measurement, cut out the slot in the case where the card would go in. I made the slot about 2mm wider than the card on the sides. Giving a 1mm space on either side.

Time to put it all together.

Now that it's all done, physically, it's time to plug in an SD or MMC card and test it out with a PC.
When I first plug it in, I notice it takes a little longer to load this first time. The SES light may or may not come on and flash a few times. This is normal. Just wait for the Power, Wireless, and the port light, corresponding to the port your PC is connected to, are all on and steady. If the SES light came on, with for it to steady. Log into the DD-WRT page. Go to the Administration tab and scroll down to MMC/SD Card Support areas. Enable it. I left the GPIO pins select at auto and it worked fine, but if you need to, the GPIO points are listed above. I also enabled the JFFS2, and you can also enable CIFS Automount, if desired.

Once you apply the settings, let it complete to reload the page. it may take a few minutes. The page may come back with data missing. Again, this is normal. Go to your router and press and hold the reset button for 30 seconds, while still holding the reset button, unplug the power and wait 5 more seconds before releasing the reset button. Now plug the power back in and let the unit load.

Again, this may take a few moments as it formats the card. The SES will probably come on, and rapidly flash for a bit, then turn solid. Wait for the Power, Wireless, and the PC connected port light to come on, steady. Now log back into DD-WRT and check the status. Any enabled items should show space usage listed.

The default for DD-WRT is 4096KB. There's a way to change it for 1GB cards, but I haven't had a chance to do it yet. When I do, I'll amend to this tutorial.

Enjoy!


Last edited by Doramius on Sat Nov 08, 2008 2:31; edited 2 times in total
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Shawn360
DD-WRT Guru


Joined: 26 Jul 2008
Posts: 1237

PostPosted: Fri Nov 07, 2008 11:39    Post subject: Reply with quote
Why not use the ground at the serial header?
Doramius
DD-WRT User


Joined: 29 Aug 2008
Posts: 311

PostPosted: Fri Nov 07, 2008 16:35    Post subject: Reply with quote
I'm trying to find alternative points to the headers. This way I can still use a JTAG or serial header. I'll probably update the 3.3V wire at a later time, but as you can see, locally I finished this project about 3am.
jmh9072
DD-WRT Guru


Joined: 04 Sep 2007
Posts: 800
Location: Ohio

PostPosted: Fri Nov 07, 2008 16:37    Post subject: Reply with quote
That's awesome! Great job!
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gix
DD-WRT Novice


Joined: 23 Aug 2008
Posts: 18

PostPosted: Sun Nov 09, 2008 9:59    Post subject: Reply with quote
shouldnt it look more like this?


Doramius
DD-WRT User


Joined: 29 Aug 2008
Posts: 311

PostPosted: Sun Nov 09, 2008 11:47    Post subject: Reply with quote
I grabbed the snap shot with just the adapter installed. I had a Micro SD and the SD adapter and forgot to insert the micro card. You can see that in one of the pictures. Embarassed
Erich2050
DD-WRT Novice


Joined: 10 Feb 2007
Posts: 7

PostPosted: Mon Dec 01, 2008 6:01    Post subject: Reply with quote
i tried to format my sd card on my debian system, because my wrt54g wasn't able to do it by itself. so i typed ...
Code:
umount /dev/sdc
mkfs.ext2 -L sdkarte /dev/sdc

... everything looked fine on debian and so i pluged my sd card into my router to see if it works. but it did't :(

i used the micro sd card of my nokia 6300 with an adapter

what could i made wrong?


sry for my bad english Confused



InternetPCN - Router Status_1228110359455.png
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InternetPCN - Router Status_1228110359455.png



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Doramius
DD-WRT User


Joined: 29 Aug 2008
Posts: 311

PostPosted: Mon Dec 01, 2008 16:58    Post subject: Reply with quote
On some of those micro cards, I am not sure if the drivers are properly recognized. I had some issues with some micro cards too. I had initially tried a Patriot 1GB micro SD card with an adapter, but it wasn't working and I got various results. Do not use anything larger than 1GB, as those do not seem to work either. I used a PNY SD card and that worked.
grantch
DD-WRT Novice


Joined: 17 Dec 2008
Posts: 10

PostPosted: Wed Dec 17, 2008 18:26    Post subject: Reply with quote
I had the same issue with my mod. My 2GB MicroSD card with adapter and it always showed up a 2MB or 4MB but it actually was not mounted at all. Using dmesg showed the mmc was not detected. I had an old 32MB card that I put in and it worked with no problem and DD-WRT showed 27 MB free. I read somewhere that someone changed from a 1A power adapter to a 5A one and the bigger cards worked.

Grantch
trilith
DD-WRT Novice


Joined: 10 Oct 2008
Posts: 20

PostPosted: Wed Dec 17, 2008 18:53    Post subject: Reply with quote
grantch wrote:
I read somewhere that someone changed from a 1A power adapter to a 5A one and the bigger cards worked.

Grantch


hmm, care to elaborate ? are you referring to the AC power adaptor of router ?
grantch
DD-WRT Novice


Joined: 17 Dec 2008
Posts: 10

PostPosted: Wed Dec 17, 2008 19:29    Post subject: Reply with quote
trilith wrote:
grantch wrote:
I read somewhere that someone changed from a 1A power adapter to a 5A one and the bigger cards worked.

Grantch


hmm, care to elaborate ? are you referring to the AC power adaptor of router ?


Yes the AC power adapter

Here is the post
https://dd-wrt.com/phpBB2/viewtopic.php?p=59574

Grantch
Here also is a post from someone having problems with WRT54G-TM over 64MB

https://www.dd-wrt.com/phpBB2/viewtopic.php?p=193994

This is essentialy the problem I had although I only have a 32MB and a 2GB to try
Doramius
DD-WRT User


Joined: 29 Aug 2008
Posts: 311

PostPosted: Wed Dec 17, 2008 21:38    Post subject: Reply with quote
You're not really changing the voltage, but increasing the amperage that can be used. This is understandable. Some flash cards over 512MB require a little more amperage. Some slower cards might not. Some routers are even coming with 500mA power supplies. Without any mod, I've noticed those burning out quite easily. The 1A adapters may not have enough juice to support the larger draw of current.
grantch
DD-WRT Novice


Joined: 17 Dec 2008
Posts: 10

PostPosted: Wed Dec 17, 2008 22:04    Post subject: Reply with quote
Correct I just need to boost the avaiable current and not change any voltages. I think mine came with a 1A power supply. Does anyone know if these power supplies can be modded, or what mechinism they use to limit current? When you say they burn out do you know what componant fails in the AC supply?
Doramius
DD-WRT User


Joined: 29 Aug 2008
Posts: 311

PostPosted: Wed Dec 17, 2008 23:45    Post subject: Reply with quote
It's usually the transformer itself. The transformer is wound to appropriately step down the voltage and current. Sometimes there's a resistor and capacitor to help filter a bit before the bridge to convert to DC, and those are known to fail at times, but aren't usually the problem. What happens is if there is too much current draw, the unit literally burns out. It's like forcing a horse to run it's fastest, constantly, without giving it a rest....and then trying to push it faster. By limiting the Amperage, it limits the modding to their devices. Almost like why they keep reducing the flash and RAM in their devices.

All you need is a 12VDC power supply that has a rating of 5A or more (5A is sometimes shown as 5000mA for those that may not be as technically inclined). A device will only use the current it requires. So if you get a 12VDC power supply with a 20A rating (it'll be a large looking block for that kind of amperage too), if your device only requires 2A, it'll be fine using the 20A power supply. If the device requires 3A, and you use a 500mA power supply, then you'll either burn out the power supply, the device won't have enough current flow to work, or both.

FYI - Generally, the smaller the amperage a power supply supports, the smaller the power supply will be. The more amperage a power supply supports, the bigger the power supply tends to be.

Here's one more snippet of advice. PC power supplies tend to have their 12VDC rails run somewhere between 10A-20A. Some of the MUCH older PSUs may not need to be connected to a MoBo to turn on. Most ATX PSUs require some sort of connection to power on. I don't remember the pins to short a resistor across, but you could get a Cheap PSU tester for $15-20 and connect it to an old PC PSU, to give you a nice 12VDC with enough amperage. Might even be able to power a few other devices too. I have a PSU that I added USB ports connected to the 5VDC line to charge an iPod & iPhone.

I know someone else who used a PC PSU to power an HO scale model railroad. I didn't know that was possible, but pretty cool ingenuity.
moreins
DD-WRT User


Joined: 18 Nov 2006
Posts: 320
Location: Cali, Colombia

PostPosted: Thu Dec 18, 2008 3:22    Post subject: Reply with quote

thanks for this. i will give it a try tomorrow and see what happens.

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PPTP, WDS link and SD Mod
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