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How To Debrick Your NETGEAR WNR3500L Using A USB-TTL Cable on Windows (Page 2 of 2)


Step 6: Modify the USB-TTL Cable for Use with WNR3500L

Take a look at the photo above.  See how each of the leads is covered by a small plastic tab?  Bust out your tiny screwdriver or whatever it is that you have that's tiny, and pry off the tabs on the black, yellow, and orange leads only.  If you choose to remove all six, you will need to wrap up the unused leads in electrical tape to avoid shorting anything out.  I just left the unused leads inside the plastic harness as shown above.  Once you pry the tabs off, the leads that you will use slip out easily. Now, you can plug the cable in.

Step 7: Find Out What COM Port Your Cable is Using

You installed the cable driver in step 3, right?  If so, head on over to Control Panel => System => Hardware => Device Manager, and click on the "Ports" item as shown in the photo above.  Note the "USB Serial Port" item with a designation of "COM3."  You'll use this information in the next steps. If you don't see that, plug in the cable and the Device Manager should refresh.

Step 8: Connect the USB-TTL Cable to the WNR3500L

Note: Make sure the router is still powered off and unplugged from power when you do this.  Don't touch anything metal either, don't want to take any risks of shock or shorting anything out, which is always a potential concern when tinkering with open electronics.

This part is particularly important, as if you don't connect these cables properly it will be very frustrating for you!   Take a close look at the photo above.  On the pinout on the board, you will see six pins.  Next to one pin it will read "JP1."  That is actually Pin 6.  Pin 1 is labeled with a "1" next to it.  Connect the cables as follows and as shown in the photo:

Black => Pin 6 (next to JP1)

Yellow => Pin 5

Orange => Pin 2

Note: In this photo, the black and yellow leads are seated properly.  I wanted to show you what an improper cable seating looked like; the orange cable is NOT seated properly.  Make sure all the cables are firmly seated to the pins and that they are not touching each other.

Step 9: Configure and Launch PuTTY

Hanging in there?  Do you feel like a geek yet?  It should feel good :)

Fire up PuTTY and you'll see the screen above.  Select the exact options as shown above; click on the Serial radio button, the port to COM3 (or whatever port was revealed in Step 7) and the speed to 115200.

Then, click on the very last item in the menu and choose the options above.  They must be exact: serial line of COM3, speed of 115200, Data bits of 8, Stop bits of 1, and "None" for both parity and flow control.  Once you are confident these settings are correct, click "Open," and you will see a blank window with a green cursor.  Nothing is supposed to be happening in there yet, so don't fret.

Step 9: Power on the WNR3500L and Press Ctrl-C

Now, you can finally connect power to the router.  Press in the power button and immediately press Ctrl-C on your PC, with the PuTTY window active.  This will bring you to what is called the CFE console; essentially, you're interacting directly with the board.  If this does not happen, double and triple check all of the previous steps.

Then, type in "tftpd" (without quotes) to bring up what is called the TFTP interface.  This will ready the router for programming.  If this step performed properly, you'll be left with the screen above.  Almost there...

Step 10: "Put" The Firmware Into Your WNR3500L In The DOS Prompt

Note: If you are on Windows 2000, XP, or 7, you have a TFTP client built in.  However, if you're on Win95, 98, Me, NT, or Vista - you do not.  

Instructions for installing TFTP on Windows Vista can be found here.

Here is one open source TFTP client for Windows that you can try.

Assuming that you have TFTP installed in some form, zoom on over to your DOS prompt. You copied the original NETGEAR fimware to your C: drive, correct?  Good.  Type "cd.." without quotes as shown above to get to your root directory, then type this command:

tftp -i 192.168.1.1 put FIRMWARE_FILE.chk

When you do this, the TFTP command will send the firmware file you indicated to the router, and you will get a confirmation as shown above.  If this doesn't work, make sure your router is connected to your PC properly, you have a static IP that doesn't end in 1, and that you can ping the router.

If this command is successful, your PuTTY console will start to get some action, and it will re-program the router.  Allow this process to finish, it will take several minutes, and wait until it is COMPLETELY finished or you will get a bad flash.  And nobody wants a bad flash!  You'll get a lot more text than is displayed above, but when it's done, you can try accessing your router's GUI via http://192.168.1.1. You will need to enter the "standard" username and password, consult your user manual for this information. (At the time of this writing, "admin" and "password" were used.)

Step 11: Rejoice and Relax... or troubleshoot

Hopefully, not the latter, but unfortunately things don't always go as planned.  If you're struggling with this procedure, have an unsolvable problem with your WNR3500L, or are on another OS let us know.  We're continuing to work on recovery guides for Linux and Mac OS X, so stay tuned!

You can post your questions on the public forums or as a comment below!

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Tags : debrickrecoverrestoreserial consoleunbrickwnr3500l

Discussion:    Add a Comment | Comments 1-25 of 169 | Latest Comment | 1 2 3 4 5 6 7 Next »

October 5, 2009 12:46 PM updated: October 5, 2009 12:47 PM

It would be nice if you update this article with a link where "tftpd" can be downloaded.

Thx

October 5, 2009 12:48 PM updated: October 5, 2009 12:49 PM

Am I missing a link somewhere? I have included links to the cable purchase, original firmware, PuTTY download, and other WNR3500L articles. Not sure what else you might need :)

*Edit* The OP's post was edited to include a request for tftpd.

Most versions of Windows have tftp built in, from what I understand.

If you do not have it, here's a link to an open source TFTP server for Windows. I haven't tested it, though, so I'm hesitant to include it in my article as a "de facto" solution.

http://tftpd32.jounin.net/

Peter Redmer
Administrator
Blog | Twitter

October 6, 2009 2:45 PM

*** Deleted By Moderator ***


October 6, 2009 7:14 PM

Peter Redmer said:  Most versions of Windows have tftp built in, from what I understand.

A tftp client is included with Windoze 2000, XP, and Win7.  It is NOT included with Win95, 98, ME, or NT.  For Vista, tftp is in the install CAB, but not installed by default.  Instructions at:

http://www.simplehelp.net/2008/09/10/how-to-install-a-tftp-client-in-windows-vista/

One problem with many tftp clients is the inability to deal with a login and password.  If that's an issue (not in this case) use the Cisco-Linksys tftp client:

http://downloads.linksysbycisco.com/downloads/Tftp,0.exe

October 6, 2009 8:56 PM

Thanks Jeff for your help - especially for the link on installing TFTP in Vista. I'll edit the article to add that in.

Peter Redmer
Administrator
Blog | Twitter

October 7, 2009 2:30 AM

There's a much safer way of modifying your USB-TTL cable - I do it all the time with front panel connectors in PC cases.

Instead of completely ripping off the little plastic tabs which hold the sockets in place, just slightly lever them up (I usually just use a pin but a tiny screwdriver might also work) and then slide the wire and socket out.

Then you can rearrange the pins as needed, slide them back in and not have them standing bare out in the open and a potential short circuit risk.

Any pins you aren't using can be wrapped in tape to prevent shorts.

October 7, 2009 10:59 AM

Thanks Agent24, I was unaware that the tabs could just be lifted and not removed. Perhaps I wasn't careful enough, but I couldn't seem to get them to move without breaking them!

Peter Redmer
Administrator
Blog | Twitter

October 7, 2009 11:46 PM

Yeah they usually only need to be lifted slightly, 1mm or so.

I find a pin or needle works the best

Then again perhaps the plastic used to make the one you have is more brittle..

October 16, 2009 7:06 PM

Hey, nice article! A comment and a question:

IRT the your TTL-USB cable, check out these male-to-female jumper wires at the Sparkfun link below. I use the exact same USB-TTL cable on all my routers...but since the pin-outs are not standard, these little jumpers keep me from destroying my $20 cable!

http://www.sparkfun.com/commerce/product_info.php?products_id=9385

The question - was the pin headers already in place or did you have to install them? It would be interesting to know if Netgear installed those from the factory..

Thanks!

October 18, 2009 3:46 PM

Gratefully, the pin headers were pre-installed from the factory :)

Peter Redmer
Administrator
Blog | Twitter

December 21, 2009 3:34 AM

I recommend getting the http://se.mouser.com/ProductDetail/FTDI/TTL-232R-3V3-AJ/?qs=sGAEpiMZZMvYU0Oh5... cable. It is FTDI Model TTL-232R-3V3-AJ

It's MUCH more durable than the one you use/recommend. I create a bunch of labeled headers soldered an audio jack or install the audio jack on the side of the router for easy access to the CFE.

December 24, 2009 1:16 AM

Hello,

Does this also solves the issue with the custom loaded firmware from a provider?

This because I'm arguing with my provider about the custom loaded firmware they have put on my router and that's quite wordless. This due the fact the update button is missing. So I will never be able to update the router unless something special will happen to my router WNR3500V2.

Please can someone help me out?

I do hope so.

Thanks in advance.

December 26, 2009 4:57 PM

If your router does not support firmware upgrades through the web interface you should be able to do it this way instead.

However, it may be possible they have not only customized the firmware but also the hardware as well...

January 9, 2010 12:14 AM

I just got a new 3500L last week.
After taking off the cover I found that Netgear decided to not install the pins on the board. They just soldered up the holes where the pins are suppose to be.
You might want to update the article to let people know the new ones have no pins.
Guess its time to learn to solder.

January 12, 2010 10:17 AM

The article has been updated to reflect that production models of the WNR3500L do not have pinouts preinstalled. Hopefully, this will resolve confusion!

Peter Redmer
Administrator
Blog | Twitter

January 12, 2010 10:34 AM

Update: I have heard that NETGEAR has been listening to posts on the forum and that the pinouts will be added on future production models as soon as possible. Look for an official post on this soon.

Peter Redmer
Administrator
Blog | Twitter

January 13, 2010 10:51 AM

Hi everyone, i 'm posting because my firmware update on my wnr3500l completely failed. So the last solution for me is to debrick my router. Can anyone tell me if it's not better to buy a "TTL-232R-3V3-WE" cable instead of a "TTL-232R-3V3" because a "TTL-232R-3V3-WE" cable has no connector at serial end ?
thanks for reply

January 13, 2010 5:21 PM

fabien,
What firmware did you have on it and what did you try to upgrade to?
Can you Ping the router at all?

Regarding what you buy. Do you know if your router has the pinouts?

BC Support, Design and Development

January 13, 2010 11:59 PM

Hi, I had dd-wrt V24 SP1 on my router and I wanted to upgrade to the Tomato Firmware.
I tried to ping my router, no answers from the router.
I tried to telnet my router, it fails.
I tried to use the recovery tool on the disk given with the router, it fails.

And at last, my router hasn't the pinouts.

January 14, 2010 1:52 PM

fabien,
Do you have your computer setup to obtain an IP address automatically?
If you do then, and this is a slim chance, you may be able to set your computer up to use an assigned address like 192.168.1.10 and your gateway to 192.168.1.1 and then be able to ping the router.

If your router is bricked and won't load sometimes it will stop and run the CFE prompt and you can TFTP a file to it.

BC Support, Design and Development

January 14, 2010 4:20 PM

Thanks BrandonC, I always have my computer setup with a fixed IP address like 192.168.1.2
I tried to get a dynamic IP adress form the router, but Windows 7 says there's no connection between my pc and the router, I got a yellow triangle, with an "Exclamation mark" inside, on the link between my pc and the router.

Next Monday, I'll buy the cable to debrick the router.
I will try with the tool on the Netgear cd once or twice again.

But I read that if the firmware was corrupted, the power light on the front of the router should be blinking fast, on my router it's solid amber as if the router was performing power-on self-test diagnostic. Is my firmware really corrupted !!!!

Maybe I should let it plugged all night long and maybe tomorrow morning, I would have a good suprise.

January 15, 2010 6:36 PM

My guess after leaving it plugged in is that it is still the same. :)

BC Support, Design and Development

January 24, 2010 12:14 PM updated: January 24, 2010 3:34 PM

Hi,
I tried to debrick my router, but it gets stuck at this point:
Starting program at 0x80001000

I can't get to the CFE console, here's the complete message:

CFE for WNR3500L version: V1.0.0.88
Build Date: Fri Jun 12 11:11:15 CST 2009
Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
Found a 4MB ST compatible serial flash
et0: Broadcom BCM47XX 10/100/1000 Mbps Ethernet Controller 5.10.56.28
CPU type 0x19740: 453MHz
Tot mem: 32768 KBytes

Device eth0: hwaddr 00-26-F2-68-1A-16, ipaddr 192.168.1.1, mask 255.255.255.0
gateway not set, nameserver not set
Checksum mismatch:
Image chksum: 0x00000000
Calc chksum: 0x02C0010E
Loader:raw Filesys:raw Dev:flash0.os File: Options:(null)
Loading: .. 3768 bytes read
Entry at 0x80001000
Closing network.
Starting program at 0x80001000

How much time does it normally take to access the CFE ?
I've been waiting for 30 minutes and it still shows:"Starting program at 0x80001000" !!!

January 24, 2010 5:34 PM

You have to hit "Ctrl-C" right when you are booting and see something in the console. Might have to hit it several times to catch the right spot.

BC Support, Design and Development

January 25, 2010 12:31 AM

I've been doing this several times and nothing happens. I also tried to plug the router in while pressing the reset button with the putty window active. It still hangs at "Starting program at 0x80001000"

I don't know what to do now except trying again and again and again.....

Discussion:    Add a Comment | Back to Top | Comments 1-25 of 169 | Latest Comment | 1 2 3 4 5 6 7 Next »

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