Modding the Linksys WRT350N v1


Do not attemp to do those mods yourself unless you are knowing what you are doing! Seriously man, you can damage your hardware and you will lose your warranty!
No matter what happens after you modded your Router, I am in no human imaginable way responsible for it!
Do it at your own risk!
It may fry your cat (I am not promising it that it will!), eat your goldfish, drink your beer or sleep with your wife, just be aware.

Adding a Serial Port

(to recover from bad flash, d'oh!)

I was playing around with one of my WRT350N, actually that is what I do most of my freetime. Then suddenly, after about 50 successfull ones, the flashing of the firmware went wrong. Too bad...
The problem was that boot_wait was disabled, and not enough, even some other mess was around that after enableing boot_wait I still could not flash via tftp.

Linksys WRT350N Serial Port Pinout
The pinout of the serial is the same as for most linksys stuff... The wrt54g-series have it that way, or if they have two of them they are just doubled up...

Linksys to MikroKopter Serial Adapter
Here is a simple adapter from the Linksys Pinout to to the one used by MikroKopter for their serial communication, the USB adapter is also available there. I have a lot of MK-Stuff around so it is somewhat handy to adapt other stuff to their pinout :)

You will still need a level shifter from TTL Level to PC-Port-Serial, but that is common for such devices. Look around for information about adding a serial port to an WRT54G, it is exactly the same stuff you need... I took a MAX3232, five 0,1µF capacitors and some wires of course... works smiley
Any old USB->Phone cable (for example siemens is known to work well and the pinout is well known as well) will do the job. They have ttl-level as well so no need for extra parts. You can get them for below five bucks and they do their job... Using it, really rocks :)
Some solutions are listed here: OpenWRT - Serial console

If you get it then open serial connection and press Ctrl+C during bootup, you will end up in CFE.
there you will have to
nvram set boot_wait=on
nvram commit
and see if it gets pingable again during boot (only for 3secconds, so like always, connect it to a switch, ensure your pc has got 192.168.1.X as ip and do a constant ping [normal in most *nix systems, -t for windoze])
if it is then try uploading firmware the normal tftp-way.
If it ends up in some errors in the serial console about the flash not being verified/corrupted than try
flash -noheader : flash1.trx
and tftp imidiatly after typing it... But: Check the image you are flashing!

helps a lot where linux is around :)

Worked for me.

Something important: Speed is 115200 bits per second!!!

Serial Port Settings

Bootup till CFE (press Ctrl+C to interrupt):

OpenWrtDocs/Troubleshooting helped a lot!

Adding a seccond USB Port

(there are the lanes, so use them... like on the Autobahn!)

You need to solder 4 (four!) bridges to have the USB stuff at the second port, not much to do, huh!?
Lets start:
Linksys WRT350N Second USB MOD Solder Points for first Bridge
This is the firs pair of bridges you have to solder, the easy ones :D

Closeup of the first pair of bridges
Closeup of the first pair soldered
Sorry, Powershot S40 by Canon is not that goot for such pics... Especially when you do not have a display to check what you made and not software for remote capture...

Linksys WRT350N Solder points for second bridge
This is the hard part, you will need to solder two bridges from the outside of the metal-frame to the inside, not much space, but it can be done, at least I did it smiley
I used a single wire from a cable, put a bit solder on it, put it through below the metalframe and soldered it to the inside point.
Then pulled a bit to test if it is really soldered, got a lens and checked it again.
After that I cut it off just over the point on the outside and solderer it there. Took the lens again and checked it.
Got the multimeter and measured from the USB-Port to the inside point.
And of course checked that the wires do not get to the metal frame as it is grounded!
Test your soldering using a multimeter at least a dozen times! Be sure you know what you are doing!
(In case you know Cox: Oh god Cindy, you have to check it and check it and check it and check it and check it...)

Second pair of bridges closeup
here is the second pair of bridges soldered, actually you can only see a part of them... Ugly, I know...

Linksys WRT350N first test with both usb ports
First test and wow, the webcam and the harddisk work at the same time, impressing smiley

Linksys WRT350N backside without metal housing
The backside of the device with the metal-housing/shielding removed, needed it removed to track the USB-Data-Lanes.

Linksys WRT350N reassembled working with two usb ports
Finally reassembled the stuff, looks somehow ugly but cutting plastics is not my strength, so I chose the pic with the connectors already in smiley

Linksys WRT350N telnet after loading two usb devices
Finally telnet into the device and see what we have got... NICE!

Another test using two 2.5" USB Harddisks attached to the WRT350N. The firs measure was during a second hdparm on another console, same partitions, just vice versa...
Actually the firs one is a really old 30GB disc that has been on duty for four years in my old Acer Aspire 1310, it was slow ever but think it is okay for a router.
Something useful for DD-WRT and USB: Unofficial USB support Images

How to disassemble a WRT350N

Cool mods, but how to I open the damn thing without using a chainsaw?

Popup backsides
First of all popup the backsides. They are only snapped in. Must use a bit of strength but will pop-up. Then you can easily pull them to the back. Remove the two silver-colored plasitcs that way.

Remove the front by squeezing the clamps
Remove the front by squeezing the clamps.

Remove those four screws
Remove those four screws.

Thats all. Now you can remove the top plate and take out the main pcb...

Kiel the 14th of August 2007 | This page at least tried to be valid XHTML 1.0 Transitional!