I no longer involve myself with WRT54G development (hardware or software). I have gone from being a pseudo-developer to a simple end-user by choice. The below content still applies to certain WRT54G models (as of 2005/02/06), and the modification still works. I do not wish to be contacted about this pages' content; everything you need to know about this mod is here, and other information can be found elsewhere.
The following are instructions for modifying your WRT54Gv2 or WRT54GS unit to support a single serial port. Most of these instructions correspond directly with Rod Whitby's Dual Serial Port Mod, but differ in a few minor respects. I'd like to take a moment to thank Rod for providing instructions (and photos) on his site -- without his modification, none of this would exist. Thanks Rod!
Please note that THIS MODIFICATION WILL NOT WORK ON WRT54G V1.0 OR V1.1 UNITS. There is no serial port header provided on the PCB; it's recommended you return your WRT54Gv1 unit to wherever you bought it and get a v2 or GS. Do not bother opening up your unit; just do as you're told. ;-) If you don't know how to determine what version of WRT54G you have, turn the unit upside down and look for the version number.
Finally (and this should go without saying): YOU WILL VOID YOUR WARRANTY BY FOLLOWING THIS PROCEDURE! You've been warned.
Rod's instructions are fantastic for most people, but I had no desire to have two serial ports on my WRT54GS. The DB9F would suffice; I just wanted a simple serial console. After reviewing his mod, I concluded what needed to be changed to make things work with only a single DB9F. I also opted to change things around to make them more "modular", in the sense that the AD233BK could be re-used at a later date, as well as idealising a situation where the serial port goes bad or something of that nature.
The primary differences are the following:
|AD233BK||233A Serial I/O Kit w/CTS-RTS|
|DSUBPCSF9||9-pin female PC straight connector|
|IDCMH10||10-pin shrouded male IDC header|
|IDDC10||10-pin contact female IDC socket|
|POLHDCON6||6-pin header connector|
|PLHDPIN||Crimping pins for POLHDCON6 (includes 10 pins)|
|MCCABLE10||10-pin flat ribbon cable (multi-colour)|
|Soldering pencil, or soldering iron with small/defined tip|
|640-0025||Lead-free solder; 0.032" diameter|
|640-2090||OPTIONAL: Desoldering braid (copper-based)|
|Wire strippers, scissors, or strong fingernails|
|Needle-nosed pliers, or something very similar (for crimping)|
The total cost of all the part-numbered items should come to approximately US$30.00 or so.
The links I've provided reference COMPSys (the AD233BK kit), Futurelec (one of the few companies that supports hobbyists), and the infamous Radio Shack (not a place I commonly recommend, but suffices for this project).
If you can find some of the above parts locally, then by all means purchase them there. Support your local economy if possible. The only piece I recommend purchasing regardless is the AD233BK kit from COMPsys. It's an absolute pre-requisite; and besides, Ranjit is cool.
A note about the AD233BK kit: there are multiple revisions of this kit. Assuming you buy the kit directly from COMPsys, you should receive a Revision 4 or later model. Previous revisions (Ver3 and below) will require modified instructions (not provided here).
If you do not own a soldering pencil or soldering iron (a soldering gun will not work; the tip is too large), I recommend Cooper Hand Tools' Weller WESD51 soldering station. Yes, it's expensive (approximately US$100.00), but sports replacable/exchangable tips, and will last you your entire lifetime. If you plan on doing electronics projects in the future, it's a good investment. Otherwise, you can pick up a cheap soldering iron from Radio Shack or some such place; just be sure to get something that has a 1/16" tip.
If you have no idea how to properly solder, I recommend reading The Idiot's Guide To Attaching A Modchip, which despite being completely unrelated to this project, includes descriptions as well as images of where to place the tip when soldering AND desoldering. You can also use Aaron Cake's "How To Solder" guide if the aforementioned doesn't suit you. If you don't trust your capabilities, I recommend either taking the plunge and giving it a shot for the first time, or getting someone else to do it. I'm alright at soldering (it's not something I do very often), and I had absolutely no problem completing Rod's recommended procedures; things worked the first time. If you're still wary, buy multiples of some of the above parts, and also get a desoldering braid (you can fix your mistakes).
To be written...
Admittedly, my first attempt at all of this did not come out as "clean-looking" as Rod's rendition. The reason for this is that the DB9F connector included with the AD233BK kit is pre-assembled; it cannot be easily "front-mounted" (as shown on Rod's site). This is why Rod used an external DB9F. I chose to use the DB9F that Ranjit includes with his kit.
Regardless, the following are pictures of my first single-port mod. The instructions I've provided here do not match up with the pictures provided below! I've since changed the procedure a small bit, and plan on deploying the changes on my WRT54GS when I have the time. The pictures will still show you what I've done, and prove that it works just fine.
More pictures will follow, as well as a re-shot of DSC00003.JPG (since it's slightly blurry).