The WRT54GC is the 'Compact' version of the WRT54G. It has a built-in antenna as well as an SMA antenna connector instead of RP-TNC.

The Linksys WRT54GC is an ADSL gateway with wireless acccess point integrated.

Version/Model	Launch Date	S/N	OpenWrt Version Supported	Model Specific Notes
WRT54GC		-	-	-
WRT54GC v2		-	-	non-detachable external antenna
WRT54GC v3		-	-	-

NOTE: …

OEM source code may be available at: http://support.linksys.com/en-eu/gplcodecenter

SoC	Ram	Flash	Network	USB	Serial	JTag
@ MHz	4MiB	1MiB	4 x 1	No		Yes

Manufacturer's site: http://support.linksys.com/en-eu/support/routers/WRT54GC

Forum: https://forum.openwrt.org/viewtopic.php?id=19466

Front:

Back:

Note: This will void your warranty!

Having spent about seven hours trying to take the thing out of its case, here's what I found out:

• There's a screw! On the back side with the rubber feet, towards the bottom of the bottom-left foot (next to the FCC and "Power: 3.3V 2A" sticker) is a small Philips-head screw.
• The rest of the case is held by plastic tabs. They come apart with some force, but be gentle: the plastic feels weak.
• Once the back cover is off, you're almost there. There's two screws that hold the PCB on, also Philips-head. The sticker on the side holds down the ethernet ports, so it must (sadly) be removed. Also, don't forget to disconnect the external antenna connector by removing the nut, and then the antenna selector switch by just pulling it out of the board.
• Smile and be happy.

Main PCB

→ port.serial general information about the serial port, serial port cable, etc.

How to connect to the Serial Port of this specific device:

→ port.jtag general information about the JTAG port, JTAG cable, etc.

JTAG port on WRT54GC v3 could be the unpopulated 12 solder-point group labeled JP1.

How to connect to the JTAG Port of this specific device:

 __ANTENNA___________
|                    |
|                    | P
|                    | O
|                    | R
|1 _ 16              | T
| | |<--JTAG         | S
| |_|   Solder Pads  |
|8   9               |
|____________________|
      1  ->  GND
     10  ->  RST
     11  ->  TDI
     12  ->  TMS
     13  ->  TCK
     15  ->  TDO

More stuff about the router:

• The chip that's unrecognizable in the FCC photos has been identified as Macronix FLASH, 8MB. See the full PDF at here (PDF). Very detailed. Thank you, Macronix. Now if only you were easier to find… P.S. Thanks to for ID'ing manufacturer.
• The power LED actually has two LEDs in one package: an orange and a green.
• There doesn't appear to be JTAG, but there is a solderpad area. I'll test it for serial, but for now is classified as "unknown". Pin 11 seems to have some plusing output by the piezo buzzer test. I'll dig up some MAX233's and see what it says.

Pictures and more information available on my website: http://yasha.okshtein.net/wrt54gc/.

I really like this device: it's small and uses only 3.3v. I'd really love to get OpenWrt on it, possibly for a future version of my Wifi Car. Any takers? The router is quite cheap at $39 (i got it for $29 on Black Friday), but at that price, most users would opt for other, fully supported, routers.

Little test :

chtitux@localhost ~/src $ nmap 192.168.2.1  -p 80 -A

Starting Nmap 4.01 ( http://www.insecure.org/nmap/ ) at 2006-06-10 19:15 CEST
Interesting ports on 192.168.2.1:
PORT   STATE SERVICE VERSION
80/tcp open  http?
1 service unrecognized despite returning data. If you know the service/version, please submit the following fingerprint at http://www.insecure.org/cgi-bin/servicefp-submit.cgi :
SF-Port80-TCP:V=4.01%I=7%D=6/10%Time=448AFE26%P=i686-pc-linux-gnu%r(GetReq
SF:uest,8A,"HTTP/1\.0\x20401\x20Unauthorized\r\nServer:\x20IP_SHARER\x20WE
SF:B\x201\.0\r\nWWW-Authenticate:\x20Basic\x20realm=\"WRT54GC\"\r\nContent
SF:-type:\x20text/html\r\n\r\n401\x20Unauthorized");

Is it linux-based? Probably not. It's returning part of your User-Agent message, or some other message that identifies the host OS type of the originating message. All it tells us is that your computer is i686-pc-linux-gnu, but tells us nothing of the router. At 1MB FLASH, my money's on VxDoesntWorks.

The WRT54GC is based on the Sercomm IP806SM reference design, which is same platform as the Airlink101 AR315W, Alloy WRT2454AP, and Hawking HWR54G (Rev. M).

The unit comes with an internal antenna. It's possible to add an external antenna via the R-SMA plug. There seems to be a mechanical switch that gets (de-)activated when you open the tap of the external antenna port.

• Power: Input 3.3V DC 2.0A
• External antenna connector: SMA

Chips (from the FCC Internal photos)

• Marvel 88E6060 Fast Ethernet switch Manufacturer Product Page
• Etrontech EM636165TS 2MB chips (two on board) Manufacturer Product Page (PDF)
• Macronix LV29800BTTC-70 FLASH Low Voltage 8MB Rev B Top Boot TSOP Commercial 70ns Manufacturer Product Page (PDF)

FCC Internal photo (PDF)

FCC Information

FCCID Q87-WRT54GC