Hardware

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Linksys WRT54Gx

WRT54G/GL/GS versions

The first 4 digits in the serial number (look on the box or the underside of the router) represent the hardware revision:

CDF0 = WRT54G v1.0
CDF1 = WRT54G v1.0
CDF2 = WRT54G v1.1
CDF3 = WRT54G v1.1
CDF5 = WRT54G v2.0
CDF7 = WRT54G v2.2
CDF8 = WRT54G v3.0
CDF9 = WRT54G v3.1
CDFA = WRT54G v4.0
CDFB = WRT54G v5.0
CDFC = WRT54G v5.1
CDFD = WRT54G v6.0
CDFE = WRT45G v7.0

CL7A = WRT54GL v1.0
CL7B = WRT54GL v1.1

CGN0 = WRT54GS v1.0
CGN1 = WRT54GS v1.0
CGN2 = WRT54GS v1.1
CGN3 = WRT54GS v2.0
CGN4 = WRT54GS v2.1
CGN5 = WRT54GS v3.0
CGN6 = WRT54GS v4.0
CGN7 = WRT54GS v5.0
CGN8 = WRT54GS v5.1

CJK0 = WRTSL54GS v1.0

See more information on the LinksysInfo Autopsy page.

DD-WRT supports versions 1 to 4 of the WRT54G, WRT54GL and WRT54GS hardware. WRT54G v5 and WRT54GS v5 are (un)oficially supported in the newest v23 SP1 beta "micro" version, but you need a JTAG cable to flash them (for now). These new routers have limited ram (2/8) and run on VxWorks and not Linux. DD-WRT does not currently support the WRT-54GX, Linksys's MiMo version router. DD-WRT is also reported to work on the WAP54G, but your mileage may vary.

WARNING: v22 isnt compatible to v4 routers and GL. they are really different. only v23 runs onto it. You would otherwise have to 'un-brick' your router (Revival Guide method)

NOTE: Additionally the stock firmware from Linksys on the WRT54G v4 and WRT54GL won't accept a firmware image over 3MB in size (you will get the error: "Upgrade are failed!"(sic) if you try) so you will need to flash the mini version of DD-WRT onto the router BEFORE flashing the std or voip versions. (Remember to hold reset button for 30 sec after flashing mini version.)

The WRT54Gx Boot Process

NVRAM

NVRAM (non-volatile RAM) is the place where the permanent settings are stored. On the command line you can view the NVRAM's content with

nvram show

A variable is stored/changed by issuing

nvram set <variable_name>="<value>"
nvram commit

You'll need to reboot to get the (changed) NVRAM executed.

Overclocking

The standard clock speed of a WRT54G is 200 MHz. DD-WRT allows overclocking the device to up to 300 MHz in various steps. It is also possible to underclock the WRT54G to 192 MHz, for example for troubleshooting crashes which may be caused by overheating. Also, newer Linksys firmware overclocks some models of the WRT54GS to 216 MHz, to prevent instability issues inherent in the 2.x versions.

The WRT54Gv4 and WRT54Gv5 have a processor that has a slightly different set of valid clock frequencies. Its highest available frequency is 252mhz (sbclock of 125mhz). Note that even though the box will boot at frequencies higher than this, the CPU will actually be running at its last known good speed, or default speed of 200mhz.

As of DD-WRT v23 SP1, this is mis-reported in the web UI since it reads from the nvram variables instead of checking the actual clock frequency. If you have a v4 or greater and think you are running at anything above 250mhz just because the web UI reports such, you are NOT.

To check your clock frequency, execute 'cat /proc/cpuinfo'. This will show you what frequency your processor is actually running at.

Additionally, although DD-WRT sets the nvram clkfreq variable so that it includes the sbclock, the sbclock variable is ignored. In example, clkfreq=240,126 ends up only running at 240mhz and 120mhz, because 120mhz is the sbclock frequency that matches the ratio for a 240mhz clock frequency.

Hardware Modifications

Hardware Modifications (mods) are not necessarily DD-WRT specific or compatible.

Serial Port
Additional external SMA-R connector
Dual Serial Port
SD-Card
Temperature sensor for WRT54G 2.x and WRT54GS with DS1820