My Linksys WRT54gs

August 4, 2013

The one and only WRT54G that I have in my hands is a WRT54GS version 5. This is the undesirable VxWorks based unit with a 2M instead of a 4M flash chip. Being an "S" unit does give it 16M of ram rather than the 8M that a WRT54G version 5 would have. It announces itself as running the Linksys 1.52.8 firmware. My unit has a serial number beginning with "CGN7", confirming that it is a GS version 5.

Of course I was curious to see exactly what the electronics inside looked like. There are numerous videos and sets of instructions (with plenty of misinformation) about how to open up the case. The case is a clever design, and simply snaps together with no screws (so for this model anyway, ignore any instructions that recommend prying loose rubber feet and removing screws). What is necessary is to remove or cut the "you will void warranty" sticker, then to briskly yank the purple front part of the case from the grey part. I removed the antennas prior to doing this (they readily unscrew), but it was by no means necessary to do this.

Note that the "S" for speedboost is somewhat of a gimmick. What this is is some kind of Broadcomm specific data compression. No doubt this works, but only if you have Broadcomm chips at both ends of the link (which is certainly possible, but hardly a given). The real bonus, as mentioned already is additional RAM in the GS units. It is rather a misnomer to even call this "additional RAM", as most the WRT54 units that ran linux had 16M of ram, and some even had 32M.

A much bigger image (3443 x 3206)

A look at the circuit board tells the story. There unit really only has 4 major chips. The heart of it is the Broadcomm BCM5352EKPB, which is an SoC ("system on a chip"). There are two memory chips; The MIRA P2V28S40BTP (which I am betting is the 16M of ram), and the chip with the green sticker (originally version 1.50.1 of the firmware - so this must be the 2M flash chip). The other chip is hidden under the "can" (shield) near where the antenna connections originate, and this is likely to be the BCM2050 wirless radio.

Here is a brochure for the BCM5352EL chip, which is likely very similar to the "EK" chip in my unit.

The "heart" of the broadcomm chip is a 32 bit MIPS processor running at 200 Mhz. Note that it supports two serial ports as well as a JTAG interface.

There are two "buttons". One is the reset button on the back of the unit (whether this is a real processor reset or something else is unknown to me as yet). The other is the strange long button that sits behind the Cisco logo (and includes an LED!) This can be used to associate the unit with a wireless device during initial setup, something I hope never to do. I think they call this the "Secure Easy Setup" button.


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Tom's Computer Info / tom@mmto.org