Debricking WRT54G... Help!!!

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alison.reid
DD-WRT Novice


Joined: 06 Sep 2011
Posts: 4

PostPosted: Sun Apr 08, 2012 9:19    Post subject: Debricking WRT54G... Help!!! Reply with quote
OS: Windows XP SP3 (fresh install, no a/v, no firewall)

Problem: I am trying to recover my router WRT54G v4 which I bricked when I accidentally uploaded a 2.6 kernel firmware. I have soldered a header on JP2 and borrowed a JTAG cable from a friend who previously used it to recover his WRT54G v2. However, I can't seem to get it to work with my v4. Here's the error message I get when I send a probe:

Code:
Probing bus ... Done

Instruction Length set to 5

CPU Chip ID: 11111111111111111111111111111111 (FFFFFFFF)
*** Unknown or NO CPU Chip ID Detected ***

*** Possible Causes:
1) WRT54G/GS is not Connected.
2) WRT54G/GS is not Powered On.
3) Improper JTAG Cable.
4) Unrecognized CPU Chip ID.


Odd Symptoms:
Whats really odd is that in the beginning only the router's power LED was flashing uncontrollably. It has been this way since it was bricked.

Now when I connect the JTAG cable, only an amber or orange light glows along with a white light. However, when I disconnect the JTAG cable and power up the router, power LED starts flashing as usual.

Troubleshooting:
1. HairyDairyMaid installs and starts successfully.

2. Checked LPT port is working fine with no conflicts and uses any interrupt assigned.

3. Checked soldering connections and everything seems alright.

The problem is I still can't connect to the router via LPT. I've read the wiki and searched the forums but I don't know how to handle this situation. Can someone kindly offer some advice?
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Murrkf
DD-WRT Guru


Joined: 22 Sep 2008
Posts: 12676

PostPosted: Sun Apr 08, 2012 12:33    Post subject: Reply with quote
Read the jtag article in the wiki, and check your soldering with a multimeter.

Serial recovery might be a better choice than jtag.

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barryware
DD-WRT Guru


Joined: 26 Jan 2008
Posts: 13049
Location: Behind The Reset Button

PostPosted: Sun Apr 08, 2012 15:02    Post subject: Reply with quote
make sure you do not have you cable connected backwards. That used to be a common problem.

Meaning: you do not have pin 1 of the jtag cable connected to pin 12 of the routers pcb (header plugged in backwards)

also.. power up the router, count to 1, launch the jtag utility.

EDIT: I can't find a pic of a v4's pcb. Make sure you are using the 12 pin jtag connector and not the 10 pin serial (x2) connector on the pcb

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alison.reid
DD-WRT Novice


Joined: 06 Sep 2011
Posts: 4

PostPosted: Mon Apr 09, 2012 0:42    Post subject: Reply with quote
Murrkf wrote:
Read the jtag article in the wiki, and check your soldering with a multimeter.

Serial recovery might be a better choice than jtag.


I only have access to a JTAG cable so I'll have to make due.


barryware wrote:
make sure you do not have you cable connected backwards. That used to be a common problem.

Meaning: you do not have pin 1 of the jtag cable connected to pin 12 of the routers pcb (header plugged in backwards)

also.. power up the router, count to 1, launch the jtag utility.

EDIT: I can't find a pic of a v4's pcb. Make sure you are using the 12 pin jtag connector and not the 10 pin serial (x2) connector on the pcb


I forgot to mention that in my troubleshooting list. I attached the pointed "triangle" to pin 1. I assuming that is correct.

I also attached a pic of WRT54G v4 PCB and labelled it just to be sure.



WRT54Gv4.jpg
 Description:
WRT54G v4.0
 Filesize:  492.52 KB
 Viewed:  9432 Time(s)

WRT54Gv4.jpg


barryware
DD-WRT Guru


Joined: 26 Jan 2008
Posts: 13049
Location: Behind The Reset Button

PostPosted: Mon Apr 09, 2012 0:44    Post subject: Reply with quote
jp1 is jtag.. earlier you stated you connected to jp2.. that is serial.
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alison.reid
DD-WRT Novice


Joined: 06 Sep 2011
Posts: 4

PostPosted: Mon Apr 09, 2012 5:48    Post subject: Reply with quote
barryware wrote:
jp1 is jtag.. earlier you stated you connected to jp2.. that is serial.

That was it! Thank you so much for that!!

I backed up CFE, NVRAM, and KERNEL, each three times. Is there any other precaution I need to take before I start the recovery process?

While doing my research, I came across posts on DD-WRT which said that since an incompatible firmware flash brick my router, I would only need to erase NVRAM and perhaps the Kernel.

Is that really the case? So I can skip erase:wholeflash and CFE flash? Just erase NVRAM and KERNAL and then tftp stock firmware?

In case if I do have to flash the CFE:
1. Which CFE file should I use? My own that I backed up earlier? or download one from your website? There are two different CFE files for v4 routers posted on your website, cfe_WRT54Gv4.zip(106KB) and WRT54G_v4.0_CFE.zip (102KB). Which one should I use?

2. Would I have to change my MAC address after flashing a CFE from your website?
Eko
DD-WRT Developer/Maintainer


Joined: 07 Jun 2006
Posts: 5772

PostPosted: Mon Apr 09, 2012 8:08    Post subject: Reply with quote
Don't touch the cfe!!!!

Just erase kernel and nvram, reboot, and router will wait for tftp transfer of new firmware.
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