A thought about dead GD87s... - GSM-Forum

TriMesh · 06-28-2003, 01:47

Has anyone investigated the possiblity of reflashing these phones over the JTAG interface? Of course, I don't know for sure that the phone even has one, but it's ARM7 based, and most chips based on the ARM cores do have JTAG.

I do have the service manual for a GD-92, and this phone (which also has an ARM CPU) _does_ have a JTAG port on it - it's even brought out to extra large test points for ease of access...

If someone has the GD87 service manual, would it be possible to send me a copy, or alternatively to check if the CPU has TDI/TDO/TCK/TMS/nBSCAN (or TRST) from the CPU wired to test points?

OK, JTAG flashing is painfully slow, but all we would need to do is to restore the first 64K of the image so that the rest of the code could be loaded using WinMoDo - which would probably only take 5 minutes or so.

And no, I haven't killed my phone

Hanukkah · 12-14-2003, 16:40

How about programming the flash externally using programmer m8... is that possible?

Hanukkah · 12-14-2003, 17:01

There's info and schematics on building the JTAG dongle here. Hope this could help.

http://www.lart.tudelft.nl/projects/jtag/

TriMesh · 12-14-2003, 20:16

I've got the JTAG cable and software, it's just finding the correct points on the phone.

Reflashing the ROM out of circuit should be OK - but only flash the first part of the ROM (say 64 or 128K) - you will also need to remote the first 4 bytes from the firmware .rel file if you're going to do this.

I've been told that this works, but I've never tried it myself.

Hanukkah · 12-15-2003, 02:56

I'll try to get my hands on GD88 service manuals. I'm just not sure if my friends at Panasonic could get me a copy. I'll let you know once I get my hands on one.

06-28-2003, 01:47	#1 (permalink)
TriMesh Freak Poster Join Date: Dec 2001 Location: Shenzhen, China Posts: 327 Member: 7911 Status: Offline Thanks Meter: 7	A thought about dead GD87s... Has anyone investigated the possiblity of reflashing these phones over the JTAG interface? Of course, I don't know for sure that the phone even has one, but it's ARM7 based, and most chips based on the ARM cores do have JTAG. I do have the service manual for a GD-92, and this phone (which also has an ARM CPU) _does_ have a JTAG port on it - it's even brought out to extra large test points for ease of access... If someone has the GD87 service manual, would it be possible to send me a copy, or alternatively to check if the CPU has TDI/TDO/TCK/TMS/nBSCAN (or TRST) from the CPU wired to test points? OK, JTAG flashing is painfully slow, but all we would need to do is to restore the first 64K of the image so that the rest of the code could be loaded using WinMoDo - which would probably only take 5 minutes or so. And no, I haven't killed my phone

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12-14-2003, 16:40	#2 (permalink)
Hanukkah No Life Poster Join Date: Jul 2001 Location: RP Age: 48 Posts: 890 Member: 5246 Status: Offline Thanks Meter: 9	How about programming the flash externally using programmer m8... is that possible?

12-14-2003, 17:01	#3 (permalink)
Hanukkah No Life Poster Join Date: Jul 2001 Location: RP Age: 48 Posts: 890 Member: 5246 Status: Offline Thanks Meter: 9	There's info and schematics on building the JTAG dongle here. Hope this could help. http://www.lart.tudelft.nl/projects/jtag/

12-14-2003, 20:16	#4 (permalink)
TriMesh Freak Poster Join Date: Dec 2001 Location: Shenzhen, China Posts: 327 Member: 7911 Status: Offline Thanks Meter: 7	I've got the JTAG cable and software, it's just finding the correct points on the phone. Reflashing the ROM out of circuit should be OK - but only flash the first part of the ROM (say 64 or 128K) - you will also need to remote the first 4 bytes from the firmware .rel file if you're going to do this. I've been told that this works, but I've never tried it myself.

12-15-2003, 02:56	#5 (permalink)
Hanukkah No Life Poster Join Date: Jul 2001 Location: RP Age: 48 Posts: 890 Member: 5246 Status: Offline Thanks Meter: 9	I'll try to get my hands on GD88 service manuals. I'm just not sure if my friends at Panasonic could get me a copy. I'll let you know once I get my hands on one.