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Ever tried JTAG unbrick recovery?

OP AdamOutler

20th March 2011, 03:06 AM   |  #1  
I bricked my captivate last night. It is possible to recover a black-screen bricked Captivate with JTAG. I was reading about using JTAG and it seems that RIFF is the most supported option. Basically, you use JTAG as a special serial device where you can send data directly to the board. It's how they load it at the factory.

I want to come up with a way to unbrick a captivate, but I don't want to spend $150 on a RIFF. It seems like overkill for such a small job. You can make a JTAG connection with 4 resistors and a parallel cable. I don't have a parallel cable on my computer.

Here's a pinout.


You can make your own JTAG (see attached file )

While I don't have a parallel port, I do have an Arduino. It is possible to set it up as a JTAG with a small bit of code.


I keep getting this question.. where can I get the parts and how do I do this? Well, you will get the parts from this post and I don't have any good recommendations about an interface board.
Quote:

I'd have to say that this method is doable by anyone who knows how to use a solder and flux well.

You will need
Header: http://www.mouser.com/ProductDetail/...VM5XnLHw%3d%3d
Receptical:http://www.mouser.com/ProductDetail/...VyeT43Dg%3d%3d
Soldering iron
Solder
desoldering sucker (just in case)
Flux
Sponge
super glue
alcohol
sewing needle
tweezers

How to apply the header:
1. flux the pads on the board
2. clean the iron with a sponge
3. apply a bead of solder to the tip of your iron
4. drag the soldering iron lightly across the board until the solder beads up on top of the pads (DO NOT TOUCH THE IRON TO THE PADS, they can be lifted) to tin the pads
5. apply flux to the header
6. tin the header
7. set tinned header on top of tinned pads
8. clean the soldering iron
9. carefully depress the individual pins on the header with the hot, clean, soldering iron
10. use a magnifying glass to verify all connections are against the board.
11. using a needle, apply superglue to the corners of the header
12. wait 1 hour
13. Clean with alcohol


As I said before, I got the receptacle board from "k-ww" on forums.hackaday.com
The receptacle installs the same way. You will need 30awg wire for the receptacle board breakout. You can see how I did it above.

In this picture the closest side has been cleaned with alcohol. The far side has burned flux on it.


I'm wondering what files do you send to the JTAG port? I suppose I'll find out soon enough. I purchased a spare phone today and I've got a development Captivate on the way. I will be attempting to pull the JTAG flash out of the phone if there isn't one available on-line somewhere.
Attached Files
File Type: rar Making a JTag Cable.rar - [Click for QR Code] (1.03 MB, 14897 views)
Last edited by AdamOutler; 28th September 2012 at 02:50 PM.
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20th March 2011, 03:16 AM   |  #2  
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Hmm, I have never bricked my cappy (knock on wood, lol) and I have never messed with jtag. But I have read on this forum that you can make a simple jig with three one hundred ohm resistors that will boot the phone into download mode. Again, I haven't bricked my phone, so I am not sure if this would work with a black screen bricked phone, but it seems simple enough, and cheap enough, to test. Basically, you take three 100ohm resistots and wire them together. Then, you touch the leads to pin 4&5 of the micro usb connector. This is supposed to boot the phone into download mode. From there, you can hook your phone to your computer via usb and use odin or a similar tool to flash back to stock. Again, I am fairly new and have never tested this personally, so I don't know if it works at all, or if it will work with a black screen bricked phone. I hope this does help you out, though!

Sent from my Samsung Captivate using XDA App.
ROM: Cognition v4.1.1
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20th March 2011, 03:24 AM   |  #3  
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@ OP

Did you try using Jig?
Just curious...
20th March 2011, 03:38 AM   |  #4  
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What part of "black-screen bricked Captivate" didn't you read...

And yes, FYI, he has his own Jig.
5th April 2011, 02:27 AM   |  #5  
For reference, the contacts on this are about the size of the "I" on "In God We Trust" on a USA dime (10 cents).


I just used a microscope to obtain this picture today.
Last edited by AdamOutler; 5th April 2011 at 04:11 AM.
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5th April 2011, 05:00 AM   |  #6  
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If you agreed to not sell the service of it. Connexion has one and might help you out with it. He does unbricking from a hard state. Idk anything about arduinos but I do know that on their forums they have alot of sdk's. And those guys might help.
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5th April 2011, 05:44 AM   |  #7  
Right now I am focusing on the physical connection. JTAG is a well documented standard. These pins are stupidly small. I am trying to figure out something as far as some sort of non-solder connection. Like some sort of compression connector... that is the purpose of the measurements.
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5th April 2011, 06:19 AM   |  #8  
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does it need to be non soldered?

as for non solder i think a small piece of circuit board material with all the copper you dont want etched or milled away is the best way to manufacture it. you will either need to laser cut the mask and etch it or i can mill it and solder maybe magnet wire to it, or maybe a small ribbon cable if you know of a source for that.

just noticed your sig, are you a vet? would be happy to help out a fellow vet, pm me if you want me to take a shot at making a connector.
Last edited by Dani897; 5th April 2011 at 07:20 AM.
5th April 2011, 07:25 AM   |  #9  
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EDITED: serial/parallel brain fart! it reads correct now!

also dont forget they do have USB to PARALLEL port cables about 40$ at futureshop. ALSO its is cheaper and easier to just add a PARALLEL port to your pc. they run about 10$ at any computer supply shop, it goes in the backplate and connects to your motherboard.

Most mother boards that dont have PARALLEL on it will have a pinout to add it!
Last edited by TRusselo; 6th April 2011 at 06:54 PM.
5th April 2011, 07:36 AM   |  #10  
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Quote:
Originally Posted by Trusselo

also dont forget they do have USB to serial port cables about 40$ at futureshop. ALSO its is cheaper and easier to just add a serial port to your pc. they run about 10$ at any computer supply shop, it goes in the backplate and connects to your motherboard.

Most mother boards that dont have serial on it will have a pinout to add it!

i believe the op can figure out the computer end of it. the issue is getting 12 wires in an area that measures under 1/100th of a square inch. each conductor is about .008" that is the thickness of the thinnest string on a banjo!. that is if the banjo has light tension strings on it. a better reference is about the thickness of 1.5-3 human hairs (or sheets of paper) depending on what figure you are following, obviously the thickness of both hair and papper varies.

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