JTAG, how to use it to recover data?
 

Hey,

I heard here in the forum are a lot of people with good knowledge, so I try my luck here. The RAM is broken and I want to get the data back.
A friend said I could use JTAG to directly read the Internal Storage Chip, but I'm totally new to this, so does anyone of you can help me, what exactly to do?

Thanks in advance.

Re: JTAG, how to use it to recover data?
 

maybe it is possible, but first question: how likely are you to even get a JTAG jig? or you already have it?

What is the real problem with the device? also which device is this? N7x0, N8x0, N900, N9(50)?

Re: JTAG, how to use it to recover data?
 

I mean the thing is, a recovery service would cost about 3000€ and when a jtag jig costs about 200€ it's okay if it at least works, else i could sell it or use it in future, it's not a onetime purchase.

It's not a nokia. It's a OnePlus One, but in the other forums especially xda and oneplus forum, I didn't get help, because nobody knew anything. Everything i heard about this forum here gives me hope, that here are really user who know what they say.

Re: JTAG, how to use it to recover data?
 

To get anything out of the device via JTAG you need 2 things;

1. A JTAG reader/programmer of course. This is the easy requirement.
   
2. Access to the JTAG pins of the device.
   This might mean you need to take it apart until you can get at the board in the correct place.
   Note that in many cases the access to JTAG port is via PCB pads that are normally connected via pogopins... so you might need to solder wires to them in your "home environment"
   
3. The configuration files for the device, as without those you cannot ever hope to decipher what the physical layout of the JTAG chain is.
   If you don't have the configuration, there is no use pursuing this thing whatsoever. And the manufacturer will never give it to you... :D

Re: JTAG, how to use it to recover data?
 

I will buy a JTAG reader/programmer as soon as i know, that i have a high chance for success and how to use it.

a friend said he has a logic analyzer which could be used to find out which pin is where, but not sure

Re: JTAG, how to use it to recover data?
 

Don't bother, unless you have the configuration you will not get anything useful out of your device.

Even more so if you do not know the location of pads... In theory you could try to probe the signals with a scope or logic box but in practice... It just doesn't work that way...

Re: JTAG, how to use it to recover data?
 

Okay thanks for the answer, then I will look around for another possiblity :)

Re: JTAG, how to use it to recover data?
 

"Cadets, the AK47 consist of four main parts. It's these three: stock and barrel."

Re: JTAG, how to use it to recover data?
 

Browse around on hackaday, a DIY tech project website and feature blog mostly for hardware hacks and projects.
I think you could probably hack something together with a $1/free shipping USB Digispark (ATmicro85)to control everything some soldered on leads with alligator clips to grip some sewing needles as well as some sort of jig to hold the needles against the correct pins. Get the Arduino IDE and you should have an easy and cheap time with the JTAG hardware the only real difficulty is jigging the pin connections.
https://github.com/sowbug/JTAGWhisperer

I use the Arduino IDE for all sorts of fast dirty Atmel controller based automation and communication hacks, the hardware and the available libs and ease of use cant be beat even if you are not a great programmer.

Re: JTAG, how to use it to recover data?
 

@biketool, neat idea, but...

Are you aware how exactly a JTAG chain works? Unless you have the netlist and chip configuration you just have no use of whatever HW you have, whether it be a professional factory JTAG test automation jig or selfmade arduino job!