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 Post subject: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: April 29th, 2019, 13:40 
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Dear community,

the Digitech JamMan stereo is a device that lets musicians record short loops and to play them back while continuing to play on top of the previously recorded loop. It is typically (but not only used) by guitar players to create the illusion of a "one man band" in a live context, but can also be used for practicing and drafting of song ideas.

A few days back when turning on my JamMan Stereo, I realized I was not able to load all except for the 2 most recently recorded loops from the internal memory anymore. All other previously recorded loop locations are listed as "empty" loops without any stored data. Losing these loops would be prticularly painful since all of them were song ideas and unfortunately I have no backups.

I did not record or save any additional material since this incident to prevent overwriting of the data, so I assume the raw data of the must still be recoverable from the device. In fact, after installing complementary software for the device the first time, it indicates 70 MB of used space out of the 434 MB total space. Since most of the loops were relatively short (10 - 15 seconds) 70 MB seems an appropriate size of the raw wav data making up the "lost" data, so I hope that indeed it is still there.

Problem is that it is not possible to open the device as a regular USB device within Windows. also in the disk management tool it is not shown as mountable drive. It does, however, show up in the device manager as a COM & LPT device even though it is connected via USB.

Long story short: Any of you have an idea how to do a recovery of the data? I know there is some serious tech-knowledge on here, so I hope also people not familiar with this particular device might share some insight. Last resort would be to open the device, rip out the storage and find a way to connect it to a computer. Thing is that it is probably not going to be cheap to have some expert do that (personally I cant) and most probably the device will be scrap after.

Any other possibilities?

Attached a few screenshots from my PC / the JamMan software:

https://ibb.co/YZh97py JamMan Stereo SW
https://ibb.co/MMZ7Rk5 Device Manager
https://ibb.co/9TWXt2z Disk Manager (Partition in Chinese characters is system reserved, NOT the JamMan)


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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: April 29th, 2019, 23:56 
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Joined: February 2nd, 2019, 1:21
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What is the TOSHIBA transmemory usb device in device manager. is this related to this jamman.


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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: April 30th, 2019, 8:01 
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Joined: April 29th, 2019, 13:39
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Hi Dananjaya,

thanks for the feedback.

The Toshiba transmemory usb device is/was just a regular consumer USB thumb-drive that was attached when I took that screenshot.

Not related to the device in question, unfortunately.


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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: April 30th, 2019, 20:11 
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I wonder if the COM device provides access via Telnet?

Could we see photos of the PCB(s)?

Is there a firmware upgrade that we can dissect?

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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: April 30th, 2019, 20:34 
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Are you able to format an SD card and record a short loop on it? If you then dump the first few megabytes of the card, we should then have some idea of the file system, file format, and possibly the OS (Linux?), assuming that the card is formatted in the same way as internal memory.

I'm also assuming that this procedure will not touch the contents of internal memory.

ftp://ftp.digitech.com/pub/PDFs/Manuals/JamMan_Stereo/JamMan_Stereo_manual_18-0707-B.pdf

Edit: Do you have any saved loops that we could examine?

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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 1st, 2019, 11:11 
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Joined: April 29th, 2019, 13:39
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Quote:
I wonder if the COM device provides access via Telnet?


Would love to try if you explain a bit how. The device is connected via USB but showing up as a COM device in the device manager

Quote:
Could we see photos of the PCB(s)?


Attached:
https://ibb.co/HzRyKQq
https://ibb.co/FJ7dws4
https://ibb.co/ZgqhNF7

Quote:
Is there a firmware upgrade that we can dissect?


Firmware update is only possible via the "JamManager XT" software. When I connect to the device using that software it says "no update availible"

Quote:
Are you able to format an SD card and record a short loop on it? If you then dump the first few megabytes of the card, we should then have some idea of the file system, file format, and possibly the OS (Linux?), assuming that the card is formatted in the same way as internal memory.

I'm also assuming that this procedure will not touch the contents of internal memory.

ftp://ftp.digitech.com/pub/PDFs/Manuals ... 0707-B.pdf


Quote:
Edit: Do you have any saved loops that we could examine?


Attached:
https://www.file-upload.net/download-13 ... 2.wav.html


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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 1st, 2019, 18:07 
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Wanted to edit the above post, but couldnt find the edit button :o :?:

Anyway, thanks for the support and the questions you raised.

For the SD card recording I will try in the next days. Have to get my hands on an SD card before I can try that.


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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 1st, 2019, 19:39 
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ISTM that a plausible approach would be to use the embedded (?) "SAM-BA Monitor" to dump the NAND flash addresses via the USB or Debug port (see section 10.5 of the SAM9G45 datasheet).

The software appears to be included in the AT91SAM9G45-EKES evaluation kit.

AFAICT, one way to invoke the SAM-BA monitor is to invalidate the NAND flash IC during the POST. A safe way to do this would be to short the NAND's R/B* pin to ground during this time.

WARNING: The monitor commands are Case Sensitive and therefore potentially destructive. For example, uppercase "W" is a Write Word command whereas lowercase "w" is Read Word. Crazy !!!


References:

JamMan Stereo Looper, Digitech (PCB images):
https://i.ibb.co/3Fg0kjQ/IMG-20190501-222940.jpg
https://i.ibb.co/HYg9zNT/IMG-20190501-223230.jpg
https://i.ibb.co/d2XvfyD/IMG-20190501-223259.jpg

JamMan Stereo User Manual:
ftp://ftp.digitech.com/pub/PDFs/Manuals ... 0707-B.pdf

AT91SAM9G45-EKES User Guide, Atmel, ARM SoC, marking ATSAM9G45-CU, TFBGA-324:
http://ww1.microchip.com/downloads/en/D ... oc6481.pdf

SAM9G45, Atmel, SMART ARM-based Embedded MPU, 400MHz ARM926EJ-S ARM Thumb processor, 64KB SRAM, 64KB ROM:
http://ww1.microchip.com/downloads/en/D ... asheet.pdf

MT29F4G16ABBDAHC:D, Micron, FLASH - NAND Memory IC 4Gb (256M x 16) Parallel, marking NW163, 63-VFBGA:
https://4donline.ihs.com/images/VipMast ... 9293-1.pdf
https://www.micron.com/support/tools-an ... fbga=nw163
https://www.digikey.com/product-detail/ ... ND/2380271

NT5TU64M8DE-3C, Nanya, 512Mbit DDR2 SDRAM, 1.8V:
http://static6.arrow.com/aropdfconversi ... nsumer.pdf

CS42528-CQZ, Cirrus Logic, 114 dB, 192 kHz 8-Ch Codec with S/PDIF Receiver, QFP-64:
http://www.mouser.com/ds/2/76/cs42528_f1-293694.pdf
https://d3uzseaevmutz1.cloudfront.net/p ... 28eb-2.pdf

BA4580R, Rohm, Dual Audio Operational Amplifier, +/-2V - +/-16V, marking 4580R, SOP-8
http://rohmfs.rohm.com/en/products/data ... 80rf-e.pdf

NJM2122, JRC, ultra low noise dual operational amplifier, +/-2V - +/-7V, marking 2122, DMP8:
https://www.njr.com/semicon/PDF/NJM2122_E.pdf

PZT651, ON Semi, NPN transistor, 60V, 2A, marking 651, SOT-223
https://www.onsemi.com/pub/Collateral/PZT651T1-D.PDF

PZT751, ON Semi, PNP transistor, -60V, -2A, marking ZT751, SOT-223:
https://www.onsemi.com/pub/Collateral/PZT751T1-D.PDF


Attachments:
SAM-BA_command_list.GIF
SAM-BA_command_list.GIF [ 40.75 KiB | Viewed 2166 times ]
AT91SAM9G45_SoC_board_arch.jpg
AT91SAM9G45_SoC_board_arch.jpg [ 86.79 KiB | Viewed 2166 times ]

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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 1st, 2019, 23:20 
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The SAM-BA tools appear to be available here:
https://www.microchip.com/DevelopmentTools/ProductDetails/Atmel%20SAM-BA%20In-system%20Programmer

Perhaps you could try this forum for better advice:
http://www.at91.com/index.php

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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 3rd, 2019, 7:38 
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Whow, that's a lot of information about the HW on the PCB and helps me to get some idea how to help whrnzn :thumbsup:

whrnzn asked me whether I'm able to help him on his issue and that's why I read this thread. I'm a SW engineer familiar with Unix/Linux and have very limited HW background.

As far as I understand the DDR RAM is used by JamMan to persist all the loops in some filesystem and we just have to dump the 512MB DDR RAM somehow on the SD/SDHC memory card. The optional external SD/SDHC card then can be removed from JamMan and then some intelligent data recovery SW can be used on the filesystem.

Given the fact this is an ARM based SOC I assume there is a Linux running in the box or any other similar OS. If it's possible to get access via a console as root a dd command or equivalent can be used to dump the data from DDR RAM to SD/SDHC card. So we have to find some way to get access to an OS console.

I don't think this can be done via the SAM-BA which allows to modify any contents in the NAND flash and to patch and inspect any memory location. I have no idea how it's possible to get access to the DDR and SD/SDHC via SAM-BA. May be I'm wrong - but right now I have no idea how to get this done.

Other ways to access the box may be to use the USART or ethernet port (telnet ?) if they are accessible and served by the running OS. I have no idea how to test whether this will work and how to connect.

There exists a Windows Application which allows to access the internal memory via USB and on section 10.5.3 they write
Code:
10.5.3 USB Device Port
10.5.3.1 Supported External Crystal / External Clocks
The only frequency supported by SAM-BA Monitor to allow USB communication is a 12 MHz crystal or external
clock.
10.5.3.2 USB class
The device uses the USB communication device class (CDC) drivers to take advantage of the installed PC RS-232
software to talk over the USB. The CDC class is implemented in all releases of Windows ® , beginning with
Windows 98SE ® . The CDC document, available at www.usb.org, describes how to implement devices such as
ISDN modems and virtual COM ports.
The Vendor ID is Atmel’s vendor ID 0x03EB. The product ID is 0x6124. These references are used by the host
operating system to mount the correct driver. On Windows systems, the INF files contain the correspondence
between vendor ID and product ID.


There is a CDC driver available for Linux (see https://www.ccsinfo.com/faq.php?page=linux_cdc for example). Not sure whether this driver can be used to get access to the DDR. They most probably use a proprietary protocol to access and control JamMan and in order to use this interface the protocol has to be reverse engineered.

I just wrote down my thoughts on the issue to give you an idea which alternatives I see. Please correct me if I'm wrong.

Do you think the SAM-BA can be used to get some kind of console? What about the UART? eth would be great but I frankly doubt the drive this from the os because the SamMan uses the USB serial connection for external communication. It also would be very helpful to know which OS is running in the box.


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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 3rd, 2019, 18:52 
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AISI, this is the block diagram corresponding to the JamMan Stereo:

Code:
    2x 512Mbit           AT91SAM9G45 SoC

  2x NT5TU64M8DE-3C  .--------------------------.
      .-----.        |.-----------.             |  .-----------.
      |SDRAM|--------|| 64KB RAM  |             |--|I/O devices|
      '-----'        |'-----------'             |  '-----------'
  .-----------.      |.-----------.             |     .----.
  |JamMan code|      || 64KB ROM  |             |-----|SDHC|
  |-----------|      ||           | .----------.|     '----'
  |           |------||SAM-BA code| |USB-RS232C||
  | Loop data |      |'-----------' '----------'|
  |           |      '-------------------|------'
  |       R/B*|---------.                |
  '-----------'         |                |
                        |                | SAM-BA traffic
4Gbit NAND flash       ===               |
                       GND               |
MT29F4G16ABBDAHC:D                   .--------.  CDC driver
                     temporarily     |USB host|  VID 0x03EB
                     ground R/B*     '--------'  PID 0x6124
                     pin during          |
                     POST to        .-----------.
                     invoke SAM-BA  |  Windows  |
                     monitor        |SAM-BA tool|
                                    '-----------'

The Soc has a mask ROM which enables it to POST and set up the USB port. It also contains the code for the SAM-BA monitor. At the time of manufacture, the NAND flash is vacant

During the post, the SoC looks for boot devices. If it doesn't find any, it invokes its SAM-BA monitor and waits for commands from the USB-serial device. The designer then uploads his application code (eg JamMan) into block #0 of the NAND flash memory using an appropriate SAM-BA tool. He could alternatively use the SAM-BA commands directly, but the tool makes this a lot easier and safer. Block #0 is guaranteed to be good by the NAND manufacturer. The remainder of the NAND is used to stored the guitar loops.

AISI, you need to temporarily ground the NAND's Ready/Busy* pin during the POST in order to invalidate it. The SoC is then unable to find a boot device, which then causes it to invoke its SAM-BA monitor. AFAICT, you should be able to confirm that SAM-BA is active by typing "V" (Display Version) via a terminal program such as PuTTY or HyperTerminal.

If you get this far, then you should be able to read and write to NAND flash. You may need to configure the address spaces first, though.

As for the OS, ISTM that this is transparent and therefore irrelevant.

I should add that R/B* should only be grounded until the monitor is active. It should then be released from ground.

Once again, I think that the AT91 forum is a much better place for support. I would at least ask for confirmation from one of their engineers before proceeding with my suggestions.

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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 4th, 2019, 4:11 
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Thank you very much for the block diagram. This helped me to get a much better understanding of the SOC and it's external storage/memory devices. As you saw i thought the loops will be stored in DDR2 which is absolutly wrong because this is no persistent storage :?

I didn't know the loops are stored in the NAND. So the task will be to read the 4Gb/512MB from the NAND, find out at which memory location the loops are stored (skipping the JamMan code starting at #0) and then find out the format the loops are stored in NAND. I hope a common file system is used and i don't have to reverse engineer a proprietary file format.

Given this I now understand why you just tell me to use SAM-BA and just ignore the OS. For me it sounded to be the easiest way to retrieve the loops but I'm now with you to use SAM-BA.

fzabkar wrote:
Block #0 is guaranteed to be good by the NAND manufacturer. The remainder of the NAND is used to stored the guitar loops.

Do I get you right telling me the loops will start at #1? I think there will be some SamMan firmware code reside somewhere in the NAND, hopefully continuous starting from #0 and I have to find the starting address of the loops in the NAND.
fzabkar wrote:
AISI, you need to temporarily ground the NAND's Ready/Busy* pin during the POST in order to invalidate it. The SoC is then unable to find a boot device, which then causes it to invoke its SAM-BA monitor. AFAICT, you should be able to confirm that SAM-BA is active by typing "V" (Display Version) via a terminal program such as PuTTY or HyperTerminal.

I don't have physical access to SamMan as of now so I cannot check where this pin is located and where I can connect it to ground. Will work on this as soon as I have physical access.
fzabkar wrote:
You may need to configure the address spaces first, though.

I know what an address space is. But what do I have to do for this? Set a base address for the memory where the loop data starts?
fzabkar wrote:
Once again, I think that the AT91 forum is a much better place for support. I would at least ask for confirmation from one of their engineers before proceeding with my suggestions.

Got it and will do. But before starting to bother the guys in the other forum I'd like to get at least a basic understanding what has to be done and how to do it. Your give me valuable assistance on this :good:


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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 4th, 2019, 10:52 
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fzabkar wrote:
AISI, this is the block diagram corresponding to the JamMan Stereo:

Code:
    2x 512Mbit           AT91SAM9G45 SoC

  2x NT5TU64M8DE-3C  .--------------------------.
      .-----.        |.-----------.             |  .-----------.
      |SDRAM|--------|| 64KB RAM  |             |--|I/O devices|
      '-----'        |'-----------'             |  '-----------'
  .-----------.      |.-----------.             |     .----.
  |JamMan code|      || 64KB ROM  |             |-----|SDHC|
  |-----------|      ||           | .----------.|     '----'
  |           |------||SAM-BA code| |USB-RS232C||
  | Loop data |      |'-----------' '----------'|
  |           |      '-------------------|------'
  |       R/B*|---------.                |
  '-----------'         |                |
                        |                | SAM-BA traffic
4Gbit NAND flash       ===               |
                       GND               |
MT29F4G16ABBDAHC:D                   .--------.  CDC driver
                     temporarily     |USB host|  VID 0x03EB
                     ground R/B*     '--------'  PID 0x6124
                     pin during          |
                     POST to        .-----------.
                     invoke SAM-BA  |  Windows  |
                     monitor        |SAM-BA tool|
                                    '-----------'



Dear fzabkar,

thanks a lot for the incredible support and helpful input here, also regarding other potential sources of expertise (e.g. http://www.at91.com).
As mentioned by framp, he will support me with the technical execution of the recovery attempt. Unfortunately I can only provide him with the physical device earliest in July.

As for your idea to try recording some loops on an SD card for analysis of the file system, I would like to make sure there is an existing data dump before doing that. Just to have a fall-back option in case the internal storage is actually used (and potentially overwritten) in the process.

For the sake of amusement, attached the first reply from the official manufacturer support. The original message that I sent to them was a slighly adapted version of the opening post of this topic. Even tough I assume chances of receiving a useful feedback are slim, I will not let them get away with this so easily and persist to get some technical support on how to recover the files that are apparently still on the device (70mb of 434mb internal storage occupied).

Quote:
Hey [name],
Are you sure that you're not accidentally in the external memory location of the pedal?

You may have accidentally deleted all the internal memory contents at some point before the last 2 loops were created. If that's the case, then it cannot be undone.
[name] [surname]
Technical Support Engineer
Harman Professional Solutions


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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 5th, 2019, 2:50 
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The following thread has a "SAM-BA CDC 2.12 on Linux" screenshot for the AT91SAM9G45 SoC:
http://www.at91.com/viewtopic.php?t=22044

Unfortunately the user was unsuccessful in dumping his NAND flash. :-(

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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 5th, 2019, 7:37 
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I managed to get sam-ba 2.18 up and running on my Linux Laptop :) . According the samba-ba doc for linux it uses USB CDC class for communicating to the host so I now need to

1) get physical access to the looper
2) exactly know how to get the loop device boot the sam-ba monitor instead of the JamMan FW. @fzabkar: You explained very detailed how this should be possible. Frankly I still don't understand exactly how to get this done. I will ask in the at91 forum for help on this.
3) crossing fingers the looper starts in sma-ba monitor mode
4) crossing fingers sam-ba 2.18 detects the looper and opens the GUI
5) crossing fingers I will not see the issues reported in this post

The Linux doc is a bit outdated and doesn't mention the 64bit executable which is available now. Interesting to see they use TCL. I never did any programming in TCL. Let's see whether I have to start learning TCL :mrgreen:


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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 5th, 2019, 16:42 
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AIUI, the NAND flash is accessed by loading an applet into RAM via the SAM-BA monitor, and then transferring control to this applet. I don't know whether this is done transparently by the tool, or whether it needs to be done via a script, or some other way. (At this point it is a case of the blind leading the blind.)

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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 6th, 2019, 9:26 
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fzabkar wrote:
... (At this point it is a case of the blind leading the blind.) ...

Don't hide your light under a bushel :D . You helped me extremely good to get on speed on this issue and I now have a good feeling I will be able to dump the data. The only open question I have is how I can safely connect the two pins R/B* (pin 7) and Vss (pin 13,25,37 and 48) on the NAND without touching other pins by error. I'm a SW engineer and have no experience on this. Maybe you can advice on this?

As you suggested I created a thread in the at91 forum to confirm your instructions how to boot in sam monitor mode instead of the FW are correct (They are already confirmed :) )


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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 6th, 2019, 18:44 
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I would trace the R/B* pin to a less "busy" area of the PCB, assuming this is available. Alternatively, there may be a hot-key to invoke the monitor, but that would be a question for the Atmel forum.

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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: May 6th, 2019, 19:21 
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The reason I chose the R/B* pin was that it is designed to be shorted to ground. Therefore there is no risk of damage. That's the nature of "open drain" signals. OTOH, shorting the CS pin to ground is potentially unsafe, IMHO.

I'm assuming that the SoC times out while waiting for the NAND to assert the Ready signal. Hopefully it doesn't hang forever while the NAND is Busy, otherwise you may need a different approach.

In any case it appears that the knowledgeable people at at91.com are now on board. Good luck.

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 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: August 8th, 2019, 6:36 
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Location: Next to Stuttgart, Germany
Just an update for everybody facing a similar issue: I managed to login into the looper via UART. The looper is runnign QNX, a posix compliant Unix. I was able to dump the NAND data and a tool called etfsctl. For details visit [url=http://www.at91.com/viewtopic.php?f=9&t=29088}this thread [/url].

Now I have to recover the RIFF WAVE files from the dump. My first try was to scan for the WAVE header RIFF<file size-8(uint32)>WAVE and extract the found wave files. When I play them I can hear some sound with partially strange noise. It sounds to me the WAVE files have to be processed somehow before playing them.

The loop file structure is as follows:
Code:
.
├──Patch61
│  ├── patch.xml
│  └── PhraseA
│      ├── phrase.wav
│      └── phrase.xml
└──Patch62
   ├── patch.xml
   └── PhraseA
       ├── phrase.wav
       └── phrase.xml

patch.xml for Patch61
Code:
<?xml version="1.0" encoding="UTF-8"?>
<JamManPatch device="JamManStereo" version="1" xmlns="http://schemas.digitech.com/JamMan/Patch">
<PatchName>Loop_61</PatchName>
<RhythmType>StudioKickAndHighHat</RhythmType>
<StopMode>StopInstantly</StopMode>
<SettingsVersion>0</SettingsVersion>
<ID>2e3060ae-1dd5-11b2-b40b-07403f8812ba</ID>
<OriginID>9324d1d0-1dd4-11b2-b40b-7fdc08c7c090</OriginID>
<Metadata>
<Description></Description>
<Artist></Artist>
<Genre>unspecified</Genre>
<Rating>0</Rating>
<Tags></Tags>
</Metadata>
</JamManPatch>

and phase.xml for Phase61 in
Code:
<?xml version="1.0" encoding="UTF-8"?>
<JamManPhrase xmlns="http://schemas.digitech.com/JamMan/Phrase" version="1">
<BeatsPerMinute>106.883</BeatsPerMinute>
<BeatsPerMeasure>4</BeatsPerMeasure>
<IsLoop>1</IsLoop>
<IsReversed>0</IsReversed>
<SettingsVersion>0</SettingsVersion>
<AudioVersion>0</AudioVersion>
<ID>2e3060ae-1dd5-11b2-b40b-07403f8812ba</ID>
</JamManPhrase>

Looks like BeatsPerMinute and BeatsPerMeasure is used somehow to modify the raw WAVE data. As far as I understand theses values are used by the looper to be able to playback the loops in different speed.

Looks like I have to dig into the WAVE format details and how the WAVE date is modified by loopers :?


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