Seagate Serial terminal on HDD.15

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Enoch
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Seagate Serial terminal on HDD.15

Postby Enoch » Sat Dec 07, 2013 9:29 am

Hi,

I've noticed that the latest generation of Seagate drives (HDD.15) like the ST4000DM000 series, they no longer have the full diagnostic handler present, only very few commands actually respond anymore.

Does anyone know if there is now some kind of unlock sequence required to provide full access, or is it now closed?

Whilst I'm at it, does anyone know if the professional data recovery tools (like PC3k) actually have support yet to read/write the service area on these drives?

Thanks,

Enoch.

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Re: Seagate Serial terminal on HDD.15

Postby Spildit » Sat Dec 07, 2013 4:18 pm

I didn't test / play with any of those drives yet.
At any rate can you go to level C and issue the Q command, and post here the output ?

/C
Q

This will (hopefully) display the list of commands accepted by the drive. Thanks.
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Re: Seagate Serial terminal on HDD.15

Postby fzabkar » Sat Dec 07, 2013 5:22 pm

Enoch wrote:I've noticed that the latest generation of Seagate drives (HDD.15) like the ST4000DM000 series, they no longer have the full diagnostic handler present, only very few commands actually respond anymore.

Can you show us what you've noticed? ;-)

Can you also tell us which hardware you are using to access the terminal port? AIUI, the new drives have 1.8V interfaces whereas the typical TTL adapters use 3.3V I/O.

If you are using a USB-RS232 bridge, can you tell us the part number of the bridge IC? How does it show up in USBDeview or UVCView?

What baud rate and port settings do the HDD.15 drives use?

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Re: Seagate Serial terminal on HDD.15

Postby Enoch » Sun Dec 08, 2013 1:32 am

As I stated in the other thread:

Most of the diagnostic terminal commands have been disabled in the HDD.15 series. It only responds to a select few of the commands, it appears that all others have been culled from the handler, or are blocked until some kind of unlock is issued.

It definitely appears that Seagate have tried to disable external parties from accessing their diagnostic code, maybe to hinder external recovery companies, or maybe to hide their Advanced Format IP from prying eyes.

I have the proper skills and tools to know what I am talking about, so please, forget the newbie suggestions. The UART rate and adaption is the same as from the most previous gen drives, that hasn't changed (ie: It's still 38k4, 8N1 and the three standard mode switches are in place, ONLINE, DIAG and ESLIP).

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Re: Seagate Serial terminal on HDD.15

Postby Spildit » Sun Dec 08, 2013 1:36 am

Maybe you need additional code to perform additional actions ?
Like with Self-Scan code that was removed from F3 arch drives, I bet Seagate still use it at factory but doesn't ship the drives with it anymore. Maybe it's the case that Seagate have additional code that they erase from the drives prior to shipping.
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Re: Seagate Serial terminal on HDD.15

Postby Enoch » Sun Dec 08, 2013 1:38 am

fzabkar wrote:
Enoch wrote:I've noticed that the latest generation of Seagate drives (HDD.15) like the ST4000DM000 series, they no longer have the full diagnostic handler present, only very few commands actually respond anymore.

Can you show us what you've noticed? ;-)

Can you also tell us which hardware you are using to access the terminal port? AIUI, the new drives have 1.8V interfaces whereas the typical TTL adapters use 3.3V I/O.

If you are using a USB-RS232 bridge, can you tell us the part number of the bridge IC? How does it show up in USBDeview or UVCView?

What baud rate and port settings do the HDD.15 drives use?



Hi fzabkar:

The only commands that the drive responds to are: Ctrl-Z (DIAG), Ctrl-R (ONLINE), Ctrl-T (ESLIP) and Ctrl-A (when in DIAG mode) to show a brief "Info" on the HW.

When in DIAG mode, you can do level traversal (/x) and the drive will switch, but any attempt to issue any commands will result in a null response, or an "Invalid command".

Enoch.

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Re: Seagate Serial terminal on HDD.15

Postby fzabkar » Sun Dec 08, 2013 3:31 am

Thanks for the clarification. However, I'd still like to know which bridge chip your TTL adapter is using. This would help those people who are struggling with other drives that have 1.8V I/O levels. The high trigger level for a 3.3V chip is about 2.3V (= 0.7 x 3.3), so this would suggest that such chips would be unsuitable for 1.8V I/O. That's what made me curious about your setup.

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Re: Seagate Serial terminal on HDD.15

Postby Enoch » Sun Dec 08, 2013 5:36 am

fzabkar wrote:Thanks for the clarification. However, I'd still like to know which bridge chip your TTL adapter is using. This would help those people who are struggling with other drives that have 1.8V I/O levels. The high trigger level for a 3.3V chip is about 2.3V (= 0.7 x 3.3), so this would suggest that such chips would be unsuitable for 1.8V I/O. That's what made me curious about your setup.


I'm not using a bridge chip, I'm actually using one of my own custom tools that uses an FPGA to do high-speed, flexible voltage level translation. Regardless, Vcc on HDD.15 is 1v8, but the external serial is at the usual 3v3 for external serial comms on most chipsets.

Enoch.

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Re: Seagate Serial terminal on HDD.15

Postby Moltke » Sun Dec 08, 2013 7:01 pm

Enoch wrote:
The only commands that the drive responds to are: Ctrl-Z (DIAG), Ctrl-R (ONLINE), Ctrl-T (ESLIP) and Ctrl-A (when in DIAG mode) to show a brief "Info" on the HW.

When in DIAG mode, you can do level traversal (/x) and the drive will switch, but any attempt to issue any commands will result in a null response, or an "Invalid command".

Enoch.

it is possible that full- job with the RS232-port is disabled through stuff

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Re: Seagate Serial terminal on HDD.15

Postby Spildit » Sun Dec 08, 2013 7:41 pm

Moltke wrote:it is possible that full- job with the RS232-port is disabled through stuff


Do you know of a way to "activate" or "enable" it by terminal or ATA ?
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Re: Seagate Serial terminal on HDD.15

Postby Moltke » Sun Dec 08, 2013 8:29 pm

Spildit wrote:Do you know of a way to "activate" or "enable" it by terminal or ATA ?

ST4000DM000 I did not have. have not tried

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Re: Seagate Serial terminal on HDD.15

Postby Spildit » Sun Dec 08, 2013 8:41 pm

Moltke wrote:
Spildit wrote:Do you know of a way to "activate" or "enable" it by terminal or ATA ?

ST4000DM000 I did not have. have not tried


Ok, same as me.
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Re: Seagate Serial terminal on HDD.15

Postby fzabkar » Sun Dec 08, 2013 8:47 pm

Enoch wrote:
fzabkar wrote:Regardless, Vcc on HDD.15 is 1v8, but the external serial is at the usual 3v3 for external serial comms on most chipsets.

A Seagate user actually measured 1.8V at the jumper pins ...

BTW, how do you achieve +3.3V I/O on a PCB that doesn't have a +3.3V supply?

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Re: Seagate Serial terminal on HDD.15

Postby fzabkar » Mon Dec 09, 2013 4:46 am

Please break out your multimeter and measure the voltages on the jumper pins, with the TTL interface disconnected.

Then please identify the +3.3V regulator on the HDD PCB, if it exists.

If you need some help to do this, then read my tutorial on the subject:

Tutorial - Linear and Switchmode Regulators used in HDDs:
viewtopic.php?f=59&t=231

I think you'll agree that I'm not asking for much. In fact I'm asking for a lot less than you.

This first-time multimeter user had no trouble performing the same measurements:
http://forums.seagate.com/t5/Desktop-HD ... 761#M33350

BTW, I'm also an Aussie, and I'm electrical engineer with more than 30 years chip-level experience in electronics, so I'm not a noob.

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Re: Seagate Serial terminal on HDD.15

Postby Enoch » Mon Dec 09, 2013 5:13 am

I can see (and measure) 12v, 5v, 3v3 and 1v8 on that board, the voltages are stable and all available on the HDA connector.

Edit:

Just to confirm this, I also found and plugged in one of my FTDI 3v3 USB to UART cables and it works exactly the same as my flexible level translated interface.

Enoch.

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Re: Seagate Serial terminal on HDD.15

Postby fzabkar » Mon Dec 09, 2013 7:25 am

So the I/O voltage at the jumper pins is in fact +1.8V, not +3.3V, isn't it?

As for the HDA voltages, the preamps in earlier models required +5V and -5V supplies. If what you say is correct, then it appears that this latest model uses +3.3V for the preamp's write section. This is consistent with some older models, and also with current 2.5" drives. However, it's a surprising departure from previous 3.5" designs.

Preamp Block Diagrams:
viewtopic.php?f=59&t=229&p=582

As for +12V and +1.8V being available at the HDA connector, I confess that I'm surprised. I don't recall seeing this in any other drive to date. Could we see a detailed photo of both sides of the PCB? Could you hazard a guess as to why either the +12V supply or the Vio supply would be powering anything inside the HDA? This is becoming very intriguing. I hope that you could indulge my curiosity.

As for the term "TTL", it is in fact an appropriate term, although chip manufacturers refer to it more precisely as Low Voltage TTL (LVTTL or LVCMOS, depending on the implementation).

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Re: Seagate Serial terminal on HDD.15

Postby Enoch » Mon Dec 09, 2013 7:36 am

Franc:

If you mean he voltage on pin #4 of the external connector, that to my knowledge is a GPIO line, not a voltage line... so it makes sense it would be using the MCUs internal Vcc. I have been told (and it seems to be correct) that the two UART lines (pins 1 & 2) are set to 3v3. I don't know for sure what pin 4 does, but I believe it may be used to force something like SATA-1 (1.5G) compliance?

I haven't got my PCB scanner setup in my Sydney office yet, but I am sure that I can take a photo of each side of the PCB for you, no problems. I'll try to get it done and up here later on tonight after I get home.

Enoch.

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Re: Seagate Serial terminal on HDD.15

Postby fzabkar » Mon Dec 09, 2013 7:55 am

Yes, I do believe pin #4 is a GPIO pin. In earlier series (eg 7200.11) it was programmed as an input and was used for limiting the SATA link rate. This function was disabled in the 7200.12. In some firmware versions (eg Apple) pin #4 is programmed as an output pin and is used to provide 1-wire digital temperature data to Apple's hardware.

As for the Tx and Rx pins, they are not 3.3V LVTTL. Please measure them for yourself. It may be that 1.8V LVTTL is tolerated by your serial device, but that doesn't mean that other devices will do likewise.

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Re: Seagate Serial terminal on HDD.15

Postby Enoch » Mon Dec 09, 2013 8:01 am

Franc:

Ok, witness my awe-inspiring MS paint skillz... ;) My apologies in advance, I haven't got any real photo editing tools on this PC.

HDD_15_4TB_PCB_Front.jpg
The attachment HDD_15_4TB_PCB_Back.jpg is no longer available


Hopefully the .JPGs will be attached to this post.

Enoch.
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HDD_15_4TB_PCB_Back.jpg

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Re: Seagate Serial terminal on HDD.15

Postby xsoliman » Mon Dec 09, 2013 3:45 pm

Sorry I cant help or comment
Haven't even got my hands on a .14 yet, yet alone a .15

On some .12 and the .14 I believe you need to "short the read/write channel" to get ^Z terminal access, but your beyond that point


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