Understanding SSD compatibility issues, FITLET2ERR008

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snoopstah
Posts: 2
Joined: Sat Mar 07, 2020 7:10 am

Understanding SSD compatibility issues, FITLET2ERR008

Post by snoopstah »

Hi,

I've been looking at the latest erratum for the Fitlet2 regarding interoperability with M.2 SATA SSDs, as documented here:

https://fit-pc.com/wiki/index.php?title ... 2_SATA_SSD

Looking at the Fitlet2 FACET card pinout documentation, and comparing it with the M.2 specification (caution, large PDF), it appears that the conflicting pins are pins 56 and 58? Those are listed on the M.2 spec (page 134) as being reserved for MFG_DATA and MFG_CLOCK, and on the Fitlet2 pinout page as used for eMMC_RST and eMMC_strobe. The remaining pins marked as being used for the eMMC function on the Fitlet2 are marked as being unconnected (N/C) in the M.2 spec.

I have one of the affected SSDs, the Micron M600 MTFDDAY128MBF, which I had been planning on installing into my Fitlet2, so I took the opportunity to check the pins on the SSD itself:

Image

This appears to confirm that pins 56 and 58 on the SSD are clearly connected (there are visible traces leaving those pins on the PCB), whereas nothing appears to be connected to the remaining pins the Fitlet2 uses for eMMC functionality.

Looking up the details in the M.2 spec for the MFG_DATA and MFG_CLOCK pins, it says (page 136):
Manufacturing Data line. Used for SSD manufacturing only. Not used in normal operation. Pins should be left N/C in platform Socket
This means that these two pins should be unconnected (they don't need to be grounded or similar), and therefore it should be possible to carefully tape over these two pins on the SSD with kapton tape, isolating these pins from the Fitlet2 connector and resolving the issue.

While I understand that Compulab cannot take any responsibility for end-users taping over pins on their SSDs, are you able to confirm that my basic understanding of the issue is correct, and that it's only pins 56 and 58 on the SSD that are in conflict with the wiring of the Fitlet2 M.2 socket?

Many thanks!

tamir
Site Admin
Posts: 419
Joined: Mon Dec 25, 2017 4:21 pm

Re: Understanding SSD compatibility issues, FITLET2ERR008

Post by tamir »

Thank you for your inquiry.
I am consulting our R&D and will return to you asap.

tamir
Site Admin
Posts: 419
Joined: Mon Dec 25, 2017 4:21 pm

Re: Understanding SSD compatibility issues, FITLET2ERR008

Post by tamir »

Our R&D confirmed that taping the pins could work.
We are also studying if the issue can be addresses using a UEFI update. Once we have findings we will publish.

snoopstah
Posts: 2
Joined: Sat Mar 07, 2020 7:10 am

Re: Understanding SSD compatibility issues, FITLET2ERR008

Post by snoopstah »

Thanks very much, tamir!

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