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Over many years and device generations Samsung SSD have featured a set of internal contacts. On the image below, i mean the row of 7 "plated holes" at the top center of the image.

Can anybody tell me with certainty what they are? And if so, what their pinouts are?

enter image description here

Hennes
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ARF
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    Nobody would be able to tell you ( with certainty ) the holes are for without detail technical specifications and perhaps even a circuit diagram. Lookiing at the picture they are connected to the rest of the circuit. – Ramhound Feb 01 '13 at 18:41

3 Answers3

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I was looking to see if there is any way to debug samsung SSDs and I stumbled upon this thread. I managed to figure out what the pins are. It is in fact JTAG. The pinout is as follows:

  • gnd
  • tdo
  • tdi
  • tck
  • tms
  • [tiny gap]
  • vref?
  • unknown

vref is 1.8v

Seems to be the same for all Samsung models I ran into. Even NVMe models.

Posting it here to save the rest of the world some effort.

Giacomo1968
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carlicious
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I can confirm gnd, tdo, tdi, tck, tms and the [tiny gap] vref? and unknown provide the SAFE mode when shorted during boot.

In SAFE Mode, there is a UART interface (FTDI style) with a IN and a OUT pin nearby, after the big gnd ring. On the other side I was able to identify 1 pin that goes to pin11 on the SATA power adapter, what the other 5 pins are, I dont know.

The UART might allow reflashing the hardware. Search for “The missing Samsung EVO 840 - 250 GB Repair Manual” for more details.

Giacomo1968
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Sourcerer
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5

Only a Samsung engineer could tell you with certainty, and their employer would most likely prohibit it due to the proprietary nature.

In general, undocumented interfaces like that on circuit boards are used for development and acceptance testing purposes. They usually consist of a JTAG or other sort of in circuit programming/debugging interface. It's used to program the firmware and unique serial numbers at manufacture time, as well as to test for proper soldering and electrical functionality. There may also be a serial terminal interface for viewing boot and other log messages for troubleshooting and development purposes.

Sometimes engineers put extra connections purely for prototyping purposes. They want to be able to experiment on a new part or something, but PCBs are expensive to produce, so they will build flexibility into the board. Because they don't want to redo layout and everything, those vestigial connections might remain on the board even though the experiment has concluded.

Karl Bielefeldt
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    This is the most likely explanation. It's probably used for programming the device firmware and serial number and automated testing using boundary scan. – David Schwartz Feb 01 '13 at 20:00
  • Karl I agree with you that they are likely diagnostic/manufacturing in nature. Though I was hoping for an answer that gave the specifications to allow reflashing the firmware. Thanks anyway. – ARF Feb 01 '13 at 20:52