0
\$\begingroup\$

So I have a M.2 to mPCIe adapter board that unfortunately I don't have any documentation for. The purpose of the board is to allow for a 4g M.2 modem to connect to a PC with a mPCIe slot.

Presumably by changing the configuration of R4/R5/R7 it's possible to set the card to use the USB, PCI, or SATA interfaces. For the life of me I can't tell what they mean by the X's and O's. Should I interpret either X or O as populated?

If it helps, this is the M2BU3S-U3D card from Bplus Tech: http://www.hwtools.net/Adapter/M2BU3.html

enter image description here

\$\endgroup\$
1
\$\begingroup\$

Those are configuration links.

  • X means don't connect.
  • 0 means 0 Ω so just bridge the pads with solder, a short piece of wire or a 0 Ω resistor.

It has been supplied configured for USB. If you confirm operation by USB that should confirm my statements above.

\$\endgroup\$
0
\$\begingroup\$

My interpretation here is that x is open. "O" is really a zero, implying a zero ohm jumper, or a solder bridge. The placement of R2, R5, and R7 seems like they were placed there as a user configurable option.

It's also common practice to control PCB variants through the BOM (bill of materials). It's much easier to create 1 PCB with 3 BOMs with parts that are or are not populated, versus creating 3 separate PCB designs with 3 sets of gerber files and 3 BOMs. R2, R5, R7 seem to fit this design philosophy.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.