Required mPCIe data signals for LimeSDR XTRX

Projects LimeSDR
1

Hello everyone,

Is it enough to have 1 PCIe lane wired to the connector, or is USB/SMBUS/I2C required as well?

The question originates from looking for a SoM for a custom carrier board, but could also become very handy when looking for a mPCIe adapters and devkits. Some of them do not route SMBUS, some of them do not route USB, possibly same goes to i2c.

P.S. Congratulations to the Lime team for the XTRX launch!

2

You can find the mPCIe connector pinout in the documentation:

https://limesdr-xtrx.myriadrf.org/documentation/board-description.html#mini-pcie-edge-connector

3

Thanks for confirming the pinout.

I am still a bit confused, though. Does it mean that for proper operation of the XTRX the carrier board must route USB and SMBUS to the connector?
Or, maybe put it this way, for demonstration purposes. Is it possible to use, say, Raspberry Pi CM4IO or the Rock 5 for prototyping with XTRX? Neither of these boards route SMBUS to the connector, and, to my memory, only Rock 5 provides USB.

Hopefully the question makes sense.

P.S. I was looking into specifications of the XCOM, and it does not have USB on the mPCIe connector. So I guess it is optional, although I understand LimeSDR XTRX might have different requirements.

4

I don’t think so, but tagging @Zack as he could say for certain.