Questions Regarding PCIe Mode Support and Ethernet Port Conversion Feasibility of the LTE-A EM160R-GL Module

IoT Modules LTE-A Module
1

Hello. I would like to know whether the PCIe mode of the LTE-A EM160R-GL module supports RC mode. I am hoping to install it on a network adapter board with an RTL8125BG chip to route out an Ethernet port for use. The RM500Q series has been successfully used on this adapter board before.

I would appreciate help and answers from relevant technical support personnel. Thank you.

2

Dear Customer,

Thanks for your question.

For the EM160R-GL, the PCIe interface is implemented as an Endpoint (EP) only. It does not support Root Complex (RC) mode.

In a PCIe system, you always need a Root Complex to handle link bring-up, enumeration, and configuration. Since EM160R-GL is an endpoint device, it depends on an external host (e.g. CPU/SoC) to play that RC role.

In your case, the RTL8125BG is also a PCIe endpoint. So connecting:

EM160R-GL (EP) ↔ RTL8125BG (EP)

won’t work, because there’s no RC in between to manage the bus. PCIe doesn’t support endpoint-to-endpoint direct communication.

Regarding your experience with RM500Q typically in those setups there’s either:

  • a host platform acting as RC in the system, or
  • the design is using another interface path (USB/RGMII) rather than PCIe between devices

So for your intended Ethernet output, you’ll need one of the following:

  • a host SoC/CPU with PCIe RC to connect both devices, or
  • use EM160R-GL over USB (MBIM/QMI) and bridge to Ethernet via software, or
  • consider a module that provides a native Ethernet interface (RGMII/SGMII)

Basically, EM160R-GL itself cannot act as RC, so it can’t directly control or interface with the RTL8125BG over PCIe.

3

Thank you very much for the detailed and professional explanation.
I now understand the PCIe RC/EP limitation and will explore the USB or host-based alternatives you suggested.
Much appreciated!