Hi Carolyuu,
Thanks. But you give a different solution from a previous post which just checked similar question as my question,
https://forums.developer.nvidia.com/t/rgmii-lines-terminations-resistors/251580
Under the posted question there was an answer to it that should follow the Design guide to make custom design, and there are no external termination resistors.
I don’t know which is the exact answer for my quesiton?
Best regards,
Ken
carolyuu via NVIDIA Developer Forumsnotifications@nvidia.discoursemail.com 在 2025年11月5日 周三 10:49 写道：
| carolyuu Moderator
November 5 |
- | - |
*** Please note that this reply is generated by LLM automatically ***
The Jetson Orin NX Series and Jetson Orin Nano Series Product Design Guide does not provide explicit information about the termination resistors for the RGMII interface on the Jetson AGX Orin SOM module. However, it does provide some guidance on the unused interface terminations.
According to Chapter 14 of the guide, unused multi-purpose standard CMOS pad interfaces, including GPIO, I2S, PCIe, UART, and SPI, can be left unconnected if not used. However, it does not specifically mention the RGMII interface.
In the case of the RGMII interface, it is a common practice to use termination resistors on the transmitter (TX) side to match the impedance of the transmission line and prevent signal reflections. The value of the termination resistors typically depends on the specific application and the characteristics of the transmission line.
Since you already have termination resistors mounted in series with the PHY RX of the RGMII interface, it is likely that you will also need to add termination resistors in series with the Jetson AGX Orin SOM module RGMII TX pins. However, without specific guidance from the design guide, it is recommended to consult the datasheet of the Jetson AGX Orin SOM module and the external ethernet PHY IC to determine the recommended termination resistor values.
Additionally, you may want to consider the following:
- Check the impedance of the transmission line and the characteristic impedance of the RGMII interface to determine the required termination resistor value.
- Verify that the termination resistors are properly sized and rated for the expected signal levels and frequencies.
- Ensure that the termination resistors are placed close to the Jetson AGX Orin SOM module RGMII TX pins to minimize signal reflections and noise.
In summary, while the Jetson Orin NX Series and Jetson Orin Nano Series Product Design Guide does not provide explicit guidance on the termination resistors for the RGMII interface, it is likely that you will need to add termination resistors in series with the Jetson AGX Orin SOM module RGMII TX pins. Consult the datasheet of the Jetson AGX Orin SOM module and the external ethernet PHY IC to determine the recommended termination resistor values.
*** Please give the thumbs up if you get answers you like. Or provide feedback to help us improve the answer. ***