---
title: "Connecting PHY interface to PHY interface"
url: "https://maker.wiznet.io/forum/15581"
markdown_url: "https://maker.wiznet.io/forum/15581/md"
type: "Forum topic"
category: "MCU & Boards"
author: "mohitsingh2806"
created: "2025-02-13T13:10:06+09:00"
last_activity: "2025-02-17T14:34:33+09:00"
language: "en"
tags: ["W5500"]
views: 5
replies: 2
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# Connecting PHY interface to PHY interface

## Question

Asked by mohitsingh2806 on 2025-02-13 in MCU & Boards.

Hi,

In a new design I need a Serial to Ethernet module with two ethernet ports.
The microcontroller is ATMEGA2560 and I am using Wiznet W5500 IC with it.
For having multiple ports I have selected a microchip KSZ8794CNXIC to act as a ethernet switch.
Now W5500 cannot connect to the switch IC over MII interface and has to connect over PHY as I understand.

My question is this: Can I connect (ATMEGA+W5500+Magnetics) to (Magnetics + PHY Port1 of KSZ8794CNXIC).

It is like a LAN connection but without the RJ45 and ethernet cable.

Will this configuration work?

Or a configuration where we have capacitive coupling between the two? Has anyone worked on capacitive coupling with W5500 before?

## Replies

### Reply 1 by mohitsingh2806, 2025-02-13

> It is recommended to consult with an experienced hardware engineer or refer to application notes and design guides from both WIZnet and Microchip to ensure that your design will function correctly and reliably. If you need further assistance or specific design recommendations, you might consider reaching out to the WIZnet community or technical support for more detailed guidance.

This is what I need.

### Reply 2 by jaden, 2025-02-17

Hi

You can connect (ATMEGA+W5500+Magnetics) to (Magnetics + PHY Port1 of KSZ8794CNXIC) with PCB routing.

Please route as differential pairs, ensuring that proper spacing between the TX and RX lines, just like when routing the MDI lines.

If you want to review your PCB, send me your gerber file.

jaden@wiznet.io

Thanks

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Source: https://maker.wiznet.io/forum/15581