---
title: "W5300 vs W5300 connection link problem"
url: "https://maker.wiznet.io/forum/10713"
markdown_url: "https://maker.wiznet.io/forum/10713/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "Alex"
created: "2014-12-04T22:02:20+09:00"
last_activity: "2017-05-04T08:34:31+09:00"
language: "en"
views: 1650
replies: 4
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W5300 vs W5300 connection link problem

## Question

Asked by Alex on 2014-12-04 in Ethernet Chips.

Hi,
i have 2 modules with W5300 chip in one rack, so they have equal power, reset timings and behavior.
Each W5300 chip is used in MACRAW mode.

I noticed no Link signal when they are directly connected after power on or system reset . This is a very often situation.
When connecting to switch or notebook Link is alway ok. Connecting them after other devices disconnection is also always ok.

I could solve this problem partly by applying a delay about 30 - 50 msec before hardware reset of w5300 chip on one of modules.

Each module must be equal with the same software.

How can i solve this problem?

Thank you!

## Replies

### Reply 1 by hjjeon0608, 2014-12-08

Hi,

I tested about your issue but all link has no problem.

Plz, attach your schematic in this post.

### Reply 2 by Alex, 2014-12-09

Hi,
schematic in attachment.
There are Bourns TBU protectors in tx, rx cirquits between RG connector and transformer (~10 Ohm resistance).
I tested with removed protectors. No changes in behavior.

[![](https://maker.wiznet.io/forum_uploads/wiznet/original/1X/e4a2f03ce20b38263834bb15b6d64ae7271be86f.jpg) 1333×648 185 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/1X/e4a2f03ce20b38263834bb15b6d64ae7271be86f.jpg)

### Reply 3 by Alex, 2014-12-09

Hi,
More W5300 schematic part in attachment.

I have made a few more researches.

After power on and reset when cable is unplugged on oscilloscope i can see autonegotiation Fast link pulses sequence 2 ms length with period of 16 ms. On tx and on rx pin (because of auto MDI/MDIX i think).

After this i connect second W5300 module with straight ethernet cable and after power on take an oscilloscope.
And now i can see second Fast link pulses sequence from the second W5300 module. Two sequences are synchronously
but shifted for ~1 msec so one sequense is partly covered by the other. And this shift is drifting until sequenses are not covered any more. This takes about 50 - 53 seconds. After this appears link signal.

What can you say about this problem?

[![](https://maker.wiznet.io/forum_uploads/wiznet/original/1X/e87d83eb6817a4dd8ce8f35b9f5a45a9249a8ba9.jpg) 992×760 204 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/1X/e87d83eb6817a4dd8ce8f35b9f5a45a9249a8ba9.jpg)

### Reply 4 by jeongsk, 2014-12-11

Hi~
The circuit is no big issues. Have you ever Power-on-Reset did apply?
If you do not correctly Reset, the link may fail to occur. Reset secure a lot of time.
And if the link is successful late, Ethernet PHY fixed setting and testing.
Another way, the Ethernet line protection circuitry is removed and tested.
Thanks.

---

Source: https://maker.wiznet.io/forum/10713