---
title: "W5100 affected by noise"
url: "https://maker.wiznet.io/forum/13886"
markdown_url: "https://maker.wiznet.io/forum/13886/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "jimb"
created: "2020-06-12T19:14:16+09:00"
last_activity: "2020-06-17T01:05:50+09:00"
language: "en"
views: 507
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W5100 affected by noise

## Question

Asked by jimb on 2020-06-12 in Ethernet Chips.

Hello,

I am troubleshooting a problem with a product that uses the W5100 and an ATmega CPU to implement a Modbus/TCP server. I think noise glitches are getting into W5100 reset line, causing loss of communication.

Strangely, it still responds to ping messages, but stops responding to TCP messages or connection requests. A sanity check of reading back the MAC address from W5100 shows the address is okay, but still suspect noise on reset line, or possibly SPI bus.

A couple questions:
Could an extremely short glitch on reset line (shorter than 2usec) affect only a part of the W5100 and not another part?

If I do a reset and reconfigure it to make it recover, is doing a soft reset just as good as doing a hard reset? Does a hard reset do something not done by a soft reset?

Any thoughts are appreciated,
jimb

## Replies

### Reply 1 by bangbh, 2020-06-17

Hi jimb
If a reset occurs, ping also shouldn’t work because it loses every network information.
Please try to read the network information when it loses connection.

Thanks.

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Source: https://maker.wiznet.io/forum/13886