---
title: "w5500 arduino comunication problem"
url: "https://maker.wiznet.io/forum/13982"
markdown_url: "https://maker.wiznet.io/forum/13982/md"
type: "Forum topic"
category: "IO Modules"
author: "mortaza kasiri"
created: "2020-08-19T21:14:26+09:00"
last_activity: "2020-08-27T23:06:46+09:00"
language: "en"
views: 573
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# w5500 arduino comunication problem

## Question

Asked by mortaza kasiri on 2020-08-19 in IO Modules.

Hi I have two w5500 chinese ethernet module. one of them somtimes work and somtimes doesnt work. arduino says ethernet shield was not found. I think it is a spi problem but somtimes works good
i thing ethernet module could have spi frequency problem or oscillator problem
or cs pin and rst pin pull up.

am i right ?

how can i test According to Probable problems?
I use ethernet.h library

## Replies

### Reply 1 by irina, 2020-08-27

If you bought a module that we didn’t sell, I can’t say that it can work.
Because the schematic is unknown.

I think you should check the SPI waveform with an oscilloscope.
Please capture the waveform that reads the Mac address and upload it, and I’ll check it with you.

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Source: https://maker.wiznet.io/forum/13982