---
title: "W5500 read constant value"
url: "https://maker.wiznet.io/forum/15087"
markdown_url: "https://maker.wiznet.io/forum/15087/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "Null-X"
created: "2023-12-06T21:17:07+09:00"
last_activity: "2023-12-12T09:19:39+09:00"
language: "en"
views: 122
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W5500 read constant value

## Question

Asked by Null-X on 2023-12-06 in Ethernet Chips.

Hello, i recently bought my W5500 chip and testing it on STM32F401RE, and everything works if i connect it to SPI1 (42MHz), but when i connect it to SPI2(21MHz), when i try to read data, it returns constant value of 3 and sometimes the correct data gets received. Write access is working normally. And if i lower the SPI2 speed a bit, there is constant 3 every time i try to read. I tried to read from all register addresses but all returns just 3.

Sorry for bad english
I really appreciate your help.

## Replies

### Reply 1 by Eugeny, 2023-12-06

I am afraid you need a scope or logic analyzer to see what is going on the SPI lines.

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Source: https://maker.wiznet.io/forum/15087