---
title: "W6100 last byte becomes first"
url: "https://maker.wiznet.io/forum/13692"
markdown_url: "https://maker.wiznet.io/forum/13692/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "Mihail Balezin"
created: "2020-02-10T14:55:38+09:00"
last_activity: "2020-02-11T11:05:57+09:00"
language: "en"
views: 545
replies: 2
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W6100 last byte becomes first

## Question

Asked by Mihail Balezin on 2020-02-10 in Ethernet Chips.

Hello!

I have a quite strange problem. I send a message ‘12345678’ to the W6100 and then read form it’s buffer ‘81234567’. I just always have my last byte on the first position. If I continue sending this message I continue recieving the same result, I mean ‘81233456781234567’.

Could you help with this problem, please?

## Replies

### Reply 1 by mon2 mon2, 2020-02-10

Hi. I am new to the W6100 and about to start some new designs with this controller but thought to ask - could this be due to an internal cyclic buffer?

What if you write “1234567” and read this back - what is the result?

### Reply 2 by Mihail Balezin, 2020-02-11

Thank you for your help!

You were right, It was my mistake. My MCU operates with 80 MHz frequency, so I was sure, that there shouldn’t be any problem with bus communication with 100 MHz Wiznet. I just increased timings and now it works properly.

---

Source: https://maker.wiznet.io/forum/13692