---
title: "Simple way to test microcontroller and wiznet SPI communication"
url: "https://maker.wiznet.io/forum/14388"
markdown_url: "https://maker.wiznet.io/forum/14388/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "ODM428657"
created: "2021-11-07T01:07:40+09:00"
last_activity: "2022-03-10T15:19:54+09:00"
language: "en"
views: 856
replies: 3
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# Simple way to test microcontroller and wiznet SPI communication

## Question

Asked by ODM428657 on 2021-11-07 in Ethernet Chips.

Hello,

I’d like to run a simple SPI communication test using the ioLibrary. So far, I can read registers without any issue but cannot write to them for some reason.

Can someone tell me if there is a step that I am missing after writing to a register? Do I need to pull the chip into reset for a moment?

What I’d like to do is the following

1. Read a register value

2. Write a new value to that register

3. Read the new value back

Can someone give me a good register to test this on? Thanks.

## Replies

### Reply 1 by louis, 2021-11-12

Hello,
If you have potted Iolibrary, please try the Loopback Test. The loopback example exists inside the iolibrary_Driver/Application.

![](https://github.githubassets.com/favicons/favicon.svg) [GitHub](https://github.com/Wiznet/ioLibrary_Driver)

![](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/1/17f66f2e9c27f9749e7af3ad7efe15d9492bea3b.png)

### [GitHub - Wiznet/ioLibrary_Driver: ioLibrary_Driver can be used for the...](https://github.com/Wiznet/ioLibrary_Driver)

ioLibrary_Driver can be used for the application design of WIZnet TCP/IP chips as W5500, W5300, W5200, W5100 W5100S. - GitHub - Wiznet/ioLibrary_Driver: ioLibrary_Driver can be used for the applica...

Thank you.

### Reply 2 by ODM428657, 2021-11-13 (in reply to reply 1)

Louis,

Thanks for the feedback. This is a bit more than what I am looking for, however. I wrote a simple program to read a register and write to a register. I want to read a second time to make sure the data is updated.

Can you give me a good register to test this on? I know some bits are write-protected in certain registers.

### Reply 3 by Mert Gulsoy, 2022-03-10

I think you can try SIMR. The socket interrupt mask register.

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Source: https://maker.wiznet.io/forum/14388