---
title: "Issue Config Tool Fw update"
url: "https://maker.wiznet.io/forum/13186"
markdown_url: "https://maker.wiznet.io/forum/13186/md"
type: "Forum topic"
category: "Serial-to-Ethernet & ConfigTool"
author: "Alessio Lama"
created: "2019-01-29T10:23:28+09:00"
last_activity: "2019-01-30T23:28:03+09:00"
language: "en"
views: 557
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# Issue Config Tool Fw update

## Question

Asked by Alessio Lama on 2019-01-29 in Serial-to-Ethernet & ConfigTool.

Hi, I have a custom hardware based on WIZ750SR , this works with official FW version 1.2.4, I built a FW with Keil based on [GitHub - Wiznet/WIZ750SR: WIZnet Serial to Ethernet(S2E) module based on W7500 chip, WIZ107/108SR S2E compatible device](https://github.com/Wiznet/WIZ750SR) - tag v1.2.4 . If I update the FW with config tool the device is bricked , If I update with SWD works and next works also with config tool. I think that the issue is related to the APP flash address but I’m not sure. Please can you help me

Regards

## Replies

### Reply 1 by jameskim, 2019-01-30

Hi,

WIZ750SR FW consists of two parts, application boot(we call it app_boot) and application.
When you download binary with SWD or via ISP communication, you should use the whole binary which includes app_boot and application.
But when you update FW with the configuration tool, you should use the application binary only.
App_boot should be running on WIZ750SR or your own HW to upload new application via the configuration tool.

I guess you uploaded with a wrong binary.

Regards,

James.

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Source: https://maker.wiznet.io/forum/13186