---
title: "W7200 MCU is always down"
url: "https://maker.wiznet.io/forum/10244"
markdown_url: "https://maker.wiznet.io/forum/10244/md"
type: "Forum topic"
category: "General"
author: "alick3721"
created: "2014-05-19T16:41:41+09:00"
last_activity: "2017-05-04T08:32:57+09:00"
language: "en"
views: 992
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W7200 MCU is always down

## Question

Asked by alick3721 on 2014-05-19 in General.

Hello sir/madam,

I am now using W7200 MCU to develop a communication system with PC using an internal timer(TIM3). I found out that the system is always totally down, the LEDs were off and even no reponse when I pressed reset button. The only thing I can do is plug out the power supply and connect it again. In my code, I use PA2, PA3, PA8, PA11, PA12, PB2, PB5, PB6, PB7, PB10, PB11 and PB12 as the output pins, and use PA13, PA14, PA15, PB13, PB14, PB15, PC14 and PC15 as the inputs. Would you please give me some suggestion about where the problem should be?

Thanks,
Rui

## Replies

### Reply 1 by alick3721, 2014-05-20

What is un-registered ISR and Hardfault ISR?

## Thanks.

[quote=“midnightcow”]Hi,

I wonder what is your problem? Do You hope led-toggle by using the internal timer TIM3 ? Am I right?

If W7200 be always down, your source code have a some problem.
Check the warning message in complier & analyze the log to be printed out on running code.

In my experience, It maybe halted in un-registered(default) ISR routine as Hardfalut ISR.

Thank you.[/quote]

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Source: https://maker.wiznet.io/forum/10244