WIZ750SR-TTL does not work anymore

It’s the first time I use so a module.
After configuration with S2E V1.4.0 and WIZ750SR-EVB (TTL-RS232) the module worked as expected.
A few hours after functioning without problem in my project, it no longer works and only the red led is still on.
So I put it back on the EVB and there no longer any response. It seems that he has lost all his configuration. On the S2E, it’s no longer detected either with the IP address I gave it or the factory one. No message on the debug port either.

An idea ?


I guess your module is damaged.
I don’t know the exact reason either.
If you send me your circuit, I can ask the hardware team to review it.
First of all I recommend that you rewrite the firmware.
Please refer to the isp tool link and the firmware file link.


Hello Becky,

Thanks for fast answer.

I found w7500_isp_20180731 and his wiki. I followed this procedure, uploaded boot + firmware 1.3.3.

The module works again but after exiting ISP mode and reset it the message ‘INPUT FIRST MAC?’ appears on terminal.

So after searching on your web page, I used the MAC Tool V20151127 to set the same MAC Address as before. The module works now perfectly.

Question: In my project, I reset the module on startup by using the ‘nReset’ pin. Could this be the reason of this issue?

Remark: It’s not the first case of this trouble. Becoming a first module from my dealer (Comet Electronics, Bulgaria) it was the same. They sent me another one with the same MAC Address and I sent back the faulty module. Today, I didn’t have any feedback about the problem.

Thanks for your support.