ESP8266 Community Forum

Hi!

I'm trying to flash three different ESP8266 modules using ESP Flash Download Tool and NODEMCU Firmware Programmer but it fails on

Writing at 0x00000000 ... (0%) error when download firmware)

or

Error:Write flash timeout.

I assume that UART connection is working well because I get MAC addresses. GPIO0 is connected to the ground.

What can cause the problem?

Thanks!
Patriko

I'd tried another app - ESP8266 Flash Downloader and the result is similar:

connecting ....
Erasing flash...

Writing at 0x00000000... (0 %)

Writing at 0x00000400... (0 %)

Writing at 0x00000800... (0 %)

Writing at 0x00000c00... (0 %)

Writing at 0x00001000... (0 %)
Failed to write to target Flash

Problem solved. Serial port optoisiolator which I used since burning my PC was not working correctly with 3.3V (designed for 5V).