ESP8266 Community Forum

I think if you've managed to flash the firmware on it successfully, then it should be working fine, and you say that you see some output when you reset. Is the output ends with the word "ready"?

Take the arduino out of the picture. Just connect to the module using any means of USB-Serial, open the serial terminal and power up the ESP. What comes out on the screen?

Your Arduino sketch says bitrate 115600. Should be 11520?

Hi,

thanks again. I've also tested without arduino and also with the correct bitrate of 115200.

and the output i saw was only some random data, with every baudrate (115200, not 115600). and the module transmitted the data over one minute.

Currently, there is not even a single byte transmitted and the blue light is not flashing. Maybe there is a loose contact anywhere

I would check all connections thoroughly and also add good decoupling capacitors as close to the ESP as practically possible. At least one large electrolyte (the larger the better) - and in general it is a good idea to add in parallel a 100 nF ceramic, as they react faster to small ripple than the large electrolytes.

Are you certain that your USB to serial adapter outputs 3.3V signals? Some of them give 0-5V signals. 5V signals on the Rx pin of the ESP is potentially harmful. You might need to level shift the signals.