I try to connect Ardunio Mega with ESP8266 wifi module. Wiring diagram mentioned below: enter image description here

I am using Ardunio IDE - For AT command test I was open COM monitor and selected 115200 baud rate and set to Both NL & CR.

But no response from ESP8266 wifi module. Response like "System read Vendor". I have changed different baud rate. But no use of it.

I don't know what I am missing out.

Please help on this.

Thanks, Shanmuga Raja


1 Answer 1


Your ESP8266 module is most likely fried now, if your wiring diagram is any indication of your actual hardware setup.

The ESP operates at 3.3V, which means that every pin on it can receive no more than 3.3V as input. And it looks like you've directly connected the ESP's TX pin with the Arduino, without using a level shifter. The Arduino GPIO pins work on 5V logic levels.

Test this module out with a level shifter (resistor divider network, 3.3V zener, level shifter IC; pick your poison). If the ESP still doesn't respond, swap it out with a new one and repeat.

  • 1
    esp8266 io pins are 5V tolerant. I and many others connected 5V signals to them
    – Juraj
    Mar 26, 2018 at 14:02

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