Use this forum to chat about hardware specific topics for the ESP8266 (peripherals, memory, clocks, JTAG, programming)
User avatar
By Vishnu Gvv
#78164 Hello,
I have ESP 01 module, and it is connected with ARDUINO UNO. I have wired my ESP to Arduino as below
ESP - Arduino
VCC - 3.3 V
CH-PD - 3.3 V
TXD - digital pin 2
RXD - digital pin 3

and the program used here is

#include <SoftwareSerial.h>

const byte rxPin = 2; // Wire this to Tx Pin of ESP8266
const byte txPin = 3; // Wire this to Rx Pin of ESP8266

// We'll use a software serial interface to connect to ESP8266
SoftwareSerial ESP8266 (rxPin, txPin);

void setup() {

//You may need to uncomment this block for the first run:
// ESP8266.begin(115200); // Change this to the factory baudrate used by ESP8266
// delay(1000);
// Serial.println("Setting BAUDRATE to 9600");
// ESP8266.println("AT+IPR=9600");


bool okReceived = false;

void loop() {

if (Serial.available() > 0)
String command = Serial.readStringUntil('\n');
Serial.println("Command Sent: " + command);

int responseCounter = 0;
if (ESP8266.available() > 0)
while (ESP8266.available() > 0)
if (responseCounter == 0)
Serial.println("Response Received:");

String response = ESP8266.readStringUntil('\n');


The module worked fine for the first time, and it has received the AT commands and responded back. When I powered off and again powered on the ESP module it seems not responding to AT commands and blue and red LEDs are constantly ON.
I kindly request the reader to help me with this issue, Thanks in advance
User avatar
By QuickFix
#78211 Looks like you've blown up your ESP. :(

Please note that the ESP works on 3.3V only (this includes both VCC as GPIO): it's not, I repeat not 5V tolerant.
An Arduino works with 5V levels and will eventually fry your ESP when you directly connect Arduino I/O pins to the I/O pins of the ESP without level conversion (even a simple voltage divider might suffice).

Please note this thread from a couple of days ago, of someone with a similar problem. :idea:

As another tip (it's also in my signature for a reason): when you're new to the ESP, first get yourself a development board; it will make your life so much easier and a complete board is equally cheap as a separate ESP-module.

Also the ESP8266 is a magnificent chip which is (at a lot of points) more powerful than an Arduino; most applications can be made with only an ESP without the use of an Arduino at all.
Since communication over AT is cumbersome not having to interface two microcontrollers is a big plus as well.

And the best part is: you can also write code for the ESP with the Arduino IDE and ESP-core. :idea: