I am trying to communicate with the HC-05 Bluetooth module for quite long time now, but with no success.

I am using the Nodemcu(V3) ESP8266 module.

I connect the HC-05 to Nodemcu in following sequence:

HC-05             Nodemcu
-----             -----------
RX       -->      Pin 1 (Tx)
TX       -->      Pin 3 (RX)
Vcc      -->      +3.3V
GND      -->      GND 

For starters, i want to check if my Nodemcu is communicating properly with my HC-05 module.

I have written the following code to read the response of AT commands:

#include <SoftwareSerial.h>
SoftwareSerial BTserial(3, 1); // RX | TX
char Bluetooth_Name = ' ';

void setup() 
    // Arduino IDE serial monitor

    // HC-05 default serial speed for AT mode is 38400

    // Wait for hardware to initialize

    // Print debug string

void loop()

   // Keep reading from HC-05 and send to Arduino Serial Monitor
   if (BTserial.available())
      reading = BTserial.read();

   // Keep reading from Arduino Serial Monitor and send to HC-05
   if (Serial.available())
      reading = Serial.read();

However, i do not get response for any AT command at all. The serial monitor just shows blank.

Thanks in advance

EDIT:- I connected the "EN" pin on the HC-05 to Vcc. Now, the led on the HC-05 blinks slowly, which means that the HC-05 is configured in command mode. However, i am still not able to receive the response for any AT commands. I have also selected "Both NL & CR" in the serial monitor, configured the baud rate correctly and double-checked the hardware connections.

Everything seems to be correct except that i don't get response for the AT commands.

Please help!!!

  • what output do you get, if any – Jaromanda X Feb 15 '19 at 22:28
  • No, i did not get any output on the serial monitor – Sandrocottus Feb 18 '19 at 10:40
  • I just modified the question to check the basic step if HC-05 is working with Nodemcu or not? – Sandrocottus Feb 18 '19 at 10:46

I changed the line

SoftwareSerial BTserial(3, 1); // RX, TX


SoftwareSerial BTserial(D4, D3); // RX, TX

And got it to work!

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