HC05 not returning anything from AT commands

I've been trying to use two HC05 Bluetooth modules to have two Arduino send data back and forth. I'm using an Arduino Uno, and I've wired it to the module following this tutorial.

Baudrate is set to 38400, and both BL & CL is selected.
I've wired up my first Arduino, and the light is flashing every 2 seconds, which I'm pretty sure suggests that it's in AT command mode. I want to set it to master mode, so first I entered AT in the serial terminal but didn't get a reply from the module. Any idea of what I did wrong?

hi, @leonwoodland
Welcome to the forum.

Please read the post at the start of any forum , entitled "How to use this Forum".

This will help with advice on how to present your code and problems.

Have you got the baud rate in the Serial Monitor set to the serial baud rate of the HC05?

Can you please tell us your electronics, programming, arduino, hardware experience?

Tom... :smiley: :+1: :coffee: :australia:

Not everyone might want to watch the whole Video to find out what might have gone wrong...

So, you've uploaded an empty sketch, seems fine
Did you set connect the BT-Module to TX0 and RX0 the right way after programming?
Did you set the module in AT-Mode and did it blink the way it should?
Did you set the speed of your communication to 38600kbit/s (it's 115200kbit/s by default)?

Please provide a detailed list of steps of what you did, how you wired it, what you expect and what you got.

best regards, Marco

Hi, thanks for the reply. I fixed my questions following the guidelines as much as possible. I'm sorry for the vagueness of my question. I hope I've formatted it right...

Did you set the "line ending" (CR or CRLF) in the way it was suggested?
After the AT you have to press enter to get a reply.

Yeah it's set to NL & CR and I press enter after typing but I get no reply in the serial monitor.

Can you post the codes that YOU are using please?

Tom.... :smiley: :+1: :coffee: :australia:

here's the code. it's just an empty sketch tho

void setup() {
  // put your setup code here, to run once:


void loop() {
  // put your main code here, to run repeatedly:


Okay, now post a drawing of how you have the HC05 connected to your controller.
Reverse engineer YOUR project and draw a circuit of it and post a pic.

A picture of your project would also help.

You do not have to use a CAD program, just your HandCAD.

Thanks... Tom... :smiley: :+1: :coffee: :australia:

Heres the circuitry
The resistor values are 1k and 2k ohms


I´ve already read here some warnings about trusting on YT tutorials. But I would give it a try:

There are some tutorials that says when you´re connecting the HC-05 module directly into RX/TX pins of Arduino, in AT mode they might not be crossed.

It means: connect RX of the module to RX of Arduino and TX of the module to TX of Arduino.


A schematic to follow?

Thanks.. Tom.. :smiley: :+1: :coffee: :australia:

The reference to an empty sketch implies that you are using the UNO only for its USB interface.

It may be preferable to completely disable the ATmega328 by jumpering pins 5 and 6 (the two nearest the ATmega328 chip itself) on the ICSP header, so holding it in reset.

I'm really sorry for the late response. I've been busy with other things.
I wanted to ask, is there any recommended circuit designing software?


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