Serial Monitor not responding

Hello. I am working on my first arduino project with my son. We are building a Vorpal Robot. I have successfully programmed the nano for the robot and the controller. I am trying to configure two HC-05 Bluetooth modules (one slave & other Master).

I wired up the Arduino Uno following the attachment I uploaded for this comment.

I have uploaded a blank sketch to the Arduino Uno.
I have HC-05 booted up to AT mode
I have set serial monitor to "Both NL & CR" & Baud rate as 38400

When I enter AT in serial monitor, I get no response at all.

Can someone please help me with resolving this issue.
Thanks in advance.

Your diagram shows your Bluetooth module connected to pins 0 and 1. Those pins are used for communication with the Serial Monitor through the USB cable.

I suggest you use SoftwareSerial to create another serial port on two other pins for your Bluetooth module.

And AFAIK you should connect Tx to Rx and Rx to Tx.

Are you sure your Bluetooth module can work with 5v - many can only take 3.3v?


Are you sure your Bluetooth module can work with 5v - many can only take 3.3v?


There is another recent post on this forum where that person reported that a voltage divider of 1K/2K must be used for the HC-05 RX pin.

The wiring diagramme is junk, and it is likely that any other information from the same source is too. I'm surprised that you could upload the code. The communication lines are in the wrong place and the wrong way round. Further, it is good practice to have a voltage divider in the Arduino Tx line but, if you haven't done that, don't panic, it probably isn't fatal.

Since you appear to want Arduino<>Arduino comms, check here
for somebody who really knows what he is doing.

If you have the on-board LED flashing slowly, 1flash/2sec, it is indeed in AT mode, but that merely means the power connections are OK. (This is actually a good start) Pretty well all HC-05s that are on a breakout board as you show run on 5v power, and most are marked accordingly on the back of same.

OK, I will give it a shot. Thank you. I am very new at this so please excuse my ignorance.