Arduino + Bluetooth Module Bringup

The Plan

I wanted to add Bluetooth communication capabilities to my Arduino projects.  I found a $5.01 Bluetooth module here…  This post shows the basic setup I did to get communications started.

The Hardware Setup

The voltage for the module from the supplier listed above was set for 3.6V – 6V so the Arduino 5V supply output is ok.

I found the data sheet for the HC-06 module here:  Unfortunately the Tx and RX voltage is 3.3V still so I also purchased a cheap $1.82 level shifter here:

For the basic communication, I just hooked up the TX and RX through the level shifter to a SW UART on my Arduino UNO.  Here is the Fritzing diagram…


DIAGRAM UPDATED: Someone noticed that I had the HV and LV supply reversed in my original diagram.  I have corrected it.

Note: I used a HC-05 Fritzing symbol here (only one I could find).  The State and Key pins are not there on my HC-06 module.  Not sure what they should be connected to if it were a HC-05.

The Arduino Code

For the basic test, I am just using a basic pass through Arduino sketch…

 Software serial test
 Receives from the hardware serial, sends to software serial.
 Receives from software serial, sends to hardware serial.

#include <SoftwareSerial.h>

SoftwareSerial mySerial(7, 6); // RX, TX

void setup() 
 // Open serial communications and wait for port to open:


void loop() // run over and over
 while (mySerial.available()>0 )
 while (Serial.available()>0 ){

The Initial Test / Debug

I uploaded the Arduino sketch and opened the serial monitor and tried to send “AT” to the module.  Nothing came back.  Google’d around and found this post  One of the comments in the post said that you can’t send NL or CR in the serial communication to the HC-06 module.  Changed the serial monitor settings…


Once I changed the serial monitor to not send any line ending, I was able to send AT+VERSION and get the response in the above screen capture.  Sending any line ending character resulted in no response.

The Next Post

I was able to Bluetooth pair the HC-06 with my Android tablet and write an Android app to send text back and forth to the Arduino.  That will have to be covered in a separate post.  I will post those development steps in my next blog post tomorrow (or sometime soon).


3 thoughts on “Arduino + Bluetooth Module Bringup

  1. In your fritzing you say the 5v side of logic level converter goes to HC-06 and the 3.3v side to Ardu… other way round, is not it? or am I wrong :)? And THANK YOU for your blog sharing knowledge … waiting for your nexts posts


  2. Pingback: Simple Android to Arduino Bluetooth Communication | PetesTechProjects

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