user32602: I have a bluetooth module HC-06 and want to pair it to my Arduino UNO. The thing is when I researched how to do so, I got different answers. What pairing should I use? Thank you in advance. I have highlighted the differences.
First version:
https://www.instructables.com/id/Add-bluetooth-to-your-Arduino-project-ArduinoHC-06/
HC-06>>>Arduino
VCC>>>>3.3v
GND>>>>GND
TXD>>>>RXD
RXD>>>>TXD
Second version:
http://42bots.com/tutorials/hc-06-bluetooth-module-datasheet-and-configuration-with-arduino/
HC-06            <<>> Arduino
HC-06 Ground GND <<>> GND
HC-06 VCC pin  <<>> 5v
HC-06 TX/TXD pin <<>> Arduino RX
HC-06 RX/RXD pin << resistors >> Arduino TX
[![enter image description here][1]][1]
[![enter image description here][2]][2]

user4143: Which you use depends on two factors: the HC-06 carrier board you have, and which Arduino you are using.
If your carrier board has (and most do) a 3.3V regulator then you power the board from 5V.
If your Arduino is a 5V Arduino (such as an Uno) then you need a voltage divider on the (arduino)TX->(hc)RX pins otherwise you risk damaging the bluetooth module. 

32602: <p>I have a bluetooth module HC-06 and want to pair it to my Arduino UNO. The thing is when I researched how to do so, I got different answers. What pairing should I use? Thank you in advance. I have highlighted the differences.</p>

<p>First version:
<a href="https://www.instructables.com/id/Add-bluetooth-to-your-Arduino-project-ArduinoHC-06/" rel="nofollow noreferrer">https://www.instructables.com/id/Add-bluetooth-to-your-Arduino-project-ArduinoHC-06/</a></p>

<p>HC-06>>>Arduino</p>

<p><strong>VCC>>>>3.3v</strong></p>

<p>GND>>>>GND</p>

<p>TXD>>>>RXD</p>

<p><strong>RXD>>>>TXD</strong></p>

<p>Second version:
<a href="http://42bots.com/tutorials/hc-06-bluetooth-module-datasheet-and-configuration-with-arduino/" rel="nofollow noreferrer">http://42bots.com/tutorials/hc-06-bluetooth-module-datasheet-and-configuration-with-arduino/</a></p>

<p>HC-06            &lt;&lt;>> Arduino</p>

<p>HC-06 Ground GND &lt;&lt;>> GND</p>

<p><strong>HC-06 VCC pin  &lt;&lt;>> 5v</strong></p>

<p>HC-06 TX/TXD pin &lt;&lt;>> Arduino RX</p>

<p><strong>HC-06 RX/RXD pin &lt;&lt; resistors >> Arduino TX</strong></p>

<p>[![enter image description here][1]][1]</p>

<p>[![enter image description here][2]][2]</p>
 4143: <p>Which you use depends on two factors: the HC-06 carrier board you have, and which Arduino you are using.</p>

<p>If your carrier board has (and most do) a 3.3V regulator then you power the board from 5V.</p>

<p>If your Arduino is a 5V Arduino (such as an Uno) then you need a voltage divider on the (arduino)TX->(hc)RX pins otherwise you risk damaging the bluetooth module. </p>
