Arduino AND Bluetooth HC-05 Connecting easily

Picture of Arduino AND Bluetooth HC-05 Connecting easily

Hello Every body , This is my first artical on , I'm so happy for that , and I will start by How to connect arduino with bluetooth , I suffered a lot of problems when I try to connect it as the website and instructable artical did , So i decided To share my experience with You

The bluetooth module I will use today is HC-05 which is so familiar and cheap ,

Most tutorial on The website Connect the bluetooth with default Rx and Tx on the arduino Board , I faced a lot of problem and bluetooth didn't work will .

But arduino  support something Called Software Serial , which allow You to change any arduino board pin to serial pin

so After reading this article you will be able to:

1) Connect arduino Board with PC By Bluetooth , to send and receive data .
2)Connect arduino Board with Any android device .

so you can send your information , Like Sensors reading , from arduino to PC Or android device , and you can build your Home automation system by bluetooth , and controlling your robot wirelessly

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Step 1: Material and connection

you need to do this experiment :

1) Arduino Board " I used Arduino Uno ".
2) Bluetooth module HC-05.
3)Solderless jumper.
4)Bread Board .
5)Battery 9V "Optional".

The connction between  Arduino and bluetooth is like the schematic above 

sunxing2210 months ago
well done , thanks for this tutorial
please do not forget to post this tutorial in your blog in Arabic :)
ehmedat19 days ago

If allowed possible code transmitter via Bluetooth

santan0071 month ago

Done the connections in exactly the same manner, also used the same sketch, still doesnt work for me. Neither with android nor TeraTerm.
Please help. What could be the possible problem?

santan0071 month ago

Done the connections in exactly the same manner, also used the same sketch, still doesnt work for me. Neither with android nor TeraTerm.
Please help. What could be the possible problem?

zx lee2 months ago

For HC05 there are 6 pins, state, Rx, Tx, GND, Vcc and EN. I just need to connect 4 (Rx, Tx, GND, Vcc) to interface with Arduino?

Goines3 months ago

Great tutorial, definitely helped get my HC-05 working.

One question though; how do you get Windows to auto-reconnect to it? Once the power goes off on my HC-05 I have to delete the device and rediscover it. It seems that Windows doesn't want to repair with it. Are other devices different in this regard?

Thanks a lot

morinel5 months ago
Hi again, when I trying step 2, Why I faced this screen on TERA TERM: What should ó is?What is the meaning?
morinel5 months ago
Hi, While I am using this instructions, I faced an error. There is nothing on my TERA TERM screen, even though I connected my bluetooth module successfully. In the video, how can you see the writes:"Bluetooth On please press 1 or 0 blink LED" I can't see this sentence on my TERA TERM? Where is my faulty?
abharath8 months ago
A beautiful work sir! thank you ..and all the best!
GeekLite9 months ago
This Instructable by A1R published in 2011 shows the proper way of wiring the same project to the same Bluetooth module to avoid any potential 3.3V problems.
imjosh10 months ago
Mohannad, I think I know what you're talking about with the 3.3v. Are you using HC-05 and Nokia modules off ebay? These seem to come with more components than the sparkfun etc versions and claim to be 5v tolerant. I wasn't sure on the Nokia based on a lot of different forums, it's very 5v intolerant. But, it didn't work correctly when I ran it on 3.3v but worked fine on 5v. I think (and I'm guessing a bit) this is caused by one of two possible problems 1) The arduino's 3.3v rail can't supply enough current or 2) The breakout circuit allows 5v logic only with 5v supply- that is if you supply 3.3v to vcc, but use 5v logic it doesn't work. But, I dunno.

Also, I found w/ an ebay/chinese hc-05 breakout didn't work when connected to the hardware serial (rx/tx) but worked fine when I tried softwareserial on some digital pins. I wish I understood why. I was supplying power via usb, so I'm not sure if that had something to do w/ it either hooking the uart to the usb cable? or what. I wasn't running the serial monitor or anything, just using the usb power.

hackmack9810 months ago
Mohannad, You got it wrong. A 10K ohm resistor in series with Tx and Rx will not shift or drop the voltage to 3.3V as you proposed in your comment. Resistors in series only limit the current but not the voltage. You can use resistors in a voltage divider to drop the voltage.
pictux10 months ago
hi, here:
there's a complete guide (in italian) to use HC-05 and HC-06 bt module (without breakout board) , from hardware connections to AT programming to serial communication.

And about Arduino TX -> BT module RX, you need a voltage divider or a simple 2k2 resistor in series.
Mohannad Rawashdeh (author) 10 months ago
this module comes with breakout which is have 3.3 regulator , so you can power it on from 3.3 or 5V , iif you operate the HC05 Breakout on 3.3V it will doesn't work probely why ?
For shift level problem , a 10k ohm resistor connected in series with Tx and Rx .

same problem I faced with LCD Nokia5110, It's also works on 3.3V and arduino Uno support 5V Logic level , look how sparkFun electronics solve this issue
the Chines LCD nokia5110 works on 5V for same thing , 10K ohm pull up resistor .

Hope If i said something wrong told me about please , thank you so much .
Mohannad Rawashdeh (author) 10 months ago
sunxing22 : Sure i will , thank you
JimElectro10 months ago
It's a big mistake to operate the HC-05 without dropping the Arduino's 5V TX signal to 3.3V. This Bluetooth module may work for a while but eventually will malfunction. You are confusing the the 3.3V regulator on the breakout board with circuit wide 5V to 3.3V conversion which does not exist. the HC-05 is not 5V tolerant. The Arduino can handle the 3.3V signal from the HC-05 but the HC-05 cannot handle Arduino's TX 5V simply because it was not designed for 5V. This maybe the easy way to wire it but it's not a sound engineering practice.

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