How to communicate between Raspberry and Arduino over Bluetooth

Use an Arduino UNO to communicate with a Python program on Raspberry over Bluetooth:
I used the RN42-XV Bluetooth Module, Raspberry 3 with OS 2017-09-07-raspbian-stretch and Arduino UNO.
You can find more infos and the programs on my homepage:

Additional:
I have made an example how you can connecting the Bluetooth automatically:

[userdc]

Thanks, worked perfectly with esp32 as well

[pdpanchal]

Thanks for this video Sir. Your explanation is very good in above video. Do you have any video for interfacing fingerprint sensor with pi ?

[arthurcuney]

Thanks for your video it was a great help

[gonzalorivera]

Your video is really helpful, sir! I have a question, you are connecting manually the bluetooth of the raspberry and the arduino, is there any way to connect automatically the bluetooth between arduino and raspberry inmediately after they both turn on? Thank you

[izzuddinisa]

hello sir, what is the difference between HC-05 and RN42? base on what i search. the difference is, RN42 have HID. what is the function of HID? thanks

[zoeyan]

Hi Sir,  I am just curious that is it possible for the raspberry pi talk to arduino concurrently by adding more code in the file in your video? If so, can you give me some hints of how to achieve that?

[danieladiaz]

I have a question. Why do you connect the arduino to the Pi if you are sending tha data via bluetooth? Is it necessary ?. And I have another question the bluetooth module is configured as a Master or as a Slave?

[mukeshbadigineni]

i couldn't find the code in description please get me
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[amanmishra]

Hello sir, can i use the same code for HC-05 module

[gabenfanboy]

why cant anyone simply show how to connect arduino to rpi with bluetooth? i just want to send a simple message, not led/ghiny or even more shit