CODEWITHSUNDEEP
pythonlinuxbluetoothraspberry-piraspberry-pi3
Oliver Kucharzewski
Oliver Kucharzewski

Reputation: 2655

Running functions on bluetooth pair request

I've recently been learning electric circuitry using arduino and am looking to implement some changes to my Raspberry Pi application.

I used this outdated tutorial a few years ago to create my pi bluetooth receiver which is working well at the moment (https://www.instructables.com/id/Turn-your-Raspberry-Pi-into-a-Portable-Bluetooth-A/) but one downfall of this out-dated tutorial is that bluetooth connections have to be accepted via the screen (which is off because bluetooth speakers do not have screens).

My plan: use a button to accept bluetooth connections and use a flashing green LED to indicate a connection request.

How can I create a script that 'listens' for bluetooth pairing requests and run python code accordingly when its listening? With this, how can I connect to the bluetooth to accept a pair request?

I'm not too familiar with Raspberry Pi script placement, but am familiar with Python and know how I can connect to GPIO.

Thanks :)

Upvotes: 0

Views: 1847

Answers (2)

Lubo
Lubo

Reputation: 384

What you are searching for is called a Bluetooth Agent. You need to use an official linux bluetooth protocol stack BlueZ. There is documentation describing the Agent API link. It uses DBus for communication. You need to invoke the following steps:

  1. Create a bluetooth agent written in python and publish it at certain DBus object path. Your agent must implement org.bluez.Agent1 interface as described in Agent API doc.
  2. Then you need to register this agent by calling RegisterAgent method from Agent API. Here you will provide the DBus path where your agent is located and also you will provide the capability in your case "DisplayYesNo" (LED as a display for pairing request, and button with some timeout for implementing Yes/No).

  3. Also register your agent as a default agent by calling RequestDefaultAgent

  4. Now if you try to pair with your device the appropriate function in your agent will be called (I think for your use case it will be RequestAuthorization) If you want to accept the pairing you will just return from this function, if you want to reject the pairing you must throw a DBus error inside this function.

As a starting point for you I would suggest you to look at this simple python Agent: https://github.com/pauloborges/bluez/blob/master/test/simple-agent It implements all the functionality you need so just update it according to your needs.

Have fun :)

Upvotes: 1

Alex W
Alex W

Reputation: 38253

Have you tried using this Python library ? It lists Raspberry Pi support

Additionally, here's some info on listening for incoming Bluetooth connections:

Bluetooth programming in Python follows the socket programming model. This is a concept that should be familiar to almost all network programmers, and makes the transition from Internet programming to Bluetooth programming much simpler. Example 3-2 and Example 3-3 show how to establish a connection using an RFCOMM socket, transfer some data, and disconnect.

import bluetooth

server_sock=bluetooth.BluetoothSocket( bluetooth.RFCOMM )

port = 1
server_sock.bind(("",port))
server_sock.listen(1)

client_sock,address = server_sock.accept()
print "Accepted connection from ",address

data = client_sock.recv(1024)
print "received [%s]" % data

client_sock.close()
server_sock.close()

An RFCOMM BluetoothSocket used to accept incoming connections must be attached to operating system resources with the bind method. bind takes in a tuple specifying the address of the local Bluetooth adapter to use and a port number to listen on. Usually, there is only one local Bluetooth adapter or it doesn't matter which one to use, so the empty string indicates that any local Bluetooth adapter is acceptable. Once a socket is bound, a call to listen puts the socket into listening mode and it is then ready to accept incoming connections.

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Source

Upvotes: 0

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