Connection Guide

Connections are another core part of ABle, here will will introduce some examples on how to use ABle to handle BLE connections. We modeled the API after the Berkeley Socket API, so if you have worked with sockets this should be familiar.

Tip

We highly suggest looking at the getting started doc and the advertising guide before looking at this guide as you need to be setup and advertising before you can connect.

Simple Connections

Using the stencil provided by the getting started guide, we can now accept connections after calling listen() on the peripheral. This will block on the accept() call until a central connects wait five seconds, then disconnect the central.

# Start the peripheral server
await able_peripheral.listen()

while True:
    # Block here until a connection
    new_central = await able_peripheral.accept()
    print(f"New connection from {new_central}")

    # Wait 5 seconds then disconnect
    await asyncio.sleep(5)
    await new_central.close()

Tip

See the development doc (todo Bernie) for useful tools for testing this by leveraging your phone to scan for the peripheral and connect to it.

Clientside Disconnecting

Notice that the above demonstrates how a server (the peripheral) would disconnect using the close() method. If a central/client initiates the disconnect, any IO operation to that central will raise an exception and calling central.close() will log a warning and do nothing if the central already disconnected.

(Dis)connect Callbacks

It is easy to define callbacks to fire whenever a central connects or disconnects with Able. Simply before calling listen() we can bind a callback function, let’s define some callback functions.

def connect_callback(callback_data):
    print("Connected to a central yippee!")

def disconnect_callback(callback_data):
    print("Disconnected from a central :(")

These functions will be passed an instance of DeviceCallbackData which can be used to get information regarding which central connected or disconnected. We can now add these callback functions to the peripheral.

# Add user defined callbacks
able_peripheral.add_connect_callback(connect_callback)
able_peripheral.add_disconnect_callback(disconnect_callback)

Now whenever a central connects or disconnects those callbacks will be called.