My problem is that I get:
raise ValueError ("invalid protocol")
ValueError: invalid protocol
from this line of code:
sock=bluetooth.BluetoothSocket(bluetooth.RFCOMM)
I don't understand why I'm getting this error.
The reason I'm using this is because I want to send a keyboard event to a device that is connected via Bluetooth.
Your question tag "l2cap" is inconsistent with your code snippet that refers to RFCOMM. In my experience, on Windows7, sock=bluetooth.BluetoothSocket(bluetooth.RFCOMM) does not raise an error however sock=bluetooth.BluetoothSocket(bluetooth.L2CAP) does raise an error. Now if you really did want RFCOMM, it could be a hardware issue. For example, if your Bluetooth resides on USB Bluetooth dongle, then the software should raise this error when the dongle is unplugged. The rest of my answer mostly assumes that you were trying to get L2CAP.
Generally the error is raised because that protocol is not supported by your driver. Specifically I have found that L2CAP is not accessible in PyBluez in Python2 or Python3 on Windows 7. In Python3 on Linux L2CAP is accessible from "import socket".
It is unclear to me whether the PyBluez limitation is present in both the Widcomm and MSBT stacks on Win7. Also it is unclear to me whether more PyBluez work could fix the issue if the service is truly unavailable in the driver that PyBluez is trying to wrap.
Hope that helps.
