Hello, Over the last couple of years I’ve been doing some work with accessing BlueZ from the Python programming language. More recently I’ve been trying to create a library to lower the barrier to getting started with Bluetooth on Linux. On that library we have recently done a retrospective of where we are. (TL;DR https://github.com/ukBaz/python-bluezero/issues/126) The discussion spilled over to twitter where there was a suggestion that some of our concerns should be shared back to the BlueZ project. https://twitter.com/sandeepmistry/status/891836962952314880 I am not sure how relevant our feedback is to the broader user base of the BlueZ project. However, it is true that we can’t complain that our needs aren’t being addressed by BlueZ if we don’t give feedback. I also accept that part of the issue here is with me as I don’t come from a background where I know about the low level details of Bluetooth and the C language. I am coming at this from the direction of learning enough to rapidly prototype Python applications that contain some Bluetooth functionality. Context: In my volunteering role as a STEM ambassador I have been a mentor on a few school projects for engineering challenges where Bluetooth functionality would have been helpful. These school projects typically use hardware like Raspberry Pi’s, BBC micro:bits and tablets/phones where Bluetooth hardware is readily available. My goal is to be able to create workshops that can be run at schools, STEM fairs and community maker events that help people get started exploring what is possible with Bluetooth and Python. Building From Source: My first bit of feedback is that things with BlueZ are a lot better now than they were a few short years ago. However this is the first challenge as it takes a long time for updates to appear in operating systems. The default Raspberry Pi OS is still shipping with BlueZ 5.23 which isn’t much use for BLE. Even when Raspbian moves to being a Debian Stretch based release, it will be BlueZ 5.43. This means that much of the DBus API will be behind the experimental flag and will be missing some of the great recent updates such as AcquireWrite, AcquireNotify and set name in scan response. While building from source is something I’ve become comfortable with, getting organisers of workshop machines and users to do this is often too large a barrier to entry. Python DBus Library: As I’ve written about before on this list, there is not an obvious choice when it comes to a Python DBus library. I think the BlueZ ‘test’ Python examples use the dbus-python library. There seems to be concerns about this Python library. Pydbus seems to be a recommended library although there seems to be several holes in it for use with BlueZ. The owner of the library appears to have moved on to another project so updates (or merging of pull requests) seems to be sporadic. Beacons: Again another topic that has been discussed on this mailing list before. There seems to have been a number of people that want to have a Linux SBC continuously passively scan for beacons. This is something that is not supported by the BlueZ DBus API. I believe the concern is with flooding the bus. Could something similar to AcquireNotify be done to solve this? Testing: It would be good to be able to test the Python apps without real hardware. It would be good if BlueZ could provide some way of mock/fake/stub so that unit testing could be easily done. The library python-dbusmock showed some promise however the bluez5.py template needs some work. Our New Direction - Python Only Solution: Because of the issues raised above, investigation has started on using only Python standard libraries to find a solution for our library. This will allow our library to move faster than OS updates allow as it will be easy to install directly from PyPI with fewer dependencies. The current investigation is looking to by-pass bluetoothd by using HCI. What we have so far can be seen at: https://github.com/TheBubbleworks/python-hcipy Regards, Barry -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
