pylgbst: Cannot run a Lego tram

I’m trying to create a working solution for the new Lego Christmas tram. We want to make it run periodically in a shop window.

My plan is to use a Raspberry Pi connecting using Bluetooth, and then write some software to run the tram every now and then. As a start: My family wants me to setup an SMS gateway, so visitors outside the window can start the tram on demand by sending a text message. 😃

But first things first: I need a Python library to control the tram - and I would like to use pylgbst. But unfortunately, I cannot make it work.

Before diving into the details, I want to add that it actually works with another Python library known as BrickNil. However, this library has its own set of challenges, and it seems to be completely unsupported - there hasn’t been an update in three years, and PR and issues are unanswered. So I would prefer helping out to make pylgbst work.

Hardware for the tram is determined by Lego: An 88009 SmartHub, an 88011 Train Motor, and an 88005 Light Set.

BrickNil uses Bleak, and I can write a program and connect to the hub, change the colour of the builtin LED, and turn on the light in the external light set.

However, when I try pylgbst on the same RPi and tram, nothing works. If I try using pylgbst with bluepy, it can find the hub, but reports that nothing is connected. If I try using Bleak, it cannot find anything at all.

In issue #124 I found a small debug program. If I modify this to use a specific BT backend, I get these results for bluepy:

lars@lego-sporvogn:~ $ sudo ./test.py 
DEBUG:comms-bluepy:Trying to connect client to MoveHub with MAC: 90:84:2b:c6:9a:f8
INFO:comms-bluepy:Discovering devices...
DEBUG:comms:Checking device: None, MAC: xx:xx:xx:xx:xx:xx
DEBUG:comms:Checking device: Smart Hub, MAC: 90:84:2b:c6:9a:f8
INFO:comms:Found Smart Hub at 90:84:2b:c6:9a:f8
DEBUG:comms-bluepy:Writing to handle 15: b'0100'
lars@lego-sporvogn:~ $ 

and for Bleak:

lars@lego-sporvogn:~ $ ./test.py 
DEBUG:asyncio:Using selector: EpollSelector
DEBUG:asyncio:Using selector: EpollSelector
INFO:comms-bleak:Discovering devices... Press green button on Hub
lars@lego-sporvogn:~ $ 

Nothing more before the test program times out.

The RPi runs the latest Raspbian as of writing and updated to the latest and greatest everything. This means Python version 3.9.2.

I would love to see this work - but we’re in a bit of a hurry, our traditional Christmas exhibition in the shop window opens Dec. 1st. 😃