Python library to interact with LEGO Move Hub
Best way to start is to look into demo.py file, and run it.
If you have Vernie assembled, you might look into and run scripts from vernie directory.
Features
- auto-detect and connect for Bluetooth device
- auto-detects devices connected to Hub
- angled and timed movement for motors
- LED color change
- motors: angled and timed movement, rotation sensor subscription
- push button status subscription
- tilt sensor subscription: 2 axis, 3 axis, bump detect modes
- color & distance sensor: several modes to measure distance, color and luminosity
- battery voltage subscription available
- permanent Bluetooth connection server for faster debugging
Usage
Install library like this:
pip install https://github.com/undera/pylgbst/archive/0.2.tar.gz
Then instantiate MoveHub object and start invoking its methods. Following is example to just print peripherals detected on Hub:
from pylgbst import MoveHub
hub = MoveHub()
for device in hub.devices:
print(device)
TODO: more usage instructions
General Information
connection params
hub's devices detect process & fields to access them
general subscription modes & granularity info
good practice is to unsubscribe, especially when used with DebugServer
Motors
Motor Rotation Sensors
Tilt Sensor
Color & Distance Sensor
Tip: laser pointer pointing to sensor makes it trigger distance sensor
LED
Push Button
Hub object has field button to subscribe to button press and release events. Note that Button class is not real Peripheral, we just mimic it. Subscribing to button uses internal mechanics which is slightly different from other peripherals.
Still, subscribing to button is done usual way:
from pylgbst import MoveHub
def callback(is_pressed):
print("Btn pressed: %s" % is_pressed)
hub = MoveHub()
hub.button.subscribe(callback)
Power Voltage & Battery
Hub object has field battery to subscribe to battery voltage status. Callback accepts single parameter with current value. The range of values is unknown, it's 2-byte integer. Every time data is received, value is also written into last_value field of Battery object.
from pylgbst import MoveHub
import time
def callback(value):
print("Voltage: %s" % value)
hub = MoveHub()
hub.battery.subscribe(callback)
time.sleep(1)
print ("Value: " % hub.battery.last_value)
TODO: investigate mode parameter for battery
Debug Server
Running debug server opens permanent BLE connection to Hub and listening on TCP port for communications. This avoids the need to re-start Hub all the time.
There is DebugServerConnection class that you can use with it, instead of BLEConnection.
Starting debug server is done like this:
sudo python -c "from pylgbst.comms import *; \
import logging; logging.basicConfig(level=logging.DEBUG); \
DebugServer(BLEConnection().connect()).start()"
TODO
- Give nice documentation examples, don't forget to mention logging
- document all API methods
- make sure unit tests cover all important code
- handle device detach and device attach events on ports C/D
- generalize getting device info + give constants (low priority)
- organize requesting and printing device info on startup - firmware version at least
- make debug server to re-establish BLE connection on loss
Links
- https://github.com/JorgePe/BOOSTreveng - source of protocol knowledge
- https://github.com/spezifisch/sphero-python/blob/master/BB8joyDrive.py - example with +-another approach to bluetooth libs
Some things around visual programming: