Thymio, Python et Asebamedulla
, par
Le robot Thymio-II est un robot très facile à utiliser en enseignement de l’informatique. Grâce aux développeurs de Aseba, il est même possible de le contrôler en Python à partir d’une machine GNU/Linux, via D-Bus et l’outil en ligne de commande Asebamedulla. Mais la documentation est pour le moment très succincte au sujet de la gestion des événements. Voici en 50 lignes une démo simple pour qui voudrait s’éviter quelques longues heures de débuggage avec D-Bus.
- #!/usr/bin/python
- # -*- coding: utf-8 -*-
- import dbus
- import dbus.mainloop.glib
- import tempfile
- thymio = "thymio-II"
- # first we need the network access to Thymio through DBus
- dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
- bus = dbus.SessionBus() # we use session bus (alternative: system bus)
- network = dbus.Interface(bus.get_object('ch.epfl.mobots.Aseba', '/'),
- dbus_interface='ch.epfl.mobots.AsebaNetwork')
- """
- Event listening
- the Thymio has to run a code forwarding interesting local events.
- Lets write our own aesl source file for that purpose.
- """
- with tempfile.NamedTemporaryFile(suffix='.aesl', delete=False) as aesl:
- aesl.write('<!DOCTYPE aesl-source>\n<network>\n')
- #declare global events and ...
- aesl.write('<event size="0" name="fwd.button.backward"/>\n')
- aesl.write('<event size="0" name="become.yellow"/>\n')
- aesl.write('<event size="0" name="fwd.timer0"/>\n')
- aesl.write('<node nodeId="1" name="'+thymio+'">\n')
- #...forward some local events as outgoing global ones
- aesl.write('onevent button.backward\n emit fwd.button.backward\n')
- aesl.write('onevent timer0\n emit fwd.timer0\n')
- # add code to handle incoming events
- aesl.write('onevent become.yellow\n call leds.top(31,31,0)\n')
- aesl.write('</node>\n')
- aesl.write('</network>\n')
- #load the aesl code into Thymio
- network.LoadScripts(aesl.name)
- print "%s loaded into Thymio"% aesl.name
- #Create an event filter and catch events
- eventfilter = network.CreateEventFilter()
- events = dbus.Interface(
- bus.get_object('ch.epfl.mobots.Aseba', eventfilter),
- dbus_interface='ch.epfl.mobots.EventFilter')
- # pushing or releasing the backward button will turn Thymio into yellow
- def evt_callback(*args):
- if args[1] == "fwd.button.backward":
- print "** backward button pressed or released **"
- network.SendEventName('become.yellow', [])
- elif args[1] == "fwd.timer0":
- print 'tick'
- else:
- print [args]
- network.SetVariable(thymio, "timer.period", [1000,0])
- events.ListenEventName('fwd.timer0') # not required for the first event in aesl file!
- events.ListenEventName('fwd.button.backward')
- events.connect_to_signal('Event', evt_callback)
- # Run an event loop
- import gobject
- loop = gobject.MainLoop()
- loop.run()
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