Subscribe to the Create® 3 interface buttons
Our next step is to subscribe to the Create® 3 interface buttons topic to receive button presses.
We will need to create a rclpy.Subscription as well as a callback function for the subscription.
The callback function will be called every time we receive a message on the interface buttons
topic.
class TurtleBot4FirstNode(Node):
lights_on_ = False
def __init__(self):
super().__init__('turtlebot4_first_python_node')
# Subscribe to the /interface_buttons topic
self.interface_buttons_subscriber = self.create_subscription(
InterfaceButtons,
'/interface_buttons',
self.interface_buttons_callback,
qos_profile_sensor_data)
# Interface buttons subscription callback
def interface_buttons_callback(self, create3_buttons_msg: InterfaceButtons):
Notice that the interface_buttons_subscriber uses the InterfaceButtons message type, and the
quality of service is qos_profile_sensor_data. These parameters must match the topic,
otherwise the subscription will fail. If you are unsure what message type or QoS a topic is using,
you can use the ROS2 CLI to find this information.
Call ros2 topic info /<topic> --verbose to get the full details.
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