Timers

Timers#

Timers are Streams as well, they behave similarly to subscriptions.

To create a timer you use node->icey().create_timer(<period-time>, <callback>, <is_one_off_timer>):

icey::TimerStream my_timer = node->icey().create_timer(100ms);

Key differences to regular ROS are:#

  • create_timer returns a Stream (you can access the rclcpp::TimerBase using stream.timer)

  • Asynchronous functions, i.e. coroutines, can be used as callbacks

  • The lifetime of the timer is bound to the lifetime of the node: This means, you don’t need to store the timer as a member field inside the node class, i.e. you do not have to do bookkeeping

We can easily register a callback and use the timer like you usually would:

auto my_timer = node->icey().create_timer(100ms);

my_timer.then([](size_t ticks) {
    /// Do work
});

The ticks value in the callback indicates the number of times this timer ticked (starting from zero at the first call).

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