Why doesn't Timer() have .start()?

[PsuFan]

Why can't I initialize my period, mode, and callback parameters and then start() and stop() it when needed?

[sosi-deadeye]

You could make your own class to get this functionality. Adding functions/methods increases the firmware size.

The timer is started with the init method.

import time

from machine import Timer


class OneShotTimer:
    def __init__(self, id, delay, callback):
        self.timer = Timer(id)
        self.delay = delay
        self.callback = callback

    def start(self):
        self.timer.init(mode=Timer.ONE_SHOT, period=self.delay, callback=self.callback)

    def stop(self):
        self.timer.deinit()


class Callback:
    def __init__(self):
        self.count = 0

    def __call__(self, timer: Timer):
        self.count += 1
        print(f"Callabck {self.count}")


my_timer = OneShotTimer(1, 1000, Callback())
my_timer.start()

You could test it here: https://wokwi.com

[PsuFan]

Pretty good but what if you start it twice before the first one is complete? But yeah I guess its pretty trivial at this point but still something I think would be nice to have.

[sosi-deadeye]

Pretty good but what if you start it twice before the first one is complete?
I don't know yet. Maybe the timer is restarted. You could prevent to start it, when the timer is still running. Just a little change.

I haven't tested it, but it should work.

import time

from machine import Timer


class OneShotTimer:
    def __init__(self, id, delay, callback):
        self.timer = Timer(id)
        self.delay = delay
        self.callback = callback
        self.active = False

    def _callback(self, timer: Timer):
        """
        Helper method to set self.active to False, after the callback has been called with the timer as argument
        """
        self.callback(timer)
        self.active = False

    def start(self):
        if not self.active:
            self.active = True
            self.timer.init(mode=Timer.ONE_SHOT, period=self.delay, callback=self._callback)

    def stop(self):
        self.timer.deinit()
        self.active = False


class Callback:
    def __init__(self):
        self.count = 0

    def __call__(self, timer: Timer):
        self.count += 1
        print(f"Callabck {self.count}")


my_timer = OneShotTimer(1, 1000, Callback())
my_timer.start()