class Timer – control internal timers


Contrary with the rest of the API, timer IDs start at 1, not a t zero. This is because the Timer API is still provisional. A new MicroPython wide API will come soon.

Timers can be used for a great variety of tasks, calling a function periodically, counting events, and generating a PWM signal are among the most common use cases. Each timer consists of 2 16-bit channels and this channels can be tied together to form 1 32-bit timer. The operating mode needs to be configured per timer, but then the period (or the frequency) can be independently configured on each channel. By using the callback method, the timer event can call a Python function.

Example usage to toggle an LED at a fixed frequency:

from machine import Timer
tim = Timer(4)                                   # create a timer object using timer 4
tim.init(mode=Timer.PERIODIC)                    # initialize it in periodic mode
tim_ch =, freq=2)            # configure channel A at a frequency of 2Hz
tim_ch.callback(handler=lambda t:led.toggle())   # toggle a LED on every cycle of the timer

Example using named function for the callback:

from machine import Timer
tim = Timer(1, mode=Timer.PERIODIC)
tim_a =, freq=1000)

led = Pin('GPIO2', mode=Pin.OUT)

def tick(timer):                # we will receive the timer object when being called
    print(timer.time())         # show current timer's time value (is microseconds)
    led.toggle()                # toggle the LED


Further examples:

from machine import Timer
tim1 = Timer(2, mode=Timer.EVENT_COUNT)                         # initialize it capture mode
tim2 = Timer(1, mode=Timer.PWM)                                 # initialize it in PWM mode
tim_ch =, freq=1, polarity=Timer.POSITIVE) # start the event counter with a frequency of 1Hz and triggered by positive edges
tim_ch =, freq=10000, duty_cycle=50)       # start the PWM on channel B with a 50% duty cycle
tim_ch.time()                                                   # get the current time in usec (can also be set)
tim_ch.freq(20)                                                 # set the frequency (can also get)
tim_ch.duty_cycle(30)                                           # set the duty cycle to 30% (can also get)
tim_ch.duty_cycle(30, Timer.NEGATIVE)                           # set the duty cycle to 30% and change the polarity to negative
tim_ch.event_count()                                            # get the number of captured events
tim_ch.event_time()                                             # get the the time of the last captured event
tim_ch.period(2000000)                                          # change the period to 2 seconds


Memory can’t be allocated inside irq handlers (an interrupt) and so exceptions raised within a handler don’t give much information. See micropython.alloc_emergency_exception_buf() for how to get around this limitation.


class machine.Timer(id, ...)

Construct a new timer object of the given id. If additional arguments are given, then the timer is initialised by init(...). id can be 1 to 4.


timer.init(mode, *, width=16)

Initialise the timer. Example:

tim.init(Timer.PERIODIC)             # periodic 16-bit timer
tim.init(Timer.ONE_SHOT, width=32)   # one shot 32-bit timer

Keyword arguments:

  • mode can be one of:
    • Timer.ONE_SHOT - The timer runs once until the configured period of the channel expires.
    • Timer.PERIODIC - The timer runs periodically at the configured frequency of the channel.
    • Timer.EDGE_TIME - Meaure the time pin level changes.
    • Timer.EDGE_COUNT - Count the number of pin level changes.
  • width must be either 16 or 32 (bits). For really low frequencies <= ~1Hz (or large periods), 32-bit timers should be used. 32-bit mode is only available for ONE_SHOT AND PERIODIC modes.

Deinitialises the timer. Disables all channels and associated IRQs. Stops the timer, and disables the timer peripheral., **, freq, period, polarity=Timer.POSITIVE, duty_cycle=0)

If only a channel identifier passed, then a previously initialized channel object is returned (or None if there is no previous channel).

Othwerwise, a TimerChannel object is initialized and returned.

The operating mode is is the one configured to the Timer object that was used to create the channel.

  • channel if the width of the timer is 16-bit, then must be either TIMER.A, TIMER.B. If the width is 32-bit then it must be TIMER.A | TIMER.B.

Keyword only arguments:

  • freq sets the frequency in Hz.
  • period sets the period in microseconds.


Either freq or period must be given, never both.

  • polarity this is applicable for:
    • PWM, defines the polarity of the duty cycle
    • EDGE_TIME and EDGE_COUNT, defines the polarity of the pin level change to detect. To detect both rising and falling edges, make polarity=Timer.POSITIVE | Timer.NEGATIVE.
  • duty_cycle only applicable to PWM. It’s a percentage (0-100)

class TimerChannel — setup a channel for a timer

Timer channels are used to generate/capture a signal using a timer.

TimerChannel objects are created using the method.


timerchannel.irq(*, trigger, priority=1, handler=None)

The behavior of this callback is heaviliy dependent on the operating mode of the timer channel:

  • If mode is Timer.PERIODIC the callback is executed periodically with the configured frequency or period.
  • If mode is Timer.ONE_SHOT the callback is executed once when the configured timer expires.
  • If mode is Timer.PWM the callback is executed when reaching the duty cycle value.

The accepted params are:

  • priority level of the interrupt. Can take values in the range 1-7. Higher values represent higher priorities.
  • handler is an optional function to be called when the interrupt is triggered.

Returns a callback object.


Get or set the timer channel frequency (in Hz).


Get or set the timer channel period (in microseconds).


Get or set the timer channel current time value (in microseconds).


Get the number of edge events counted.


Get the time of ocurrance of the last event.


Get or set the duty cycle of the PWM signal (in the range of 0-100).