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chumicro-timing

Timers that don't block. Your loop keeps ticking.

Capture ticks_ms() once per loop pass, hand it to a Rate or a Deadline, and you've got clean drift-free timing on CircuitPython, MicroPython, or CPython. Tick-source detection is automatic, wraparound is handled, and there are no dependencies on anything else in ChuMicro. It's where every other library starts.


Part of the ChuMicro family: small, focused Python libraries for microcontrollers and laptops. Browse all libraries.

Install

# CircuitPython (after `circup bundle-add ChuMicro/ChuMicro-Bundle`)
circup install chumicro_timing

# MicroPython
mpremote mip install github:ChuMicro/ChuMicro-Bundle/chumicro_timing

# CPython
pip install chumicro-timing

For bundle setup, pre-compiled .mpy bundles, the experimental channel, and details on PyPI naming, see the chumicro INSTALL guide.

Quick example

from chumicro_timing import Rate, ticks_ms

rate = Rate(1000, ticks_ms())

while True:
    now = ticks_ms()
    if rate.due(now):
        print("one second elapsed")
    # ... do other work ...

What's included

Tick functions

Symbol Description
ticks_ms() Current time in milliseconds (keeps counting even when it wraps around)
ticks_diff(end, start) Time elapsed between two tick values (handles wraparound correctly)
ticks_add(ticks, delta) Add milliseconds to a tick value (handles wraparound correctly)

Value objects

Symbol Description
Deadline(period_ms, now_ms) A single armed timeout: expired(now) / remaining(now) / reset(now)
Rate(period_ms, now_ms) Drift-free periodic cadence; due(now) fires at most once per period

Wait vocabulary (chumicro_timing.waits)

Opt-in completion-wait vocabulary for generator flows. Import it explicitly.

Symbol Description
Signal() A completion flag: set(value) / clear() / ready(now), with is_set and value readable directly
wait_for(signal, deadline_ms=None) Generator suspension helper: yield from wait_for(signal)

Testing

Symbol Description
FakeTicks(start_ms=0) Deterministic tick source for host-side tests
FakeTicks.advance(amount_ms) Move the fake clock forward

Where this fits

Leaf: no upstream ChuMicro deps. Everything in ChuMicro that owns time depends on it: runner, sockets, ntp, requests, http_server, mqtt, websockets.

Platform support

You don't need to pick a tick source. The library picks the best one available on your runtime. Behavior is identical regardless of which source is used.

Source Runtime
supervisor.ticks_ms CircuitPython 7+
time.ticks_ms MicroPython, some CircuitPython builds
time.monotonic_ns CPython, some CircuitPython boards
time.monotonic Final fallback (float seconds → int ms)

The library tries them top-to-bottom and uses the first one your runtime supports.

Technical detail: tick wraparound

All sources are masked to a 2²⁹ ms period (~6.2 days). ticks_diff and ticks_add handle wraparound correctly, so your timers keep working even when the counter rolls over.

Testing your code

The chumicro_timing.testing module provides FakeTicks for deterministic host-side tests with no wall-clock waits:

from chumicro_timing import Rate
from chumicro_timing.testing import FakeTicks

fake = FakeTicks()
rate = Rate(100, fake.ticks_ms())

assert rate.due(fake.ticks_ms()) is False

fake.advance(100)
assert rate.due(fake.ticks_ms()) is True

Examples

Example What it shows
rate_blink.py Basic periodic Rate loop
multiple_rates.py Multiple Rate timers at different rates
timeout_check.py One-shot deadline check using ticks_diff
debounce.py Simulated button debounce
periodic_tick.py Manual periodic loop (the same logic Rate wraps internally)
phase_locked_tick.py Drift-free deadline carrier, same period across late loops
circuitpython_blink.py LED blink on CircuitPython hardware
circuitpython_debounce.py GPIO button debounce on CircuitPython
micropython_blink.py LED blink on MicroPython hardware
micropython_debounce.py GPIO button debounce on MicroPython

Contributing

Issues, bug reports, and pull requests are welcome, and so is "I ran it on this board and here's what happened", some of the most useful feedback a hardware project can get. Development happens in the ChuMicro repository, whose contributing guide covers setup and the test workflow.

Docs

📖 Stable docs · Experimental docs

Find this library

License

MIT

Metadata

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0.8.4

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