chumicro-timing 0.1.21

Wraparound-safe millisecond tick helpers and heartbeat scheduling for CircuitPython, MicroPython, and CPython.

chumicro-timing

Non-blocking timers that handle millisecond wraparound for you.

Capture ticks_ms() once per loop, hand it to a Heartbeat, and you've got clean periodic timing — no time.sleep(), no wraparound bugs. Works on CircuitPython, MicroPython, and CPython.

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

Installation

CircuitPython (circup)

circup is CircuitPython's package manager — it uses bundles to find third-party packages. Register the ChuMicro bundle once, then install by name:

circup bundle-add ChuMicro/ChuMicro-Bundle
circup install chumicro-timing

MicroPython (mip)

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

CPython (pip)

pip install chumicro-timing

Experimental (pre-release) versions and channel switching

Pre-release builds are published automatically when a library version is bumped. Do not register both bundles simultaneously — circup may pick either version for a given package.

# CircuitPython — switch to experimental
circup bundle-remove ChuMicro/ChuMicro-Bundle              # skip if never added
circup bundle-add ChuMicro/ChuMicro-Bundle-Experimental
circup install chumicro-timing

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

# CPython
pip install chumicro-timing-experimental

Quick example

from chumicro_timing import Heartbeat, ticks_ms

heartbeat = Heartbeat(period_ms=1000)

while True:
    now = ticks_ms()
    if heartbeat.poll(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)

Heartbeat

Symbol	Description
Heartbeat(period_ms, ticks=None)	Periodic timer that fires once per elapsed period
Heartbeat.poll(now_ms)	Returns True once per period and advances the timer
Heartbeat.is_due(now_ms)	Check whether the period has elapsed (without advancing)
Heartbeat.reset(now_ms)	Restart the timer from the given timestamp
Heartbeat.period_ms	The configured period (read-only property)

Testing

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

Related libraries

For structured task scheduling with multiple services, see runner. Runner is built on timing — it captures ticks_ms() once per tick and dispatches services on a shared timestamp.

Platform support

You don't need to pick a tick source — the library detects your runtime and uses the best one available:

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

All sources are masked to a 2²⁹ ms period, so behavior is identical regardless of which source is used.

Testing your code

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

from chumicro_timing import Heartbeat
from chumicro_timing.testing import FakeTicks

fake = FakeTicks()
heartbeat = Heartbeat(period_ms=100, ticks=fake)

now = fake.ticks_ms()
assert heartbeat.poll(now) is False

fake.advance(100)
now = fake.ticks_ms()
assert heartbeat.poll(now) is True

Examples

Example	What it shows
heartbeat_blink.py	Basic periodic timer loop
multiple_heartbeats.py	Multiple heartbeats at different rates
timeout_check.py	One-shot timeout using is_due
debounce.py	Simulated button debounce
periodic_tick.py	Manual periodic loop (what Heartbeat does under the hood)
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

Docs

📖 Stable docs · Experimental docs

Find this library

• PyPI: chumicro-timing
• Bundle: ChuMicro-Bundle (CircuitPython & MicroPython)
• Experimental bundle: ChuMicro-Bundle-Experimental
• Source: libraries/timing