Honch MicroPython SDK

Stable MicroPython wrapper for the canonical Honch C core. The Python package keeps a small honch.Honch API while behavior comes from the same shared sources used by the ESP-IDF and POSIX ports.

Status

Stable 0.3.1. The SDK is not standalone pure Python; firmware must be built with the _honch_core user C module.

This port targets MicroPython. CircuitPython is not covered by the current user C module build flow.

Build Into MicroPython

From a MicroPython checkout, build a port with the Honch user module:

make -C ports/unix \
  USER_C_MODULES=/path/to/SDK/ports/micropython/usermod/honch/micropython.cmake

For board firmware, pass the same user module path and freeze the wrapper:

make BOARD=MYBOARD \
  USER_C_MODULES=/path/to/SDK/ports/micropython/usermod/honch/micropython.cmake \
  FROZEN_MANIFEST=/path/to/SDK/ports/micropython/manifest.py

The Honch user C module does not set firmware-global MicroPython options such as MICROPY_C_HEAP_SIZE. Keep heap sizing in the board or host firmware configuration. If your board needs additional C heap for Honch and other native modules, opt into that value in the board config rather than in the user module.

mip can install wrapper files from package metadata, but those files require firmware that already contains _honch_core. Do not install the honch/ wrapper into /lib when it is already frozen into the firmware. Keeping both copies wastes the board filesystem and can make MicroPython import an older /lib/honch package instead of the frozen SDK.

Basic Usage

import honch

client = honch.Honch(
    api_key="project-key",
    endpoint_url="https://i.honch.io",
    device_id="device-serial-001",
    device_model="ActionCam X1",
    firmware_version="1.2.3",
    event_buffer=bytearray(8192),
)

client.identify("user-123", {"plan": "beta"})
client.session_start("recording")
client.track("recording_started", {"mode": "hdr"})
client.session_end()
client.flush()
client.shutdown()

Configuration

Required:

• api_key
• device_id
• device_model
• firmware_version
• event_buffer

Optional:

• endpoint_url (default https://i.honch.io)
• environment
• batch_size
• max_queued_events
• max_event_bytes
• transport_timeout_ms (finite positive milliseconds, clamped to 10000)
• flush_interval_seconds
• flush_min_interval_ms (default 15000; use 0xFFFFFFFF to disable for benchmarks)
• flush_event_threshold
• flush_retry_initial_ms
• flush_retry_max_ms
• battery_low_threshold
• connectivity_callback (return false while offline; ticks are skipped and flush() raises OfflineError)

Python platform=, transport=, battery_callback=, and auto_properties_callback= hooks are not supported by the C-core-derived port. Board behavior belongs in the user module adapters.

client init does synchronous work on the caller's thread. It validates config, initializes the C core against the caller-provided event buffer, derives initial state from the supplied device/config values, and queues $device_boot before returning. It does not perform network I/O; delivery remains cooperative through tick() or explicit flush() calls.

Crash reporting is automatic. client.install_error_hook() installs a best-effort sys.excepthook wrapper (on runtimes that expose that hook) that emits a one-time $crash event for an uncaught exception (source="exception", with the exception type in exception_cause); the original exception is always delivered to the previous hook. client.report_log_error(message, component=...) emits a bounded, coalesced $error event and is intended to be driven automatically (e.g. from a logging.Handler), not sprinkled through application code. The port does not install panic hooks or board-specific reset-reason adapters; board reset telemetry belongs in the user module adapter.

client.tick() and client.flush() may block for up to the configured transport timeout because urequests.post holds the MicroPython interpreter while the HTTP request is in progress. Do not call tick() from a latency-sensitive control loop, timing-critical sensor loop, UI refresh path, or watchdog-sensitive section. Do not call tick() or flush() from ISR-adjacent callbacks or high-priority tasks. Schedule it from a low-priority part of the program where a stalled interpreter is acceptable for the configured timeout. Explicit timeout values above the hard maximum of 10000 ms are clamped. Each scheduled tick posts at most one wire chunk, so large queued uploads may need several pump iterations to finish.

Do not call tick() while WLAN is disconnected or the radio is intentionally off. If your loop cannot guarantee that, pass connectivity_callback; it should be fast and read host-owned connectivity state.

Public API

client.track(event_name, properties=None)
client.report_log_error(message, component=None)
client.install_error_hook()
client.uninstall_error_hook()
client.identify(distinct_id, traits=None)
client.set_property(key, value=None)
client.session_start(session_name=None)
client.session_end()
client.connectivity_changed(connected)
client.connected()
client.disconnected()
client.tick()
client.flush()
client.reset()
client.shutdown()
client.get_device_id()
client.queue_stats()

After identify(), future events use the new distinct ID. The $identify event also includes the previous identity as $anon_distinct_id, usually the device ID, so earlier anonymous events can merge into the identified person.

Call client.tick() periodically from the device main loop for scheduled flush work. Use client.flush() when you want an immediate drain attempt.

Properties support typed event values, including strings, integers, floats, booleans, lists, dictionaries, null, and bytes. Capture may reject bytes unless the project enables binary properties. SDK-owned auto property keys supplied by users are rejected before compact wire-v2 packetization.

Storage And Transport

The default user C module stores queued events in the caller-provided event_buffer. Events, identify() state, and firmware-version state are volatile by default and are lost across reset or power loss. device_id is required because this port does not persist SDK identity. Pass a caller-provided stable device_id from board provisioning, NVS, a filesystem file, or another product-owned durable source.

That RAM queue is bounded and compact. Consuming a non-tail event uses an O(n) memmove per consumed event to keep the caller-provided buffer contiguous; this is acceptable at default sizes, but larger buffers and queue limits should be measured on the target board.

Flush sends compact chunk frames to POST <endpoint_url>/capture with Content-Type: application/vnd.honch.chunk, X-Honch-Project-Key, and X-Honch-Stream-Id.

Security

Use HTTPS in production. Verify the board has network, time, and trust setup needed for certificate validation. Keep project keys out of source control, logs, and event properties.

Tests

PYTHONDONTWRITEBYTECODE=1 PYTHONPATH=ports/micropython python3 -m unittest discover \
  -s ports/micropython/tests -t . -v

Full runtime validation requires building MicroPython with _honch_core and running the wrapper on that interpreter or firmware.