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HiveInside V0.1 — the first release 🐝

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@MacNite MacNite released this 12 Aug 10:09
· 23 commits to main since this release
v0.1
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Learn about vigilant mode.

HiveInside is a stand-alone, battery-powered in-hive environmental and
acoustic sensor. It sits inside the hive, measures climate, vibration and
sound, and broadcasts the result as a BLE beacon that a
HiveHub / HiveScale picks up with a passive
scan and forwards to the backend. No cabling into the hive, no pairing window,
no wake-sync schedule — and, from this release on, firmware updates over the
air.

This is the first tagged release. The firmware is feature-complete for its
intended job: all four sensor groups, the shared FFT band analysis, the
HiveHub-compatible beacon, a watchdog, a measured low-power deployment profile,
and MCUboot-based BLE OTA that has been fixed and verified on real hardware.

Why a separate device?

The frame-mounted accelerometer is, per the literature (Ramsey et al. 2020,
Sci. Rep.), the only reliable way to predict swarming up to ~30 days
ahead — microphones cannot capture the critical ~20 Hz vibrational
signature. HiveInside puts that accelerometer, plus acoustic FFT bands and
climate sensing, inside the hive on a tiny wireless board, avoiding the cabling
a wired sensor needs.

Hardware

Built on the Seeed XIAO nRF54LM20A Sense, which folds most of the discrete
sensors onto one module, plus one external climate sensor.

Function Part Interface
3-axis vibration (swarm prediction, ~20 Hz) LSM6DS3TR-C — on-board 6-axis IMU I²C
Acoustic FFT (piping, hum, stress) MSM261DGT006 — on-board PDM mic PDM
Temperature + humidity SHT40 (external, 0x44) I²C
Battery voltage + charge nPM1300 PMIC fuel gauge — on-board —

The accelerometer probe auto-detects the chip by WHO_AM_I, so an external
LIS3DH / LIS2DH12 breakout at 0x18/0x19 runs the same pipeline for bench
comparisons. A 3D-printable enclosure for the XIAO, the SHT40 and a 500 mAh LiPo
lives in enclosure/.

Features

Full in-hive measurement, every 5 minutes. Each cycle reads all four sensor
groups and reduces them to the ecosystem-shared FFT bands, so a value means
the same thing here as it does on a HiveScale:

  • Vibration (mg, gravity removed): swarm 8–30 Hz, fanning 30–100 Hz,
    activity 100–200 Hz — plus broadband RMS and peak.
  • Acoustics (dBFS): sub-bass 50–150 Hz, hum 150–300 Hz, piping
    300–550 Hz, stress 550–1500 Hz, high 1500–3000 Hz — plus RMS and peak.
  • Climate: temperature and relative humidity.
  • Battery: cell voltage and state of charge.

Each group carries its own validity flag, so a failed or missing sensor is
reported as absent rather than as a zero-filled reading the backend would
mistake for real data. A partial board still gives a useful readout.

BLE beacon transport — no connection required. The full measurement is a
29-byte manufacturer-data advertisement, repeated every second by the
Bluetooth controller and read out of the air by HiveHub's existing passive scan.
Format version 2 keeps every version-1 field at its original offset and appends
acceleration peak and microphone peak, so an older HiveHub decoder keeps working
unchanged while an updated one gains both peaks. A compact identity record
in the scan response reports board ID and firmware version to active scans, which
is what lets HiveHub display and version-gate each node.

Firmware-over-BLE (OTA) — implemented and working. HiveInside has no WiFi, so
HiveHub is the relay:

backend (signed .bin + CRC-32)  ──►  HiveHub  ──(BLE GATT)──►  HiveInside
        firmware_releases              (WiFi)     OTA service    (dual slots)
  • MCUboot dual-slot with test-swap and automatic rollback.
  • Three GATT characteristics (control / data / status) — the only GATT
    attributes the device exposes; the measurement is never read over a
    connection.
  • Nothing is buffered on either side. HiveHub streams the HTTPS download
    straight through; HiveInside writes each chunk directly into its inactive
    slot. Nothing is committed until size and CRC-32 verify, so a dropped or
    corrupted transfer always leaves the node on its old image.
  • A transfer that stalls mid-stream is abandoned instead of hanging.
  • The STATUS characteristic reports state, bytes received, error and the
    failing operation's errno     — the whole field diagnosis for a sealed node
    with no console.

The one hardware-level blocker found during bring-up is fixed: on the nRF54,
RRAM writes run inside a radio timeslot, and at the driver default every OTA
died at exactly 488 bytes on the first real flash write. The write buffer is now
raised to a full 512-byte line flush per timeslot (with CONFIG_IMG_BLOCK_BUF_SIZE
pinned to match), and advertising restarts from a work item so a node comes back
after every OTA attempt instead of going dark until the next cycle.
See docs/ota-over-ble.md.

Ultra-low power, audited. The node idles with only the ~1 s advertiser
running; there is no deep-sleep rendezvous machinery to keep in sync. The whole
sensor island — IMU and microphone — is switched off between measurements at
both the nPM1300 LDO1 and the upstream power_en gate, and the firmware
explicitly releases Zephyr's boot-time regulator reference so the disable
actually reaches hardware instead of merely reporting success. PDM is stopped
after capture, the accelerometer is powered down, the SHT40 uses its
lowest-power single-shot command, and CONFIG_TICKLESS_KERNEL keeps the CPU off
between events. A separate lowpower deployment profile drops the UART,
console printk() and the measurement LED, and removes the regulator-boot-on
defaults so nothing is held powered from reset. BLE measurement advertising and
OTA are unchanged in that profile.
See docs/low-power.md.

Watchdog. A sealed node has nobody watching it, and a hang inside a driver —
a stuck I²C transfer, a dmic_read() that never returns — would otherwise leave
the firmware alive enough to keep advertising the last good measurement
forever, which from HiveHub looks like a hive that simply stopped changing. A
hardware watchdog catches that and resets the node.

One build system, reproducible. Zephyr with west --sysbuild is the only
supported build path — it builds MCUboot and the signed application together,
which is what makes both a bootable device and an OTA payload. A pinned
west.yml makes the workspace reproducible, and every build also drops a
version-stamped, variant-stamped copy of the signed image beside
zephyr.signed.bin:

hiveinside-nrf54lm20a-v0.4.7-bringup.signed.bin     # console on
hiveinside-nrf54lm20a-v0.4.7-lowpower.signed.bin    # deployment profile

The version comes from the same constants the node advertises, so the artifact
name and the on-air version can never drift apart — and the HiveHub dashboard
reads that name to fill in target and version by itself. CI builds both
configurations on every change.

Home Assistant. Through HiveHub's MQTT bridge, a HiveInside node appears as
its own Home Assistant device with exactly the entities it reports — climate,
cell voltage, firmware version, and its vibration and acoustic bands.
See docs/homeassistant.md.

Component versions in this release

Component Version Notes
HiveInside firmware 0.4.7 firmware-nrf54lm20a/, Zephyr + west --sysbuild
Target board Seeed XIAO nRF54LM20A Sense on-board LSM6DS3TR-C, MSM261DGT006, nPM1300
External sensor SHT40 I²C 0x44, on the XIAO I²C header
BLE beacon format version 2 29 bytes, backward-compatible with the v1 26-byte prefix
Identity record version 1 board ID 2, major/minor/patch
Bootloader MCUboot (dual-slot, 449 KiB per slot) via sysbuild
Enclosure 3D-printable, XIAO + SHT40 + 500 mAh LiPo enclosure/
Requires HiveHub V0.4 or newer for identity readout, version gating and OTA relay

The firmware version string (0.4.x) is the firmware's own counter and is
independent of this repository release tag (V0.1).

Quick start

west init -m https://github.com/MacNite/HiveInside hiveinside-workspace
cd hiveinside-workspace && west update
west build --sysbuild -b xiao_nrf54lm20a/nrf54lm20a/cpuapp -d debug hiveinside/firmware-nrf54lm20a
west flash -d debug
picocom -b 115200 /dev/ttyACM0

--sysbuild is not optional: the firmware boots through MCUboot, so a
bootable device needs the bootloader and the signed application, and only a
sysbuild build produces both (plus the OTA payload). A plain west build yields
an application-only image with nothing at 0x0, which does not boot.

For a hive deployment, build the lowpower profile and flash that image —
then let HiveHub keep it up to date over the air.

Status & known limitations

  • The firmware is complete and OTA is verified on hardware. Long-term field
    validation in a live colony is still ongoing     — treat V0.1 as a solid first
    release, not as a multi-season-proven product.
  • The measurement advertisement fills the 31-byte legacy limit exactly, so the
    optional BLE Flags element is omitted. The node is therefore formally
    non-discoverable: generic scanner apps that filter on the discoverable bits
    may not list it. HiveHub's passive scan and a direct connect by address are
    unaffected.
  • Idle current is an audit based on component and configuration analysis; a
    power-analyzer measurement of the assembled board is still the number that
    counts.

License

MIT — see LICENSE.

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