CollarID — Hardware Datasheet

Overview

CollarID Mk II is a low-power, GPS-tracked wildlife monitoring collar for behavioural and environmental research. It combines a multi-channel sensor suite (3-axis accelerometer, magnetometer, lux, environmental T/H/P/gas, particulate, MEMS microphone) with solar-augmented battery operation and dual BLE + LoRa/LoRaWAN radios. Data is logged to a microSD card on-device and summary statistics are uplinked over LoRa for in-deployment monitoring.

The hardware is built on a 3-board stack: a CPU board carrying the main MCU, sensors, SD card, USB-C and audio paths; a top board with GPS, BLE, LoRa, charge management, and the user-facing power switch; and a flex board with the PDM microphone and the environmental sensor.

Block Diagram

Physical & Mechanical

Form factor	Collar-mounted enclosure with integrated solar cell
Cover material	Polycarbonate
Base material	Machined anodized aluminum
Sealing	EPDM gasket compressed by six stainless perimeter screws. In-house bench testing: two consecutive cycles of pressurised warm-water spray (~55–65 °C) with alkaline surfactant detergent and full thermal cycle — no ingress, no post-test functional degradation.
Dimensions	87 mm long × 40 mm wide × 24 mm tall (centre) / 31 mm tall (edges); length excludes the flanged ends used for M5 mounting screws
Mounting	M5 through-holes on each flanged end, 30 mm centre-to-centre
Weight	150 g
Ingress protection	Formal IPX certification planned
Operating temperature	−20 °C to +60 °C
Storage temperature	−40 °C to +85 °C
Field placement	Animal collar strap (upper hemisphere recommended for solar exposure)

Power & Battery

Battery chemistry	Li-ion / LiPo
Battery capacity	2.96 Wh
Battery voltage	2.8 V (cutoff) — 4.2 V (full charge)
Low-battery hibernation	Firmware enters hibernation at ≤ 10 % SoC. The device wakes every 8 hours to re-check the battery and resumes normal operation when SoC has recharged above 20 %. With adequate solar exposure, hibernating units self-recover in the field without intervention.
USB-C charger	400 mA charge current (≈ 0.5 C, 2-hour full-charge profile)
Solar harvester	Boost charger driving the same battery; tolerates partial-shading conditions typical of foliage canopies
Solar cell	Integrated panel on enclosure cover (mount upper-hemisphere on animal for best yield)
Power architecture	Per-subsystem energy budget. Radios, sensors, MCU duty cycles, file system, and peripheral wake/sleep are each individually budgeted and hand-tuned against their physical lower bound. The configurator's Power tab exposes the same per-subsystem equation the firmware uses for schedule planning.
Field-validated cadence	GPS fix + LoRaWAN uplink every 5 minutes, sustained for several consecutive months on a free-grazing cattle deployment. Achievable cadence in any deployment depends on solar exposure, animal behaviour, and gateway coverage.
Field life	Highly schedule-dependent. The configurator's Power tab displays an estimated longevity for each schedule across open-sky and canopy conditions.

Compute

MCU	32-bit Arm Cortex-M33 with FPU
Flash	4 MB internal
RAM	2.5 MB internal SRAM
RTC	Real-time clock included
BLE module	Separate BLE module

Wireless

Bluetooth Low Energy

Standard	BLE 5.x
Use	Schedule configuration and firmware updates via the configurator
Range	Phone-side dependent; typical ≥ 10 m line-of-sight outdoors
Antenna	Module-integrated
Activation	Auto on fresh-SD boot, or magnet swipe over the paw-print LED at any time

LoRa / LoRaWAN

Radio	Long-range sub-GHz LoRa transceiver
Frequency bands	868 MHz and 915 MHz sub-GHz, build-time configurable. In LoRa P2P mode the carrier frequency is freely user-configurable; the LoRaWAN regional presets (`US915`, `EU868`, `AU915`) apply only when running the LoRaWAN stack.
Antenna	Chip antenna
Spreading factors	SF7 — SF12
Bandwidth	125 / 250 / 500 kHz
Coding rate	4/5, 4/6, 4/7, 4/8
Modes	LoRaWAN (Class A) with OTAA or ABP activation, or peer-to-peer LoRa

GPS / GNSS

Receiver	Multi-GNSS receiver
Constellations	GPS, GLONASS, Galileo, BeiDou (concurrent multi-GNSS)
Antenna	Active patch
Cold-start TTFF	Typical ≤ 30 s with clear sky
Hot-start TTFF	Typical < 5 s
Position accuracy	≤ 1.5 m CEP, open sky
Time accuracy	30 ns RMS; used for RTC sync and time-pulse output

Sensors

Accelerometer

Type	3-axis MEMS, ultra-low-power
Range options	±2 g (1024 LSB/g) · ±4 g (512 LSB/g, default) · ±8 g (256 LSB/g)
ODR options	25 / 50 (default) / 100 / 200 / 400 / 800 Hz
Resolution	12-bit, sign-extended to int16 in WAV files
Configuration	Per-schedule via configurator
On-device DSP	ODBA / VeDBA windowed mean & max (planned, live computation TBD); intended for periodic LoRa uplinks

Magnetometer

Type	3-axis MEMS magnetometer
Range	±50 gauss
Resolution	1.5 mGauss / LSB
Magnet trigger	Used as magnet-presence detector for BLE-mode wake-up

Environmental

Sensors	Temperature, humidity, pressure, gas (VOC) resistance
Pressure range	300 — 1100 hPa
Humidity range	0 — 100 %RH
Temperature range	−40 °C to +85 °C
Calibration	BSEC2 library on-device
Logged signals	`COMP_T` (°C), `COMP_H` (%RH), `RAW_GAS` (Ω), `RAW_P` (Pa)

Particulate — optional

Not included in the standard stock configuration. Available as an optional add-on for deployments that need particulate-matter monitoring.

Type	Laser-scattering MEMS particulate matter sensor
Channels	PM1.0, PM2.5, PM10 (µg/m³)
Power cycling	Default 15-minute duty cycle, per-schedule configurable

Lux

Type	Ambient light sensor
Channels	Clear + ALS (lux)
Resolution	16-bit, configurable gain & integration time

Audio

Microphone	Knowles `SPH0641LU4H-1` PDM digital MEMS
Frequency response	100 Hz — 80 kHz (per the microphone datasheet) — sensitive into the ultrasonic range
Default sampling	16 kHz, 16-bit signed mono PCM (audible band, 0 — 8 kHz Nyquist)
Higher sampling rates	The microphone itself supports much higher rates than the default. Capturing the ultrasonic band (e.g. 96 kHz / 192 kHz sampling) is possible but requires a custom firmware build — it is not exposed in the standard configurator UI.
Storage	Per-schedule recording windows; one WAV per window

Storage

Slot	microSD push-push socket
Filesystem	exFAT
Tested capacity	Up to 2 TB
Recommended cards	Industrial-grade Kioxia (primary). Limited testing on SanDisk. Other brands not recommended.
Interface	4-bit SDIO, level-shifted, dedicated 3.0 V LDO
Schemas written	`config.csv`, `METADATA.CSV`, `lora_state.bin`, `/audio/…`, `/accelerometer/…` — see Data Schema

I/O & Indicators

USB-C	USB-C connector used for charging and firmware updates (DFU). Cover must be removed to access — no pass-through. ESD-protected.
Status LED	RGB SMD LED driven by three low-side N-FETs. Mounted under the paw-print on the cover, visible through polycarbonate.
Charge LEDs	Discrete red + green, located near the USB-C port; visible through the closed cover.

User Controls

Power switch	SPDT slide switch on top board (cover-off access only). ON/OFF labelled in silkscreen on the front PCBA.
Magnet trigger	Hold any magnet (N52 ideal, refrigerator-grade often sufficient) over the paw-print LED for ≥ 3 s, then remove, to reboot the device into BLE mode. Works with the cover on.

Firmware / Software

RTOS	Azure RTOS ThreadX
File system	Azure RTOS FileX (FAT/exFAT)
Firmware updates	Web-based DFU (Chrome/Firefox) over USB-C with BLE handshake; see Device Manual
Source availability	Closed-source. Protobuf message definitions and supporting decoder/integration material are available on request — [email protected].

Certifications

FCC	TBD
IC (Canada)	TBD
CE	TBD
Module-level certs	TBD — integrated module FCC/IC/CE IDs to be listed when end-product certification is finalised

End-product certification is in progress. Devices are currently provided for research use only and should not be operated in commercial deployments until certifications are finalised.

Roadmap

The following are in active development and not part of the current Mk II hardware. Listed here so deployment planners can factor them into multi-season studies.

Automated drop-off mechanism	In pilot testing. Programmable release for non-recoverable or hard-to-recover deployments.
Satellite uplink	In development as a modular add-on node, separate from the base CollarID Mk II hardware. Intended for deployments without LoRa / LoRaWAN gateway coverage.

Revision History

Hardware rev	Date	Notes
Rev B	—	Current production hardware (Mk II).

Citation

If CollarID Mk II appears in a publication, please report:

Hardware revision (Rev B)
Firmware version (the firmware_version field in the device's config.csv; see the Changelog)
Per-schedule sensor configuration (the relevant rows of config.csv)
SD card brand and capacity

A canonical citation block (BibTeX) will be published alongside the formal release announcement.