TORUS-SN is a battery-operated, multi-modal wireless security sensor node. It detects ground vibration through an external 4.5 Hz geophone, captures stereo audio through a MEMS microphone pair, and reports events to a TORUS-MEG gateway over 433 MHz LoRa (EU ISM). A Semtech LR1110 additionally provides multi-constellation GNSS scanning and passive WiFi-AP scanning for low-power geolocation.
A hardware wake-on-seismic path (comparator on the analog front-end output) wakes the system from deep sleep without CPU involvement. Each sensing subsystem is gated by its own load switch. Single-cell Li-ion operation with onboard USB-C charging.
| Subsystem | Ref | Device | Detail |
|---|---|---|---|
| Host MCU | U1 | ESP32-S3-WROOM-1 | Dual-core Xtensa LX7, WiFi 2.4 GHz + BLE 5; module substituted for spec'd ESP32-S3-MINI-1 (see §8) |
| LoRa / GNSS / WiFi-scan | U2 | Semtech LR1110 (QFN32) | LoRa 433 MHz uplink, GNSS + WiFi-AP scan geolocation; 32 MHz TCXO (X1) mandatory for GNSS |
| Seismic AFE | U3, U4 | OPA2134 + MCP4017-104 | Low-noise dual op-amp; 100 kΩ 7-bit I2C digital potentiometer for gain |
| Wake comparator | U11 | LM393 | Hardware wake-on-seismic against a set threshold |
| Microphones | MK1, MK2 | 2× InvenSense INMP441 | 24-bit I2S MEMS, omnidirectional, wired as stereo pair |
| RTC | U5 | DS3231SN | ±2 ppm TCXO RTC, I2C; CR1220 backup (BT1); 32 kHz out feeds LR1110 |
| Battery charger | U7 | TP4056 | Single-cell Li-ion, charge current set to 1 A (R17 = 1.2 kΩ); CHRG/STDBY LEDs |
| Regulator | U6 | AMS1117-3.3 | 3.3 V LDO, 1 A max |
| Load switches | U8-U10 | 3× TPS22918 | Independent gating of seismic, acoustic, and LR1110 rails |
| RF front end | SW1, SW2, U_LNA | 2× SKY13350 + SPF5189Z | TX/RX switching for the 433 MHz path; LNA on the GNSS path |
| Ref | Type | Function |
|---|---|---|
| J1 | USB-C receptacle | 5 V charge input; USB data to MCU (see §8 note on GPIO mapping) |
| J2 | SMA edge-mount | 433 MHz LoRa antenna |
| J3 | JST-PH 2-pin | Single-cell Li-ion battery |
| J4 | Phoenix 3.5 mm terminal, 3-pos | External geophone (R.T. Clark 4.5 Hz 375 Ω vertical, or equivalent) |
| J5 | Tag-Connect TC2030 (DNP) | JTAG / programming |
| ANT1 | FXP73 chip antenna land | WiFi-scan RF (LR1110 HF path) |
| BT1 | CR1220 holder | RTC backup cell |
| D1 / D2 | LED red / green | Charge status (TP4056 CHRG / STDBY) |
| Parameter | Min | Typ | Max | Unit | Notes |
|---|---|---|---|---|---|
| Battery input (VBAT) | 3.0 | 3.7 | 4.2 | V | 1S Li-ion, J3 |
| USB input (VBUS) | n/a | 5.0 | n/a | V | J1 |
| Main rail (VCC_3V3) | n/a | 3.3 | n/a | V | AMS1117, 1 A max |
| Charge current | n/a | 1.0 | n/a | A | TP4056, R17 = 1.2 kΩ |
| Deep-sleep current | TBD | µA | Pending board bring-up; see §8 note 7 | ||
| Active TX current | TBD | mA | Pending characterization | ||
Values on unbuilt hardware are design values, not measurements. This document describes a pre-production design that has not yet been fabricated.
| Parameter | Value |
|---|---|
| Board dimensions | 80.0 × 55.0 mm, 3.0 mm corner radius |
| Stack-up | 4-layer: signal / GND plane (In1) / 3V3 plane (In2) / signal, GND fill front & back |
| Mounting | 4× M2.5 (2.7 mm holes), 73 × 48 mm pattern |
| Antenna provisions | SMA (433 MHz), FXP73 land (WiFi scan), GNSS antenna path; pour keepouts under all antennas |
The node runs Zephyr RTOS. Hardware design data is fully generated: a single Python source of truth (torus_design.py, 91 parts / 68 nets) emits the KiCad 10 schematic and PCB, with autorouting via Freerouting. Schematic ERC: clean. Netlist parity between schematic and layout holds by construction.
TORUS is an independent platform. Company names and product model numbers referenced in this document (including but not limited to Semtech (LR1110), Teledyne FLIR, R.T. Clark, InvenSense (INMP441), Texas Instruments (OPA2134, TPS22918, LM393), Microchip (MCP4017), Espressif (ESP32-S3), Analog Devices / Maxim Integrated (DS3231), and their respective product identifiers) are used solely for engineering and bill-of-materials identification. Their use does not imply any affiliation with, sponsorship by, or endorsement by those companies. Supply of any such third-party product or component to the designers, manufacturers, integrators, or evaluators of the TORUS platform remains at the sole discretion of the respective owning company, organisation, or legal entity. All trademarks are the property of their respective owners.