• Installed in its own IP-rated outdoor enclosure near an existing gate operator.
• Interfaces only with the gate controller's low-voltage command and status terminals.
• Does not drive the gate motor or replace obstruction detection, limits, emergency release, or certified safety controls.
• Initial prototype with production-intent architecture.

• Operate from either polarity of 12–24 VDC or from 12–24 VAC.
• Receive authenticated remote commands over Wi-Fi, with optional cellular failover.
• Pulse independently configurable OPEN and CLOSE dry-contact outputs.
• Report open-limit and closed-limit contact states.
• Default to relay-off after reset, power loss, watchdog reset, or communication loss.
• Support secure firmware updates and local programming/debug.

• ESP32-S3 Wi-Fi MCU module with pre-certified radio and external-antenna option preferred.
• Two normally-open, galvanically isolated relay outputs with COM/NO terminals.
• Two galvanically isolated dry-contact status inputs.
• Plug-in LTE-M/NB-IoT modem interface using UART plus a high-current 5 V supply; USB data is desirable if practical.
• Reset/boot controls, status indicators, watchdog-capable firmware, and service connector.
• Input fuse, surge suppression, bridge rectification, reverse-polarity tolerance, and wide-input conversion.

Diagram

• Pluggable two-position field terminal.
• 12–24 VAC or DC, polarity independent.
• Resettable or replaceable input fuse sized from the final power budget.
• Bridge rectifier rated for at least 60 V reverse voltage and worst-case input current.
• TVS/MOV strategy appropriate to low-voltage outdoor wiring; final surge level to be validated during compliance testing.
• Bulk capacitance after the bridge sized for 12 VAC operation and transient loads.

• Wide-input 5 V switching regulator rated above the modem-plus-system peak.
• Separate 3.3 V switching regulator for the ESP32 and logic to avoid excessive LDO dissipation.
• Power-good/brownout behavior must leave relay outputs inactive.

• ESP32-S3 module rather than a bare RF IC.
• Boot and reset circuitry per Espressif guidance.
• Native USB or protected programming header.
• Hardware GPIO assignments must avoid boot-strapping conflicts.

• Two independent normally-open relay contacts, each exposed as COM and NO.
• Firmware-configurable labels/functions: OPEN/CLOSE or two OPEN channels.
• Relay drivers include default-off bias and coil flyback suppression.
• Contacts are dry and isolated from board power.

• Two isolated channels for volt-free OPEN-LIMIT and CLOSED-LIMIT contacts.
• Board supplies wetting current through an isolated input circuit; field wiring must not connect directly to ESP32 GPIO.
• Input filtering/debounce supports long outdoor cable runs.

• Plug-in carrier/modem for US LTE-M/NB-IoT service.
• 5 V supply budgeted for 2 A transient demand unless the selected carrier specifies less.
• UART interface with level compatibility and hardware flow control where available.
• External antenna connector is expected on the modem module/carrier.

• Continuous operation from the gate operator's auxiliary supply; no onboard battery in revision 1.
• Wi-Fi is primary. Cellular is normally standby and may create short high-current transmit bursts.
• Relays should normally be pulsed for approximately 0.5–2 seconds, configurable in firmware.

• Professional SMD assembly; pluggable field terminals may be through-hole.
• Industrial-temperature components preferred (-40 to +85 °C minimum where practical).
• Conformal coating compatible footprint spacing and keepout around connectors/buttons.
• Four mounting holes and a 2- or 4-layer PCB; 4 layers preferred for RF, EMC, and robust grounding.

• Outputs initialize inactive before application firmware runs.
• Independent commands, pulse timers, interlock policy, and event logging.
• Input debounce and invalid-state detection (both limits active or neither active for too long).
• Wi-Fi provisioning, TLS-authenticated backend communication, signed OTA updates, watchdog recovery, and cellular failover.
• Close commands must never bypass the gate operator's obstruction/safety system.

• Sized for an IP65/IP67 enclosure; exact dimensions remain open until enclosure selection.
• Field terminals along board edges and clearly separated by function.
• ESP32 antenna at an enclosure-facing board edge with copper keepout; external antenna module variant preferred for metal enclosures.
• LTE antenna is external through the plug-in modem.

• The board controls low-voltage dry-contact inputs only; it never switches motor power.
• Universal AC/DC input uses a bridge rectifier.
• Two independent relays support controllers with separate OPEN/CLOSE inputs and installations needing two OPEN channels.
• Cellular remains modular to reduce certification risk and simplify carrier/module upgrades.
• Isolation is used on all gate status inputs and inherent in relay contacts.

• Gate auxiliary power can supply at least 2 A at 12 V when the cellular modem is fitted; otherwise a separate supply is required.
• Gate command inputs accept a momentary normally-open contact closure.
• Status outputs are volt-free contacts. Powered status outputs require a future input variant or external interface.
• The existing gate operator retains all UL 325/ASTM F2200 safety functions and automatic-close logic.
• North American deployment is the initial target.

• Powers reliably from 12 VAC, 24 VAC, 12 VDC, and 24 VDC across tolerance.
• No relay activation during power-up, reset, brownout, firmware update, or loss of network.
• Each relay can be commanded independently and contacts remain electrically isolated.
• Both position inputs correctly report open/closed contact states.
• Wi-Fi operation is functional and the cellular connector can support an LTE-M/NB-IoT carrier without brownout.
• Schematic review has no unresolved critical electrical errors before PCB layout.

• Initial specification created from the user-approved architecture on 2026-07-28.