A custom communication module for gate controllers based on the ESP32-C6 and implementing the Zigbee 3.0 protocol. It converts an offline gate controller into a smart device that can be integrated with Home Assistant (ZHA).
The project was primarily dedicated for Key Automation 900CT driver, but ultimately it could be used with any gate or garage door controller with +24 V I/O with:
- inputs that are triggered by pulling the line to COM/GND (sinking / contact-closure),
- outputs that assert a +24 V signal (active-high).
This repository contains both the hardware schematics (soon) and firmware for the project.
The module includes following features:
- Dimensions 65 mm × 71.4 mm
- Required power supply:
- from 8V up to 40V
- min. 1.3W (up to 11W when
J1is used)
- UART interface (
J2) - Buck power switch (
SW1) - Power source switch (
JP1, buck or UART) +5V, 1.5Apower output for external device onJ1- RGB LED indicator
- Thermometer (
DS18B20+) - Buttons:
RESETBOOT/GPIO9
- 4 × opto-isolated 24 V digital outputs (open-collector / sinking, pull-to-GND)
- 2 × opto-isolated 24 V digital inputs (active-high, voltage applied w.r.t. GND)
- 2 × separated GNDs for input and output channels
The PCB has a nominal outline of 65 mm × 65 mm. Due to the recommended RF keep-out, the ESP32-C6 antenna protrudes beyond one edge, resulting in an overall maximum dimension of 71.315 mm in that direction.
The board provides 4 × M4 mounting holes arranged in a 55 mm × 55 mm square pattern (center-to-center). Each hole center is located 5 mm from the adjacent PCB edges.
The overall assembly height depends on the population; the tallest component is the LM2676T-5.0 (TO-220) mounted in the standard upright orientation. Proposed layout shown below.
Module is powered with buck converter based on LM2676T-5.0, working from 8 up to 40 V DC. Some controllers might output only AC for external modules via terminals (like Key Automation 900CT-2), or doesn't include any low-voltage output at all. In above cases, it's required to use bridge rectifier with proper protection or separate power supply (8 - 40 V DC). Power for the buck converter is supplied via screw terminal.
Device includes 5V 1.5A protected output (J1) for external devices and debugging circuits. This port shouldn't be used as 5V power input for this module.
Main part of the device (ESP32-C6, LED, thermometer) is powered with 3.3 V LDO (LM1117-3.3). Alternately, 3.3 V from UART can be used during debugging. Power source can be switched by setting jumper on JP1.
The module interfaces 24 V control signals with an ESP32 (3.3 V logic). It provides low-side (sinking) control outputs and opto-isolated 24 V inputs, ensuring galvanic isolation between the 24 V I/O domain and the MCU. All channels are routed to screw terminals for easy wiring. The input and output interfaces use separate isolated commons (COM), independent from the module power ground, which improves compatibility with different controllers and wiring schemes.
The whole module is fused for 3 A, but doesn't include any kind of polarity protection. The user should provide proper wiring and stable, appropriately rated power supply for the device to operate as intended.
This module was designed from the start for Home Assistant using the ZHA integration. Zigbee 3.0 was chosen to avoid adding more devices to an already busy 2.4 GHz Wi-Fi network, which can negatively impact range and overall performance - especially in homes with many IoT endpoints. While Zigbee is common for small sensors, many larger products (e.g., gate controllers, thermostats, boilers) are still frequently offered as Wi-Fi-only, making Zigbee-based alternatives useful.
Software includes following features:
- Zigbee 3.0 implementation with standard clusters
- 3 basic commands:
Open gateClose gateStop gate(active-low)
- Beam sensor state reading
- RGB LED driver for device's state indication:
- Zigbee connection state
- Command state
- Beam sensor state
- Device temperature reading
- Device configuration in Home Assistant (only with ZHA quirk)
- Gate operation time (open/close gate lock to avoid gate state problems)
- Beam sensor reaction time (miliseconds) to configure sensitivity
Firmware was prepared using ESP-IDF framework and supports FreeROTS tasks.
The module in current version is able to send 3 commands to the slave-controller. Each of them simulate short signal from RF pilot (which was originally used with gate controller), persisting for 200ms.
The open gate and close gate control signals are active-high from the ESP32-C6 side. The stop gate signal is an exception: it is active-low fail-safe on the external controller side, meaning the controller is stopped whenever this line is driven low (or left low), so its working mode is inverted.
The module is able to utilize driver's beam sensor as standard Zigbee occupancy sensor. Input is filtered with debounce factor configurable in Home Assistant device's page.
This feature lets user send all basic gate command. User can request opening, closing or stopping gate from moving. Stop command is never locked.
This feature lets user peek on beam sensor's state. Home Assistant will automatically collect all action in history.
This feature lets user check current device's temperature. Thermometer is located in the middle of the board, between power supply and ESP32-C6 chip. Again, Home Assistant will automatically collect temperature history. When quirk is used, this entity should be shown under Configuration card.
This feature lets user configure device. For now there are only two options:
- Gate's working time - time needed for gate to open/close (milliseconds). This feature locks open and close command for driver's operation time.
- Beam sensor's debounce - time (milliseconds) after which signal from beam sensor is considered as serious action, not just interference. Signals shorter than set value will be ignored.
TBD
TBD
The module was tested for 4 months, using a prototype based on Seeed Studio XIAO ESP32C6 development board. For this time, device was working almost uninterrupted, causing very few issues corrected in a final prototype (proper PCB).
Images below depicts the first prototype and the second prototype.
