ESP32H2 Gas Counter with Zigbee2MQTT

ESP32H2-based pulse counter that measures pulses from utility meters with magnetic impulse output and sends them to Zigbee2MQTT.

Inspired by ZigbeeGasCounter.

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🚀 Quick Start

1. Flash the firmware onto your ESP32-H2 board.
2. Copy the external converter to Zigbee2MQTT.
   👉 See External Converter
3. Restart Zigbee2MQTT completely (full restart required).
4. Enable Zigbee pairing (permit join)
5. Power on the board or press the Boot button to send the first data packet.

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⚠️ Power Notes

• The vBat pin operates at VDD levels (typically 3.3V).
• The pin vBat is NOT 5V tolerant.
• To reduce power consumption, the power LED may be removed (unsoldered).
• Use a voltage regulator or voltage divider if needed.
• Can also be powered from USB (3.3V internally regulated).

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✨ Features

• Counts pulses from a meter using a reed sensor connected to a GPIO and GND pin.
• Stores pulse count in non-volatile memory (NVS).
• Sends data to Zigbee2MQTT:
  • On a configurable timer
  • When accumulated pulses reach a threshold
  • Triggers immediate transmission when Boot button is pressed
• Supports deep sleep for low power.
• LED for pulse indication.

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🔧 Hardware

• ESP32-H2-DevKitM-1 internal antenna / ESP32-H2-DevKitM-1 external antenna board (4MB Flash)
• Gas meter with pulse output (e.g., BK-G4MT, Honeywell BK-G6M or similar)
• Reed sensor (10AT is better): Normally Open (NO) – tested with GPS-01 Reed Switch 4×18 (not quite sensetive)
• Battery power supply (supports USB-C power banks)

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📦 Software Requirements

• Zigbee2MQTT with external converter configured
• ESP-IDF (used in installation by ESP-IDF)
• MQTT broker
• Home Assistant server

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🔌 Wiring Example

ESP32H2 Pin	Connection
GPIO10	Reed sensor signal
GND	Reed sensor GND
VBat(Vcc)	+VDD (+3.3V)
GND	Battery '-'

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⚙️ Configuration

Parameter	Description
PULSE_PIN	GPIO pin connected to the reed sensor
MAIN_BTN	GPIO used for the button
MUST_SYNC_MINIMUM_TIME	Interval between automatic transmissions (default: 60 min)
COUNTER_REPORT_DIFF	Number of pulses to trigger immediate transmission (default 10)
INITIAL_COUNTER_VALUE	Initial counter value (e.g., 2134 = 21.34 m³)
FEATURE_MEASURE_BATTERY_LEVEL	Enable or disable battery voltage monitoring
ADC_CHANNEL_2	GPIO pin used to measure voltage via a resistive divider
RATED_BATTERY_VOLTAGE	Nominal battery voltage (as specified by the manufacturer)
MAX_BATTERY_VOLTAGE	Maximum battery voltage
MIN_BATTERY_VOLTAGE	Minimum battery voltage
WARN_BATTERY_VOLTAGE	Battery voltage threshold for warning
ADC_MAX_VALUE	Maximum ADC value (on GPIO pin used to measure voltage)

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🚀 How It Works

1. ESP32H2 counts pulses from the meter.
2. Pulses are stored in NVS flash to survive reboots or deep sleep.
3. When timer expires or pulse threshold is reached data is sent to Zigbee2MQTT.
4. Device enters deep sleep to save power until next event (pulse or timer).

🏠 Home Assistant Configuration

To correctly interpret the counter values as gas consumption, create a Helper in Home Assistant Settings → Devices & services → Helpers → Create helper → Template → Sensor with the following parameters.

5720.17 - is the initial reading of your utility meter.
sensor.0xf4ce3662f44a0e45_gas_count - your sensor entity in Home Assistant.

📊 Template

Name: Gas meter
State: {{ (states('sensor.0xf4ce3662f44a0e45_gas_count') | float(0) * 0.01 + 5720.17) | round(2) }}
Device class: Gas
State class: Total increasing
Unit of measurement: m³
Availability template: {{ has_value('sensor.0xf4ce3662f44a0e45_gas_count') }}

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📟 Example Logs

GAS_COUNTER: Counter loaded value=160
GAS_COUNTER: Setup deep sleep
GAS_COUNTER: Wake up from PULSE.
GAS_COUNTER: Checking if Zigbee radio should be enabled
GAS_COUNTER: Counter stored value=161
GAS_COUNTER: Configuring wake-up methods
GAS_COUNTER: Enabling wake-up timer , 162s

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⚡ Installation

⚠️ Don't forget to create an external converter in Zigbee2MQTT first!

1️⃣ Using ESP-IDF (recommended)

• git clone https://github.com/romlisrl/Esp32H2GasCounter
• cd Esp32H2GasCounter
• Set the desired configuration values
• idf.py erase-flash
• idf.py build flash

2️⃣ Using esptool.py (firmware_batmon.bin/firmware_wo_batmon.bin)

• Connect the board to a UART port (e.g., COM10 on Windows)

With battery monitor:

esptool.py --chip esp32h2 --port COM10 write_flash 0x0 firmware_batmon.bin  

Without battery monitor:

esptool.py --chip esp32h2 --port COM10 write_flash 0x0 firmware_wo_batmon.bin  

3️⃣ Using ESPHome Web (firmware_batmon.bin/firmware_wo_batmon.bin)

• Connect the board via USB/UART
• Select the firmware file:
  • firmware_batmon.bin (with battery monitor)
  • firmware_wo_batmon.bin (without battery monitor)
• Flash it directly from the browser

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🛠️ To Be Done

The following tasks are planned or pending implementation:

• [х] Implement battery voltage measurement via voltage divider on GPIO3 — include ADC reading and calibration.
• [х] Add configuration for voltage divider parameters (scaling factor, low-battery thresholds).

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📝 Notes

• Make sure the Zigbee coordinator is running and permit join is enabled
• After modifying the external converter, restart Zigbee2MQTT completely (do not use Settings → Tools → Restart Zigbee2MQTT)