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Shelly EM Gen3

Device Type:sensor
Electrical Standard:aubreuinukusglobal
Board:esp32
Difficulty:Plug-n-flash (2/5)

Shelly EM Gen3 Product Image

GPIO Pinout

PinFunction
GPIO0Relay
GPIO1Button
GPIO3ADC for NTC temperature sensor
GPIO4ADE7953 IRQ pin (active low)
GPIO5ADE7953 RESET pin (active low)
GPIO6I2C SCL
GPIO7I2C SDA
GPIO9Status LED
GPIO18Pin 1 of 7-pin header
GPIO20UART receive (U0RXD)
GPIO21UART transmit (U0TXD)

I2C Devices

AddressFunction
0x38ADE7953 power sensor
0x51AiP8563 RTC (not currently supported by ESPHome)

Quick start / Example config

Note that you should set AP & OTA passwords before using any ESPHome device in production.

Minimal (hardware definitions only)

# Shelly EM Gen3 - Minimal (Hardware definitions only)
# Model number: S3EM-002CXCEU50
# PCB markings: "EM Gen3_v0.1.3", "B2519"
# SoC: ESP-Shelly-C38F (similar to ESP32-C3)
# CPU: ESP32-C3 (QFN32) (revision v0.4)
# Features: Wi-Fi, BT 5 (LE), Single Core, 160MHz, Embedded Flash 8MB (GD)
# Crystal frequency:  40MHz
# References:
# - https://devices.esphome.io/devices/shelly-em-gen3/
# - https://community.home-assistant.io/t/shelly-em-gen3-solved/944171
# - https://kb.shelly.cloud/knowledge-base/shelly-em-gen3
#
# GPIOs:
#   GPIO0 - Dry-contact relay (normally open)
#   GPIO1 - Pushbutton
#   GPIO3 - ADC for NTC temperature sensor
#   GPIO4 - ADE7953 IRQ pin (active low)
#   GPIO5 - ADE7953 RESET pin (active low)
#   GPIO6 - I2C SCL
#   GPIO7 - I2C SDA
#   GPIO9 - Status LED (active low)
#   GPIO18 - Pin 1 of 7-pin header
#   GPIO20 - UART receive (U0RXD)
#   GPIO21 - UART transmit (U0TXD)
#
# I2C devices:
#  0x38 - ADE7953 Power Sensor
#  0x51 - AiP8563 Battery-backed real-time clock (not currently supported by ESPHome)


substitutions:
  # How often to update the power meter.
  update_interval: 20s


  # Calibrated on US-style 120V power with 50A current transformers.
  # You may need to calibrate this yourself if the numbers are inaccurate.
  calibration_voltage_gain: 0x32c78f
  calibration_current_gain_a: 0x490bb5
  calibration_current_gain_b: 0x498c15


esphome:
  name: "shelly-em-gen3"
  friendly_name: "Shelly EM Gen3"
  comment: "Shelly EM Gen3 - Smart wifi and bluetooth energy meter with dual current transformers"
  name_add_mac_suffix: true
  min_version: 2025.11.3    # for ade7953 bugfix #12180


esp32:
  variant: esp32c3
  flash_size: 8MB
  framework:
    type: esp-idf


# Enable logging
logger:
  level: DEBUG
  hardware_uart: uart0


# debug:


# Enable Home Assistant API with dynamic key
api:
  encryption:


ota:
  - platform: esphome
    id: ota_id
    # password: !secret ota_password


wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password


i2c:
  scl: GPIO6
  sda: GPIO7
  scan: true


light:
  - platform: status_led
    name: "Status LED"
    id: status_led_id
    disabled_by_default: true
    entity_category: diagnostic
    pin:
      number: GPIO9
      inverted: true
      ignore_strapping_warning: true


switch:
  # Dry-contact relay - normally open
  - platform: gpio
    name: Relay
    id: relay_id
    pin: GPIO0


sensor:
  - platform: ntc
    id: ntc_temperature
    name: "NTC Temperature"
    entity_category: diagnostic
    unit_of_measurement: "°C"
    accuracy_decimals: 1
    icon: "mdi:thermometer"
    sensor: temp_resistance_reading
    calibration:
      b_constant: 3350
      reference_resistance: 10kOhm
      reference_temperature: 298.15K
  - platform: resistance
    id: temp_resistance_reading
    sensor: temp_analog_reading
    configuration: DOWNSTREAM
    resistor: 10kOhm
  - platform: adc
    id: temp_analog_reading
    pin: GPIO3
    attenuation: 12db


  # Note that on the Shelly EM Gen3, channels "A" and "B" are swapped between the chipset and the labels on the device.
  # The nIRQ pin of the ade7953 device seems to be connected to pin 9 (GPIO4)
  # of the ESP-Shelly-C38F.
  - platform: ade7953_i2c
    id: ade7953_id
    irq_pin: GPIO4
    update_interval: ${update_interval}
    use_accumulated_energy_registers: true


    voltage_gain: ${calibration_voltage_gain}
    current_gain_a: ${calibration_current_gain_a}
    current_gain_b: ${calibration_current_gain_b}


    voltage:
      id: line_voltage
      name: Voltage
    frequency:
      id: line_frequency
      name: Frequency
    current_b:
      id: current_a
      name: "Current A"
      accuracy_decimals: 3
    current_a:
      id: current_b
      name: Current B
      accuracy_decimals: 3
    power_factor_b:
      id: power_factor_a
      name: "Power Factor A"
      filters:
        - multiply: -1
    power_factor_a:
      id: power_factor_b
      name: "Power Factor B"
      filters:
        - multiply: -1
    apparent_power_b:
      id: apparent_power_a
      name: "Apparent Power A"
    apparent_power_a:
      id: apparent_power_b
      name: "Apparent Power B"
    active_power_b:
      id: active_power_a
      name: "Power A"
    active_power_a:
      id: active_power_b
      name: "Power B"
    reactive_power_b:
      id: reactive_power_a
      name: "Reactive Power A"
      filters:
        - multiply: -1
    reactive_power_a:
      id: reactive_power_b
      name: "Reactive Power B"
      filters:
        - multiply: -1


binary_sensor:
  - platform: gpio
    id: shelly_button_id
    name: "Button"
    entity_category: diagnostic
    pin:
      number: GPIO1
      inverted: true
      mode:
        input: true
        pullup: true
    filters:
      - settle: 10ms


  - platform: gpio
    id: binary_sensor_header_gpio_id
    name: "Header GPIO"
    entity_category: diagnostic
    disabled_by_default: true
    pin:
      number: GPIO18
      inverted: true
      mode:
        input: true
        pullup: true

Full example (includes energy monitoring)

# Shelly EM Gen3
# Model number: S3EM-002CXCEU50
# PCB markings: "EM Gen3_v0.1.3", "B2519"
# SoC: ESP-Shelly-C38F (similar to ESP32-C3)
# CPU: ESP32-C3 (QFN32) (revision v0.4)
# Features: Wi-Fi, BT 5 (LE), Single Core, 160MHz, Embedded Flash 8MB (GD)
# Crystal frequency:  40MHz
# References:
# - https://devices.esphome.io/devices/shelly-em-gen3/
# - https://community.home-assistant.io/t/shelly-em-gen3-solved/944171
# - https://kb.shelly.cloud/knowledge-base/shelly-em-gen3
#
# GPIOs:
#   GPIO0 - Dry-contact relay (normally open)
#   GPIO1 - Pushbutton
#   GPIO3 - ADC for NTC temperature sensor
#   GPIO4 - ADE7953 IRQ pin (active low)
#   GPIO5 - ADE7953 RESET pin (active low)
#   GPIO6 - I2C SCL
#   GPIO7 - I2C SDA
#   GPIO9 - Status LED (active low)
#   GPIO18 - Pin 1 of 7-pin header
#   GPIO20 - UART receive (U0RXD)
#   GPIO21 - UART transmit (U0TXD)
#
# I2C devices:
#  0x38 - ADE7953 Power Sensor
#  0x51 - AiP8563 Battery-backed real-time clock (not currently supported by ESPHome)


substitutions:
  # Set dual_sensors to false to remove the "B" and "Total" sensors
  dual_sensors: true


  # How often to update the power meter.
  update_interval: 20s


  # Calibrated on US-style 120V power with 50A current transformers.
  # You may need to calibrate this yourself if the numbers are inaccurate.
  calibration_voltage_gain: 0x32c78f
  calibration_current_gain_a: 0x490bb5
  calibration_current_gain_b: 0x498c15


esphome:
  name: "shelly-em-gen3"
  friendly_name: "Shelly EM Gen3"
  comment: "Shelly EM Gen3 - Smart wifi and bluetooth energy meter with dual current transformers"
  name_add_mac_suffix: true
  min_version: 2025.11.3    # for ade7953 bugfix #12180


esp32:
  variant: esp32c3
  flash_size: 8MB
  framework:
    type: esp-idf


# Enable logging
logger:
  level: DEBUG
  hardware_uart: uart0


# debug:


# Enable Home Assistant API with dynamic key
api:
  encryption:


ota:
  - platform: esphome
    id: ota_id
    # password: !secret ota_password


wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password
  # fast_connect: true
  enable_btm: true
  enable_rrm: true
  min_auth_mode: WPA2


  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    # password: !secret ap_password


captive_portal:


network:
  enable_ipv6: true


preferences:
  flash_write_interval: 5min


safe_mode:
  reboot_timeout: 10min


factory_reset:
  resets_required: 10
  max_delay: 10s
  on_increment:
    - logger.log:
        format: "(factory_reset) Fast power cycle count now %u, target %u"
        args: [x, target]


time:
  - platform: homeassistant
    id: homeassistant_time


button:
  - platform: factory_reset
    id: button_factory_reset
    name: Factory reset
    disabled_by_default: true


  - platform: restart
    id: button_restart
    name: Restart


  - platform: safe_mode
    id: button_safe_mode
    name: Safe Mode Boot


i2c:
  scl: GPIO6
  sda: GPIO7
  scan: true


esp32_ble_tracker:
  scan_parameters:
    active: false


bluetooth_proxy:
  active: false


light:
  - platform: status_led
    name: "Status LED"
    id: status_led_id
    disabled_by_default: true
    entity_category: diagnostic
    pin:
      number: GPIO9
      inverted: true
      ignore_strapping_warning: true


switch:
  # Dry-contact relay - normally open
  - platform: gpio
    name: Relay
    id: relay_id
    pin: GPIO0


sensor:
  - platform: uptime
    id: uptime_timestamp
    type: timestamp
    name: Last Boot


  - platform: wifi_signal # Reports the WiFi signal strength/RSSI in dB
    name: "WiFi Signal dB"
    id: wifi_signal_db
    update_interval: 60s


  - platform: copy # Reports the WiFi signal strength in %
    id: wifi_signal_percent
    source_id: wifi_signal_db
    name: "WiFi Signal Percent"
    filters:
      - lambda: return min(max(2 * (x + 100.0), 0.0), 100.0);
    unit_of_measurement: "Signal %"
    entity_category: diagnostic
    device_class: ""


  - platform: internal_temperature
    id: cpu_temperature
    name: "CPU Temperature"


  - platform: ntc
    id: ntc_temperature
    name: "NTC Temperature"
    entity_category: diagnostic
    unit_of_measurement: "°C"
    accuracy_decimals: 1
    icon: "mdi:thermometer"
    sensor: temp_resistance_reading
    calibration:
      b_constant: 3350
      reference_resistance: 10kOhm
      reference_temperature: 298.15K
  - platform: resistance
    id: temp_resistance_reading
    sensor: temp_analog_reading
    configuration: DOWNSTREAM
    resistor: 10kOhm
  - platform: adc
    id: temp_analog_reading
    pin: GPIO3
    attenuation: 12db


  # Note that on the Shelly EM Gen3, channels "A" and "B" are swapped between the chipset and the labels on the device.
  # The nIRQ pin of the ade7953 device seems to be connected to pin 9 (GPIO4)
  # of the ESP-Shelly-C38F.
  - platform: ade7953_i2c
    id: ade7953_id
    irq_pin: GPIO4
    update_interval: ${update_interval}
    use_accumulated_energy_registers: true


    voltage_gain: ${calibration_voltage_gain}
    current_gain_a: ${calibration_current_gain_a}
    current_gain_b: ${calibration_current_gain_b}


    voltage:
      id: line_voltage
      name: Voltage
    frequency:
      id: line_frequency
      name: Frequency
    current_b:
      id: current_a
      name: ${ "Current A" if dual_sensors else "Current" }
      accuracy_decimals: 3
    current_a:
      id: current_b
      name: Current B
      accuracy_decimals: 3
    power_factor_b:
      id: power_factor_a
      name: ${ "Power Factor A" if dual_sensors else "Power Factor" }
      filters:
        - multiply: -1
    power_factor_a:
      id: power_factor_b
      name: "Power Factor B"
      filters:
        - multiply: -1
    apparent_power_b:
      id: apparent_power_a
      name: ${ "Apparent Power A" if dual_sensors else "Apparent Power" }
    apparent_power_a:
      id: apparent_power_b
      name: "Apparent Power B"
    active_power_b:
      id: active_power_a
      name: ${ "Power A" if dual_sensors else "Power" }
    active_power_a:
      id: active_power_b
      name: "Power B"
    reactive_power_b:
      id: reactive_power_a
      name: ${ "Reactive Power A" if dual_sensors else "Reactive Power" }
      filters:
        - multiply: -1
    reactive_power_a:
      id: reactive_power_b
      name: "Reactive Power B"
      filters:
        - multiply: -1


  - platform: integration
    id: energy_a
    name: ${ "Energy A" if dual_sensors else "Energy" }
    sensor: active_power_a
    restore: false
    time_unit: h
    icon: mdi:meter-electric
    unit_of_measurement: "kWh"
    state_class: total_increasing
    device_class: energy
    accuracy_decimals: 3
    filters:
      - multiply: 0.001


  - platform: integration
    id: energy_b
    name: 'Energy B'
    sensor: active_power_b
    restore: false
    time_unit: h
    icon: mdi:meter-electric
    unit_of_measurement: "kWh"
    state_class: total_increasing
    device_class: energy
    accuracy_decimals: 3
    filters:
      - multiply: 0.001


  - platform: total_daily_energy
    id: daily_energy_consumed_a
    name: ${ "Daily Energy Consumed A" if dual_sensors else "Daily Energy Consumed" }
    power_id: active_power_a
    icon: "mdi:hours-24"
    unit_of_measurement: "kWh"
    state_class: total_increasing
    device_class: energy
    accuracy_decimals: 3
    filters:
      - multiply: 0.001


  - platform: total_daily_energy
    id: daily_energy_consumed_b
    name: "Daily Energy Consumed B"
    power_id: active_power_b
    icon: "mdi:hours-24"
    unit_of_measurement: "kWh"
    state_class: total_increasing
    device_class: energy
    accuracy_decimals: 3
    filters:
      - multiply: 0.001


  - platform: combination
    id: power_ab
    type: sum
    name: "Power Total"
    sources:
      - source: active_power_a
      - source: active_power_b
    device_class: power
    state_class: measurement


  - platform: combination
    id: energy_ab
    type: sum
    name: "Energy Total"
    sources:
      - source: energy_a
      - source: energy_b
    state_class: total_increasing
    accuracy_decimals: 3


  - platform: combination
    id: daily_energy_consumed_ab
    type: sum
    name: "Daily Energy Consumed Total"
    sources:
      - source: daily_energy_consumed_a
      - source: daily_energy_consumed_b
    state_class: total_increasing
    accuracy_decimals: 3


  - id: !remove ${ "active_power_b" if not dual_sensors else "" }
  - id: !remove ${ "apparent_power_b" if not dual_sensors else "" }
  - id: !remove ${ "current_b" if not dual_sensors else "" }
  - id: !remove ${ "daily_energy_consumed_b" if not dual_sensors else "" }
  - id: !remove ${ "daily_energy_consumed_ab" if not dual_sensors else "" }
  - id: !remove ${ "energy_ab" if not dual_sensors else "" }
  - id: !remove ${ "energy_b" if not dual_sensors else "" }
  - id: !remove ${ "power_ab" if not dual_sensors else "" }
  - id: !remove ${ "power_factor_b" if not dual_sensors else "" }
  - id: !remove ${ "reactive_power_b" if not dual_sensors else "" }


binary_sensor:
  - platform: gpio
    id: shelly_button_id
    name: "Button"
    entity_category: diagnostic
    pin:
      number: GPIO1
      inverted: true
      mode:
        input: true
        pullup: true
    filters:
      - settle: 10ms
    on_multi_click:
      - timing:
          - ON for at least 5s
        then:
          - logger.log: "Button held for 5s - Release for safe mode"
      - timing:
          - ON for at least 10s
        then:
          - logger.log: "Button held for 10s - Release for factory reset"
      - timing:
          - ON for 5s to 10s
          - OFF for at least 100ms
        then:
          - button.press: button_safe_mode
      - timing:
          - ON for at least 10s
          - OFF for at least 100ms
        then:
          - button.press: button_factory_reset


  - platform: gpio
    id: binary_sensor_header_gpio_id
    name: "Header GPIO"
    entity_category: diagnostic
    disabled_by_default: true
    pin:
      number: GPIO18
      inverted: true
      mode:
        input: true
        pullup: true

7-pin programming header

PCB pinout diagram

PinLabelDescriptionGPIO
1ESP_DBG_UARTGPIO18
2U0TXDconnect to serial RxD pinGPIO21
3U0RXDconnect to serial TxD pinGPIO20
4+3.3_ESPconnect to 3.3V power supply
5ENconnect to serial RTS pin
6GPIO0connect to serial DTR pinGPIO0
7GNDconnect to serial GND pin

Programming voltage: 3.3 V (LVTTL) Supply voltage: 3.3 V from external source Note: Whole PCB is live if connected to mains voltage. Programming pins are not isolated. Connect programming port to serial cable only if all other contacts are disconnected.

CT connector

Current transformer connector photo 1 Current transformer connector photo 2 Current transformer connector photo 3

TypeDescription
ManufacturerMolex
SeriesMicro-Fit 3.0 214755
Pitch3.0 mm
Number of Positions2
Number of Rows2

Photos

Package photos

Package front Package back Package left Package right Package top Package bottom

Device photos

Device top Device bottom Device terminals

PCB photos

PCB bottom

PCB top PCB left PCB front PCB right Voltage regulator

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