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ESPHome - Smart Home Made Simple 2026.4.0

TCA9555 I/O Expander

The TCA9555 component allows you to use TCA955 I/O expanders (datasheet) in ESPHome. It uses I²C Bus for communication.

Once configured, you can use any of the 16 pins (TCA9555) as pins for your projects. Within ESPHome they emulate a real internal GPIO pin and can therefore be used with many of ESPHome’s components such as the GPIO binary sensor or GPIO switch.

Any option accepting a Pin Schema can theoretically be used, but some more complicated components that do communication through this I/O expander will not work.

# Example configuration entry
tca9555:
  - id: 'tca9555_hub'
    interrupt_pin: GPIOXX


# Individual outputs
switch:
  - platform: gpio
    name: "TCA9555 Pin #0"
    pin:
      tca9555: tca9555_hub
      # Use pin number 0
      number: 0

Configuration variables

Section titled “Configuration variables”
  • id (Required, ID): The id to use for this TCA9555 component.
  • address (Optional, int): The I²C address of the driver. Defaults to 0x21.
  • interrupt_pin (Optional, Pin Schema): The pin connected to the INT output of the TCA9555. When configured, the component becomes interrupt-driven instead of polling — it only reads the chip when a pin actually changes state, significantly reducing I²C bus traffic and CPU usage. The INT pin is active-low and open-drain, so an external or internal pull-up resistor is required. Must be an internal GPIO pin (not another expander pin).

Pin configuration variables

Section titled “Pin configuration variables”

  • TCA9555 (Required, ID): The id of the TCA9555 component of the pin.

  • number (Required, int): The pin number.

  • inverted (Optional, boolean): If all read and written values should be treated as inverted. Defaults to false.

  • mode (Optional, string): A pin mode to set for the pin at. One of INPUT or OUTPUT.

See Also

Section titled “See Also”