CH423 I/O Expander

The CH423 component allows you to use the CH423 I/O expander in ESPHome. It uses an I²C Bus for communication. The I²C address is not configurable as the CH423 has a separate address for each internal register.

Once configured, you can use any of the 24 available GPIO pins in many places a GPIO pin is required. Within ESPHome they can be used in place of internal GPIO pins in many of ESPHome’s components such as the GPIO Binary Sensor or GPIO Switch. They are not usable for PWM or other situations requiring an internal GPIO pin.

Pins 0-7 correspond to the bidirectional GPIO (IO0-IO7) pins on the CH423. Pins 8-23 correspond to the GPO (OC0-OC15) output-only pins.

# Example configuration entry
ch423:
  - id: ch423_hub

# Individual inputs
binary_sensor:
  - platform: gpio
    name: CH423 Input 0
    pin:
      ch423: ch423_hub
      number: 0
      mode: INPUT

# Individual outputs
switch:
  - platform: gpio
    name: CH423 Output 0
    pin:
      ch423: ch423_hub
      number: 8
      mode: OUTPUT

Configuration variables

id (Required, ID): The id to use for this ch423 component.

Pin configuration variables

ch423 (Required, ID): The id of the ch423 component of the pin.
number (Required, int): The pin number. Valid numbers are 0-23.
inverted (Optional, boolean): If the pin state should be inverted. Defaults to false.
mode (Optional, string): A pin mode to set the pin at. One of INPUT, OUTPUT, or OUTPUT_OPEN_DRAIN.

Pin mode restrictions

The CH423 has hardware limitations where certain settings apply globally:

Pins 0-7 (GPIO): Input is supported only on pins 0-7. All GPIO pins must be configured as input OR all as output - mixed configurations are not allowed due to the global IO_OE control bit.
Pins 8-23 (GPO): Output-only pins. Open drain mode is supported only on pins 8-23. All GPO pins must be configured as push-pull OR all as open-drain - mixed configurations are not allowed due to the global OD_EN control bit.

These restrictions are enforced at configuration validation time.