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PCA9505 I/O Expander

The PCA9505 component lets you use the NXP PCA9505 and PCA9506 I/O expanders in ESPHome using the I²C Bus for communication. Both chips provide 40 I/O pins and share the same command interface, so either can be used with this component.

Once configured, the 40 pins can be used anywhere ESPHome accepts a Pin Schema. Within ESPHome they behave like internal GPIO pins, so they work with components such as the GPIO binary sensor and the GPIO switch.

NOTE

The pins are numbered 0 to 39. The chip groups them into five ports of eight: pins 0-7 are port 0, pins 8-15 are port 1, and so on up to pins 32-39 on port 4. ESPHome hides this grouping, so you only ever refer to a pin by its number.

The 7 bit I²C device address ranges from 0x20 to 0x27, selected by the three address pins. Up to eight of these devices can therefore share one I²C bus. Refer to the datasheet linked below for the address pin wiring.

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
pca9505:
  - id: 'pca9505_device'
    interrupt_pin: GPIOXX


# Individual output
switch:
  - platform: gpio
    name: "PCA9505 Pin #0"
    pin:
      pca9505: pca9505_device
      number: 0
      mode:
        output: true


# Individual input
binary_sensor:
  - platform: gpio
    name: "PCA9505 Pin #39"
    pin:
      pca9505: pca9505_device
      number: 39
      mode:
        input: true

Configuration Variables

Section titled “Configuration Variables”
  • id (Required, ID): The id to use for this pca9505 component.
  • address (Optional, int): The I²C address of the expander. Defaults to 0x20.
  • interrupt_pin (Optional, Pin Schema): The pin connected to the INT output of the expander. When configured, the component only reads the chip after a pin actually changes, instead of polling it on every loop, which cuts I²C traffic considerably. INT is active low and open drain, so a pull-up resistor is required. Must be an internal GPIO pin, not another expander pin.

Pin Configuration Variables

Section titled “Pin Configuration Variables”
  • pca9505 (Required, ID): The id of the pca9505 component of the pin.
  • number (Required, int): The pin number, 0 to 39.
  • 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. One of INPUT or OUTPUT.

See Also

Section titled “See Also”