@callback backend_info() :: map()

Return information about this backend

@callback enumerate(options :: Circuits.GPIO.open_options()) :: [
  Circuits.GPIO.identifiers()
]

Return a list of GPIOs

See t:GPIO.identifiers/0 for the information that is returned. The options contain backend-specific options to help with enumeration.

@callback force_close(
  gpio_spec :: Circuits.GPIO.gpio_spec(),
  options :: Circuits.GPIO.open_options()
) :: :ok | {:error, atom()}

Force all open handles that reference a GPIO spec to close

@callback identifiers(
  gpio_spec :: Circuits.GPIO.gpio_spec(),
  options :: Circuits.GPIO.open_options()
) :: {:ok, Circuits.GPIO.identifiers()} | {:error, atom()}

Return identifying information about a GPIO

See t:gpio_spec/0 for the ways of referring to GPIOs. The options contain backend-specific options to help enumerating GPIOs.

If the GPIO is found, this function returns identifying information about the GPIO.

@callback open(
  gpio_spec :: Circuits.GPIO.gpio_spec() | [Circuits.GPIO.gpio_spec()],
  direction :: Circuits.GPIO.direction(),
  options :: Circuits.GPIO.open_options()
) :: {:ok, Circuits.GPIO.Handle.t()} | {:error, atom()}

Open one or more GPIOs

See t:gpio_spec/0 for the ways of referring to GPIOs. Set direction to either :input or :output. If opening as an output, then be sure to set the :initial_value option to minimize the time the GPIO is in the default state.

Passing a list of GPIO specs opens them together as a group. read/1 then returns a single integer and write/2 takes one, with the first spec as the least significant bit. All GPIOs in a group must be on the same controller.

Options:

• :initial_value - Set to 0 or 1 (or an integer with one bit per line for a group). Only used for outputs. Defaults to 0.
• :pull_mode - Set to :not_set, :pullup, :pulldown, or :none for an input pin. :not_set is the default.
• :drive_mode - Set to :push_pull, :open_drain, or :open_source. :push_pull is the default.

Returns {:ok, handle} on success.

@callback status(
  gpio_spec :: Circuits.GPIO.gpio_spec(),
  options :: Circuits.GPIO.open_options()
) :: {:ok, Circuits.GPIO.status()} | {:error, atom()}

Return a GPIO's current status

This function returns how a GPIO is configured. The GPIO doesn't need to be opened. It's different from gpio_identifiers/2 since it returns dynamic information whereas gpio_identifiers/2 only returns information about how to refer to a GPIO and where it exists in the system.

See t:gpio_spec/0 for the ways of referring to GPIOs. The options contain backend-specific options to help enumerating GPIOs.

If the GPIO is found, this function returns its status.