Returns a specification to start this module under a supervisor.

See Supervisor.

Invoked when the server is started. start_link/3 or start/3 will block until it returns.

args is the argument term (second argument) passed to start_link/3.

Returning {:ok, state} will cause start_link/3 to return {:ok, pid} and the process to enter its loop.

Returning {:ok, state, timeout} is similar to {:ok, state} except handle_info(:timeout, state) will be called after timeout milliseconds if no messages are received within the timeout.

Returning {:ok, state, :hibernate} is similar to {:ok, state} except the process is hibernated before entering the loop. See c:handle_call/3 for more information on hibernation.

Returning {:ok, state, {:continue, continue}} is similar to {:ok, state} except that immediately after entering the loop the c:handle_continue/2 callback will be invoked with the value continue as first argument.

Returning :ignore will cause start_link/3 to return :ignore and the process will exit normally without entering the loop or calling c:terminate/2. If used when part of a supervision tree the parent supervisor will not fail to start nor immediately try to restart the GenServer. The remainder of the supervision tree will be started and so the GenServer should not be required by other processes. It can be started later with Supervisor.restart_child/2 as the child specification is saved in the parent supervisor. The main use cases for this are:

• The GenServer is disabled by configuration but might be enabled later.
• An error occurred and it will be handled by a different mechanism than the Supervisor. Likely this approach involves calling Supervisor.restart_child/2 after a delay to attempt a restart.

Returning {:stop, reason} will cause start_link/3 to return {:error, reason} and the process to exit with reason reason without entering the loop or calling c:terminate/2.

Callback implementation for GenServer.init/1.

Helper method for reading the pin number that the GPIO GenServer is linked to.

Read the current value of the pin.

Free the resources associated with pin and stop the GenServer.

Turn on “interrupts” on the input pin. The pin can be monitored for :rising transitions, :falling transitions, or :both. The process that calls this method will receive the messages.

Start and link a new GPIO GenServer. pin should be a valid GPIO pin number on the system and pin_direction should be :input or :output.

Including :start_value in opts will explicitly write the GPIO value on start. Expected values are 1, 0, true, or false

ElixirALE.GPIO.start_link(16, :output, start_value: 1)

Write the specified value to the GPIO. The GPIO should be configured as an output. Valid values are 0 or false for logic low and 1 or true for logic high. Other non-zero values will result in logic high being output.