gpio_rpi

v0.2.2

gpio_rpi v0.2.2 GpioRpi View Source

This is an Elixir interface to Raspberry PI GPIOs. Each GPIO is an independent GenServer.

Link to this section Summary

Types

int_direction()
pin_direction()
pullup_mode()

Functions

child_spec(arg)

Returns a specification to start this module under a supervisor

init(list)

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

read(pid)

Read the current value of the pin

release(pid)

Free the resources associated with pin and stop the GenServer

set_direction(pid, pin_direction, opts \\ [])

Set the input/output direction of the pin. Additionally allows setting :mode and `:interrupt’

set_int(pid, direction)

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

set_mode(pid, pullup_mode)

Changes the pullup register to :none, :down, or :up

start_link(pin, pin_direction, opts \\ [])

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. Optional parameters: :mode set pullup register, see set_mode/2. :interrupt, enable interrupts, see set_int/2 for the different transitions

write(pid, value)

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

Link to this section Types

Link to this type int_direction() View Source 
int_direction() :: :rising | :falling | :both
Link to this type pin_direction() View Source 
pin_direction() :: :input | :output
Link to this type pullup_mode() View Source 
pullup_mode() :: :none | :down | :up

Link to this section Functions

Link to this function child_spec(arg) View Source

Returns a specification to start this module under a supervisor.

See Supervisor.

Link to this function init(list) View Source

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 :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 (re)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.

Link to this function read(pid) View Source 
read(pid()) :: :ok | {:error, term()}

Read the current value of the pin.

Link to this function release(pid) View Source 
release(pid()) :: :ok

Free the resources associated with pin and stop the GenServer.

Link to this function set_direction(pid, pin_direction, opts \\ []) View Source 
set_direction(pid(), pin_direction(), [term()]) :: :ok | {:error, term()}

Set the input/output direction of the pin. Additionally allows setting :mode and `:interrupt’

Link to this function set_int(pid, direction) View Source 
set_int(pid(), int_direction()) :: :ok | {:error, term()}

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.

Link to this function set_mode(pid, pullup_mode) View Source 
set_mode(pid(), pullup_mode()) :: :ok | {:error, term()}

Changes the pullup register to :none, :down, or :up.

Link to this function start_link(pin, pin_direction, opts \\ []) View Source 
start_link(integer(), pin_direction(), [term()]) :: {:ok, pid()}

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. Optional parameters: :mode set pullup register, see set_mode/2. :interrupt, enable interrupts, see set_int/2 for the different transitions.

Link to this function write(pid, value) View Source 
write(pid(), 0 | 1 | true | false) :: :ok | {:error, term()}

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.