@spec blink(keyword()) :: :ok

Starts or updates regular blinking for the LED.

Accepts keyword options:

• :name – GenServer name of the LED. Defaults to the module name.
• :interval – (integer) Blink interval in milliseconds. Default is 250 (≈2 Hz).
• :times – (integer) Number of blinks. Default is -1 for continuous blinking.

This will cancel any existing blinking or repeat timers before starting.

Use repeat/1 instead for experimental or overlapping blink patterns.

Examples

iex> LED.blink()
:ok

iex> LED.blink(name: :green_led, interval: 500, times: 10)
:ok

@spec cancel_timers(atom() | pid() | {atom(), any()} | {:via, atom(), any()}) :: :ok

Cancels all active timers associated with the LED process.

This stops any ongoing blink/1 or repeat/1 patterns by clearing all stored timer_refs. Use this to reset the LED's timing behavior before issuing new commands.

name – (optional) the GenServer name of the LED; defaults to the module.

Examples

iex> LED.cancel_timers()

iex> LED.cancel_timers(:led_green)

Returns a specification to start this module under a supervisor.

See Supervisor.

@spec is_lit?(atom() | pid() | {:global, any()} | {:via, atom(), any()}) :: boolean()

Returns true if the LED is currently on (state == 1), otherwise returns false.

Accepts an optional name argument for the GenServer process name set via start_link/1. Defaults to the module name.

Examples

iex> {:ok, _pid} = LED.start_link()
iex> LED.on()
iex> LED.is_lit?()
true
iex> LED.off()
iex> LED.is_lit?()
false

iex> {:ok, _pid} = LED.start_link(gpio_pin: 23, name: :led_pink)
iex> LED.on(:led_pink)
iex> LED.is_lit?(:led_pink)
true
iex> LED.off(:led_pink)
iex> LED.is_lit?(:led_pink)
false

@spec lit?(atom() | pid() | {:global, any()} | {:via, atom(), any()}) :: boolean()

Returns true if the LED is currently on (state == 1), otherwise returns false.

Accepts an optional name argument for the GenServer process name set via start_link/1. Defaults to the module name.

Examples

iex> {:ok, _pid} = LED.start_link()
iex> LED.on()
iex> LED.lit?()
true
iex> LED.off()
iex> LED.lit?()
false

iex> {:ok, _pid} = LED.start_link(gpio_pin: 23, name: :led_pink)
iex> LED.on(:led_pink)
iex> LED.lit?(:led_pink)
true
iex> LED.off(:led_pink)
iex> LED.lit?(:led_pink)
false

@spec off(atom() | pid() | {atom(), any()} | {:via, atom(), any()}) :: :ok

Turns the LED off by setting its GPIO state to 0.

Accepts an optional name argument to control a specific LED process started with start_link/1. If no name is given, the default module name is used.

Calling this will cancel any active blinking or repeat timers before switching the LED off.

Examples

Turn off the default LED (GPIO pin 22):

iex> LED.off()

Start and turn off a named LED on GPIO pin 23:

iex> {:ok, _pid} = LED.start_link(gpio_pin: 23, name: :led_yellow)
iex> LED.off(:led_yellow)

@spec on(atom() | pid() | {atom(), any()} | {:via, atom(), any()}) :: :ok

Turns the LED on by setting its GPIO state to 1.

Accepts an optional name argument to control a specific LED process started with start_link/1. If no name is given, the default module name is used.

Calling this will cancel any active blinking or repeat timers before switching the LED on.

Examples

Turn on the default LED (GPIO pin 22):

iex> LED.on()

Start and turn on a named LED on GPIO pin 23:

iex> {:ok, _pid} = LED.start_link(gpio_pin: 23, name: :led_green)
iex> LED.on(:led_green)

@spec repeat(keyword()) :: :ok

Starts a repeating blink pattern on the LED.

Unlike blink/1, this function allows multiple overlapping patterns, enabling experimental or polyrhythmic effects. Each call creates a new timer without cancelling existing ones.

Can be manually canceled using cancel_timers/1.

Useful for creative setups or layered visual rhythms. For best visibility, use intervals greater than 10ms.

Options

• :name – GenServer name of the LED. Defaults to the module name.
• :interval – (integer) Interval in milliseconds between toggles. Default: 250 (≈2 Hz).
• :times – (integer) Number of blinks. -1 means infinite. Default: -1.

If you want predictable, single-pattern blinking, use blink/1 instead.

Examples

iex> LED.repeat()
:ok
iex> LED.repeat(interval: 969)
:ok
iex> LED.cancel_timers()

iex> LED.repeat(name: :green_led, interval: 900)
:ok
iex> LED.repeat(name: :green_led, interval: 690)
:ok
iex> LED.cancel_timers(:green_led)

@spec set(any(), atom() | pid() | {atom(), any()} | {:via, atom(), any()}) :: :ok

Sets the LED to a specific state: 1 for on, 0 for off.

Any active blinking or repeat timers will be canceled before setting the state, ensuring full manual control.

Accepts an optional name argument to target a specific LED GenServer. If omitted, it uses the default module name.

Examples

Turn off and on the default LED:

iex> LED.set(0)
iex> LED.set(1)

Control a named LED:

iex> {:ok, _pid} = LED.start_link(gpio_pin: 23, name: :led_red)
iex> LED.set(0, :led_red)
iex> LED.set(1, :led_red)

@spec start_link(keyword()) :: :ignore | {:error, any()} | {:ok, pid()}

Starts the LED GenServer.

Accepts keyword arguments in init_args to configure the LED:

• :name – Optional name for the GenServer (used for referencing multiple LEDs)
• :gpio_pin – (integer) GPIO pin to control; defaults to 22
• :initial_value – (0 or 1) Initial LED state; 0 = off, 1 = on (default: 1)

Examples

Start the default LED:

iex> {:ok, _pid} = LED.start_link()

Start a named LED on pin 23, initially off. You can control it with:

iex> {:ok, _pid} = LED.start_link(name: :green_led, gpio_pin: 23, initial_value: 0)
iex> LED.on(:green_led)
iex> LED.is_lit?(:green_led)
true

@spec timer_start(
  integer(),
  integer(),
  atom() | pid() | {atom(), any()} | {:via, atom(), any()}
) :: :ok

Starts a blinking timer that toggles the LED at a given interval and for a given number of times.

• interval – blinking interval in milliseconds.
• times – how often to toggle the LED. Use -1 for infinite blinking.

Use cancel_timers/1 to stop the blinking manually.

Examples

Blink the default LED continuously every 200ms:

iex> LED.timer_start(200, -1)

Blink a named LED 5 times every 300ms:

iex> LED.timer_start(300, 5, :led_blue)

@spec toggle(atom() | pid() | {:global, any()} | {:via, atom(), any()}) :: :ok

Toggles the LED: turns it off if on, and on if off.

Examples

iex> {:ok, _pid} = LED.start_link()
iex> LED.on()
iex> LED.toggle()
iex> LED.is_lit?()
false

iex> {:ok, _pid} = LED.start_link(gpio_pin: 23, name: :green_led)
iex> LED.off(:green_led)
iex> LED.toggle(:green_led)
iex> LED.is_lit?(:green_led)
true