anchor.diff:  configure_slot(spi2, disable_cs) -> configure(ss2, output_1);
   configure_slot(spi2, enable_cs)  -> configure(ss2, periph_c).
   
  -%% @doc Gets the given pins value
  +%% @doc Gets the value of a pin.
   %%
   %% === Example ===
   %% To see whether the red led of `led_1' is on use:
  
positive.code:     gen_server:start_link({local, ?MODULE}, ?MODULE, DriverMod, []).
  
  %% @equiv configure(Pin, Type, [default])
  configure(Pin, Type) -> configure(Pin, Type, [default]).
  
  %% @doc Configure pin type.
  %%
  %% @spec configure(Pin::pin(), Type::pin_type(), Attr) -> any()
  %%      Attr = [default]
  configure(Pin, Type, Attr) ->
      Command = <<(index(Pin)):8, 1:8, (map_type(Type)):8, (map_attr(Attr)):8>>,
      gen_server:call(?MODULE, {command, Command}).
  
  %% @doc Configure slot.
  %%
  %% @spec configure_slot(Slot::slot(), Config::Config) -> ok
  %%      Config = GPIO_Config | SPI_Config
  %%      GPIO_Config = {pin_type(), pin_type(), pin_type(), pin_type()}
  %%      SPI_Config = disable_cs | enable_cs
  configure_slot(gpio1, {T1, T2, T3, T4}) ->
      configure(gpio1_1, T1),
      configure(gpio1_2, T2),
  
negative.code: %% 1> grisp_gpio:clear(led1_r).
  %% <<>>
  %% '''
  - spec clear(pin()) -> any().
  clear(Pin) -> gen_server:call(?MODULE, {command, <<(index(Pin)):8, 3:8>>}).
  
  %% @doc Sets a pin to `true'.
  %%
  %% === Example ===
  %% Turn on the red led of `led_1' with:
  