anchor.diff:  pin(mag) -> spi1_pin9;
   pin(alt) -> spi1_pin10.
   
  +%% @doc Get the registers (with the possible entries) of all components.
  +%% @spec registers() -> Map
   registers() ->
       #{
           acc => registers(acc),
  
positive.code: %
  % LPS25HB digital barometer
  % http://www.st.com/web/en/resource/technical/document/datasheet/DM00141379.pdf
  -module(pmod_nav).
  
  -behavior(gen_server).
  
negative.code:         alt => registers(alt)
      }.
  
  %% @doc Get the registers (with the possible entries) of one component.
  %%
  %% === Example ===
  %% To see the possible configurations in `ctrl_reg1_g' use:
  %% ```
  %% 4> maps:find(ctrl_reg1_g, pmod_nav:registers(acc)).
  %% {ok,{16,read_write,1,
  %%      [{odr_g,3,
  %%              #{power_down => 0,
  %%                {hz,119} => 3,
  %%                {hz,238} => 4,
  %%                {hz,476} => 5,
  %%                {hz,952} => 6,
  %%                {hz,14.9} => 1,
  %%                {hz,59.5} => 2}},
  %%       {fs_g,2,#{{dps,245} => 0,{dps,500} => 1,{dps,2000} => 3}},
  %%       {0,1},
  %%       {bw_g,2,raw}]}}
  %% '''
  %%
  %% @spec registers(Comp) -> Map
  %%        Comp = acc | mag | alt
  registers(acc) ->
      #{
          act_ths => {16#04, read_write, 1, [
  