line_follower.exs

defmodule LineFollower do
  using Time.PLC
  
  # These may be extracted to a separate module
  # input and output are macros that generate something lacced 'optical' and 'pwm'
  # that somehow link to the signal 'objects'. Think Ruby 'attr' function
  # the physical addresses are linked to the actual hardware being used
  input :optical, "I3.0", desc: "Optical line sensor"
  output :pwm, "PIW100", desc: "Steering motor PWM input"
  
  signal :tmp do
    input |> time_on(~t"100 ms") |> time_off(~t"100 ms")
  end
  # at this point tmp is a discrete signal 'object'
  
  freeze do
    # at this point tmp represents the instantaneous value of the tmp signal
    pwm_output = case tmp do
      true ->
        100.0
      _ ->
        -100.0
    end
  end
  
  # at this point, pwm_output is converted from instantaneous value to a signal 'object'
  pwm_output |> assign_to pwm
end