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fsm.erl
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fsm.erl
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-module(fsm).
-export([start/0]).
% Finite state machine, that keeps control over the state of the elevator.
% Does some interfacing with driver, such as checking if the correct destination
% is reached, and stopping motor direction thereafter.
start() ->
st_init().
st_init() ->
io:format("fsm: initializing ~n"),
driver:set_motor_direction(driver, down),
receive
{ev_floor_reached, 0} ->
io:format("fsm: elevator initialized, behold my initial glory ~n"),
driver:set_motor_direction(driver, stop),
st_idle();
_Other ->
st_init()
after 10000 ->
io:format("fsm: init timed out, trying again ~n"),
st_init()
end.
st_idle() ->
worldview ! {state, idle},
receive
{ev_new_order} ->
st_moving();
{no_orders} ->
st_idle();
_Other ->
st_idle()
end.
st_moving() ->
io:format("fsm: moving ~n"),
worldview ! {state, moving},
worldview ! {request, direction, fsm},
receive {response, direction, Direction} -> ok end,
driver:set_motor_direction(driver, Direction),
worldview ! {direction, Direction},
worldview ! {request, wv, fsm},
receive {response, wv, WorldView} -> ok end,
[Dest|_] = element(4, WorldView),
DestFloor = element(1, Dest),
case Direction == stop of
true -> fsm ! {ev_floor_reached, DestFloor};
false -> ok
end,
receive
{ev_floor_reached, Floor} ->
case DestFloor == Floor of
true ->
io:format("fsm: destination reached ~n"),
driver:set_motor_direction(driver, stop),
worldview ! {direction, stop},
order_manager ! {remove, Floor},
st_doors_open();
false ->
st_moving()
end;
_Other ->
st_moving()
end.
st_doors_open() ->
io:format("fsm: doors opened ~n"),
worldview ! {state, doors_open},
driver:set_door_open_light(driver, on),
receive
after 2000 ->
driver:set_door_open_light(driver, off),
order_manager ! {request_new_order},
receive
{ev_new_order} ->
st_moving();
{no_orders} ->
st_idle()
end
end.