Background:
I was given a task for college to implement an elevator's source code for an Arduino UNO with a user interface shield that contains: a 7-Segment display and a total of 8 buttons, one for each floor plus two to control the doors. The floor buttons also have an LED.
The hardware is only for human user input, but the brains is made entirely within Erlang. Before we got to implement this project in hardware, we used a simulation that uses wxWidgets to display the following UI: a window that displays the elevator doors, 6 more windows for each floor, and a window for the internal button array of the elevator. This button array is what I'm trying to implement within an Arduino.
Some code:
Our teacher gave us some confusing notes about the use of erlang:open_port/2 that I can't understand yet. The testing code we're using is the following:
-module(proUSB).
-export([start/1, order/2, loop/1, exit/2]).
start(Port_alias) ->
Port = open_port(Port_alias, []),
Pid = spawn(proUSB, loop, [Port]),
port_connect(Port, Pid),
{Port,Pid}.
order(Port,Value) ->
port_command(Port,Value).
loop(P) ->
receive
{P,{data,A}} ->
io:format("Received: ~p~n", [A]),
loop(P);
{'EXIT',P,_Reason} ->
port_close(P),
io:format("Unexpected finalization~n",[]);
exit ->
io:format("Proces finalization~n",[]);
Other -> io:format("Fi ~p~n",[Other])
end.
exit(Pid, Port) ->
port_close(Port),
Pid!exit.
As I've understood and successfully tested in Windows Subsystem for Linux (WSL) with the code mentioned above, all I have to execute in the Erlang shell is
> {Port, Pid} = proUSB:start("/dev/ttyS6").
{#Port<0.7>,<0.82.0>}
This will open the port. I can now send orders to the Arduino USART in the protocol we've designed. To light up the number three in the 7-segment display, we write
> proUSB:order(Port,"D3").
true
Now, if we press the floor button 1, you can see in the terminal
Received: "B1\n"
Received: "\n"
Received: "B1\n"
Received: "\n"
My question:
If I want to use Windows Powershell to do the same connection to the serial port, my teacher told us to write "COM6" instead of "/dev/ttyS6", but as I have tested, I can't get a connection but I get this error
> {Port, Pid} = proUSB:start("COM6").
** exception exit: einval
>
What am I missing? If WSL works with "/dev/ttyS6", why shouldn't it work with Windows when I can use the serial port with "RealTerm: Serial Capture Program"?
