Pyserial and Arduino every Time new Connect problem

Question

I have a potentiometer and I want this to change the location of my cube. My script run is on the cube, connected to an "Always" actuator with True Toggle.

My problem is this line:

ser = serial.Serial('COM6',9600, timeout=1)

The script throws an error: ser is not defined

This line is read every Time, so my arduino must connect every Time. I need to perform a new connect every second, but I want float move.

So I try this, because the serial line is only executed once:

import serial
import time
import bge
import bpy

cont = bge.logic.getCurrentController()
ob = bpy.data.objects["Cube"]
scene = bge.logic.getCurrentScene().objects["Cube"]
own = cont.owner
PSerial=own['SerialVerbunden']

print (PSerial)
if (PSerial==False):
    ser = serial.Serial('COM6',9600, timeout=1)
    time.sleep(1)
    count = 0
    own['SerialVerbunden']=True




a = int(ser.readline().strip())
print (a)
count = count + 1
scene.worldPosition = [a, 0, 0]
ob.location = scene.worldPosition
ob.keyframe_insert(data_path="location", frame=count)

The script throws the error mentioned above: ser is not defined.

Yes this is true, because it is loading and at the end it forgets. The variable count have the same problem. It can't count. But how I can solve it? If I write a while loop, so I cant see my cube is moving, Blender freezes.

Answer 1

I strongly suggest you separate connecting from communication. Do not forget you should execute a closing when the connection is not needed anymore.

Basically you need this three operations in this order over multiple frames:

• establish a connection
• communicate (receive/send) via connection
• close connection [which seams not to apply at serial)

I suggest to implement it that way:

import serial
import bge

INTERNAL_PROPERTY_CONNECTION = "_connection"

listener = bge.logic.getCurrentController().owner

connection = listener.get(INTERNAL_PROPERTY_CONNECTION)
if not connection:
    connection = serial.Serial('COM6',9600, timeout=0)
    listener[INTERNAL_PROPERTY_CONNECTION] = connection

# your communciation
a = int(connection.readline().strip())
cube = bge.logic.getCurrentScene().objects["Cube"]
cube.worldPosition.x = a

Answer 2

Unfortunately I have no arduino to test with at the moment, but I did something quite similar in the past.

As you've discovered, time.sleep() will freeze the execution of the entire game engine, rather than just the script. Instead of sleeping or running in a loop (don't forget that the game engine is calling our script repeatedly anyway, so in a sense we're already in a loop), try something like this:

import serial

# the bge passes the current controller in as the first argument for us, we'll call it "cont"
def receive(cont): 
    # get current gameobject
    own = cont.owner

    # check for our "reminder property":
    if "ser_init" not in own: 
        # code in here is only run once
        ser = serial.Serial('/dev/ttyUSB0')
        # store a property to remind us later if we've already run the above code
        own["ser_init"] = True 

    # everything else will be executed every logic tic like normal:

    # get data (this is how I was reading in data for my project, you might do it differently)
    data = ser.readline().decode()
    # do something with data
    print(data)

I've put it in a function receive() so that it can be called by a module execution controller:

^{Note the .py extension on the script name. The script won't be executed without it!}

Answer 3

I have solved the problem by "gandalf3" Help. His script was not working, but showed me the function of modules, so that I could be solved it myself thank you! Monster Script also works, but the fault lay with me. Nevertheless, I did not understand his script. My mistake was in Monster script: The output was a huge delay. The Arduino had a too short delay "delay (1)". My Arduino was faster than Blender :) I changed it to "delay (25)". Now I can turn the potentiometer and without delay.

My Script works: This script runs in Module.

import serial


ser = serial.Serial('COM6',9600)

def funktion():
    print (ser.readline().decode())