Pybricks project with bluetooth Xbox Controller

[GhoulFool]

Not a coder but I thought I'd have a go a Pybricks.

Following the instructions for this project when i run the minipython code, one of the motors runs for a about 10 seconds (B, I think). Not sure if that's supposed to happen without any input from the xbox controller - and then I get the error:
File "test_controller.py", line 15, in
RuntimeError: The steering mechanism has no end stop. Did you build a car yet?

The answer is no, I'm testing the control system first, so there's no physical stopper for the steering motor. Car still in pieces.

However, I thought I'd just test the controls and se if that is working with:

from pybricks.hubs import TechnicHub
from pybricks.iodevices import XboxController
from pybricks.tools import wait

hub = TechnicHub()

print("Controller...")


# Initialize the Xbox controller
xbox = XboxController()

while True:
    # Read all relevant inputs
    left_joystick = xbox.joystick_left()
    right_joystick = xbox.joystick_right()
    triggers = xbox.triggers()
    button_a = xbox.button_a()
    button_b = xbox.button_b()
    button_x = xbox.button_x()
    button_y = xbox.button_y()

    # Print the inputs
    print("Left joystick:", left_joystick)
    print("Right joystick:", right_joystick)
    print("Triggers:", triggers)
    print("Button A:", button_a)
    print("Button B:", button_b)
    print("Button X:", button_x)
    print("Button Y:", button_y)

    wait(200)  # Wait for 200 ms 

However, that doesn't print out anything when using the controller, but is responsive and works well when testing it on https://gamepadscan.com/game-pad-tester/

Any ideas where I'm going wrong?

[laurensvalk]

There should be a message saying that the hub will disconnect from the PC to make way for the connection to the Xbox Controller.

So, there won't be any printed output. Instead, maybe you could turn lights on in different colors for different buttons?

Or you can use the original example and just block the steering motor by hand after a while as "end stops".

[Sirus-7]

The first time you use a controller with a hub, you will need to pair them.

https://docs.pybricks.com/en/latest/iodevices/xboxcontroller.html#xbox-controller-pairing-instructions

[laurensvalk]

See this answer above on why that happens.

[GhoulFool]

This has become increasingly more and more frustrating for something that's mean to be a bit of fun.

I've tried to change the code to change the lights (no idea if that works or not)

Without any meaningful feedback as where, when and why things aren't working as they should, everything is a shot in a the dark:

from pybricks.hubs import TechnicHub
from pybricks.iodevices import XboxController
from pybricks.parameters import Color
from pybricks.tools import wait

hub = TechnicHub()
xbox = XboxController()

while True:
  if xbox.button_a():
    # Change hub color to red
    hub.light.on(Color.RED)
    print("Red light")
  elif xbox.button_b():
    # Change hub color to blue
    hub.light.on(Color.ORANGE)
    print("Blue light")
  else:
    # Optional: turn off lights when no button pressed
    hub.light.off()

  wait(200)

(code formatting refused to work properly)

[laurensvalk]

Very close. Try the following. Using block code might help you discover the syntax too:

Remember to put the controller in pairing mode and then just start this. Once connected, this example makes the light turn yellow:

from pybricks.hubs import TechnicHub
from pybricks.iodevices import XboxController
from pybricks.parameters import Color, Button
from pybricks.tools import wait

hub = TechnicHub()
xbox = XboxController()

while True:
  if Button.A in xbox.buttons.pressed():
    # Change hub color to red
    hub.light.on(Color.RED)
    print("Red light")
  elif Button.B in xbox.buttons.pressed():
    # Change hub color to blue
    hub.light.on(Color.BLUE)
    print("Blue light")
  else:
    # Optional: turn lights yellow when no button pressed
    hub.light.on(Color.YELLOW)

[BertLindeman]

Do you have access to an android tablet you can use with pybricks code?

On android you can debug problems with xbox controller easier as android allows a bluetooth connection to the xboxcontroller and keep the interface to the webpage active.

Change this source line on Android

xbox = XboxController()

into

xbox = XboxController(stay_connected=True)

And if there are errors in your program you can still see the traceback.
Also print output is shown.

You can debug on android and after the program is working OK, copy it back to the PC.
And on the PC switch back to:

xbox = XboxController()

or

xbox = XboxController(stay_connected=False)

[GhoulFool]

I tried this but the CSS and lack of being able to paste the code into mobile Chrome is prohibitive.

[GhoulFool]

I don't think the Xbox controller is pairing correctly. I've tried pairing and unpairing with Windows in order to reset it but no joy:

I ran a very simple program in order to initialise pairing:
from pybricks.iodevices import XboxController from pybricks.parameters import Direction, Port from pybricks.pupdevices import Motor from pybricks.robotics import Car from pybricks.tools import wait print("Init...")

Which printed out "Init..." but the light on the Xbox controller continues to flash - which I take to mean it hasn't paired correctly.
In running the program I do geta Windows pop up asking to pair the controller with Windows - which I'm assuming I ignore.

Apart from re-setting everything with a very large sledge hammer, any other suggestions?

[GhoulFool]

Sorry about the confusion, I've tried the car code, as well as the (corrected) lights, and a minimal version just in case the While loop was causing problems. Still to no avail. The lights code didn't work - in that pressing the controller buttons didn't change the hub light, which remained to pulse blue-ish whilst the code was running.

Also tried to simulate end points by holding the axle in motor as it rotates- but the torque on those things is quite powerful. - which is why I was looking to create a minimal bit of code to pair the controllers - but as I type I don't think that's quite how it works. - in the the same bit of code needs to run once to pair and than again without pairing.

[laurensvalk]

When you tried this example, did you hold the pair button in the back to make the white light blinking fast? Do that before starting the program.

As for the steering -- anything that prevents the motor from spinning endlessly will do. For example, this will spin the red beam to both ends of the green beam and then finds the center:

[GhoulFool]

I've constructed something similar but to the same effect - so the code is talking to Lego fine... but not to the controller

Hmmm - So after a bit of searching I decided to update the Xbox Controller firmware via USB to the Xbox - Bada bing! Whaddya know? the code works fine, just like in the video

Thank you all for your help!

[laurensvalk]

Glad to hear you got it working!

[Sirus-7]

Hi Laurens, you are a really good teacher. I admire your patience. 😄