non original lego motor not working, but works in mindstorms app. How to fix issue?

[butch01]

Hi, have 51515 robot inventor set and i am using pybricks with python.

I ordered two non original motors from aliexpress -> these ones: https://de.aliexpress.com/item/1005008784855541.html

The motors are working fine with lego's mindstorms app when using the lego firmware on the hub. Reading absolute positioning, driving the motor at different speeds, etc... just working fine with lego app and original lego firmware.

But when I use pybricks on my hub, these replacement motors don't work. The code seems to stop at initializing the motor object.
before motor init is logged, but nothing more.

Here is my code:

from pybricks.hubs import InventorHub
from pybricks.pupdevices import Motor, ColorSensor, UltrasonicSensor
from pybricks.parameters import Button, Color, Direction, Port, Side, Stop
from pybricks.robotics import DriveBase
from pybricks.tools import wait, StopWatch
from pybricks.parameters import Color, Axis
from uerrno import ENODEV, EBUSY, EINVAL, EIO, EAGAIN

hub = InventorHub(top_side=Axis.Z, front_side=Axis.Y)
stopWatch = StopWatch()

print("before motor init")

try:
    motorA = Motor(Port.A)
    print("motor initialized.")
except Exception as ex:
    print(f"error: {ex}")

# motorB = Motor(Port.A)
print("after motor init")

print("starting")
while True:
    print(f"A: {motorA.angle()}")
    wait(500)

The code works fine with an original lego motor, but not with the replacement.

Any Idea how to debug the issue and fix it?

[dlech]

Any Idea how to debug the issue and fix it?

The best way I have found to do this is to use a logic analyzer to see what pins 5 and 6 are doing. Then you can compare what the official LEGO software does compared to Pybricks.

However, I don't think we are going to go out of our way to support knock-off LEGO motors. We don't want The LEGO Group to have a reason to be unhappy with what we are doing here! At the same time, this is free and open source software, so you are free to do what you like with it if you want to reverse engineer it and make your own firmware to fix it.

[Eggmanplant]

Any Idea how to debug the issue and fix it?

The best way I have found to do this is to use a logic analyzer to see what pins 5 and 6 are doing. Then you can compare what the official LEGO software does compared to Pybricks.

However, I don't think we are going to go out of our way to support knock-off LEGO motors. We don't want The LEGO Group to have a reason to be unhappy with what we are doing here! At the same time, this is free and open source software, so you are free to do what you like with it if you want to reverse engineer it and make your own firmware to fix it.

Yup. Supporting knockoffs isn't elegant.