[Question] Any way to run version 3.0+ on the EV3?

[Nawor3565]

Question I can't seem to find a clear answer as to whether there's any version of Pybricks past version 2.0.0 that works with the Mindstorm EV3. It seems like SD card images only exist for V2, so I would assume that support for the EV3 was dropped passed that release, but I would like to make sure.

Context I tried to use the driver.curve() function on my EV3, only to get an error AttributeError: 'DriveBase' object has no attribute 'curve'. It appears that the function was added at some point in version 3, and since it would make my code far easier to write, I was hoping I could update the Pybricks software that came with my Mindstorms brick.

[dlech]

Please see https://github.com/pybricks/support/discussions/370#discussioncomment-885240 for the answer.

[Nawor3565]

Thanks! I tried what the comment said but it didnt seem to work. I tried placing the pybricks-micropython file in the specified directory both on the micro-SD card and on the Mindstorm itself via SSH/SFTP (rebooting afterwards both times), but the curve() function still doesn't exist so I assume the update didn't work. Any idea what I might be doing wrong?

[Lemru]

The link in #370 (comment) doesn't seem to be available anymore. Where could I download the latest build instead?

Thanks in advance for your support!

[dlech]

This link will always give the "latest" builds: https://github.com/pybricks/pybricks-micropython/actions/workflows/build.yml?query=is%3Asuccess+branch%3Amaster

Click on the first one in the list the scroll down to Artifacts and click pybricks-micropython to download the file.

[Lemru]

Found it! Thanks for the explanation. Would it be necessary to update the files in /usr/lib/pybricks-micropython/ as well? If so, where would I find them?

[dlech]

Would it be necessary to update the files in /usr/lib/pybricks-micropython/ as well?

No, there is nothing to update here.

[Lemru]

Thanks for spending your time on this. I raised the question, because I get following error message with pybricks-micropython 3 build 1733:

robot@ev3dev:~/StallTest$ brickrun -r pybricks-micropython main.py
Traceback (most recent call last):
  File "main.py", line 7, in <module>
ValueError: incompatible .mpy file

Following the code of the test application, which worked well with version 2 - the one, which was installed by default. I only adopted the number and values of some function parameters accordingly:

#!/usr/bin/env pybricks-micropython
from pybricks.hubs import EV3Brick
from pybricks.ev3devices import Motor
from pybricks.parameters import Port, Direction
from pybricks.tools import wait, DataLog, StopWatch

from threading import Thread

ev3 = EV3Brick()
middle_motor = Motor(Port.B, Direction.COUNTERCLOCKWISE)

def logging(log : bool):
    data = DataLog(' time, angle, speed', name='data', timestamp=False)
    watch = StopWatch()

    while log():
        data.log(
            '{:.3f}'.format(watch.time() / 1000),
            '{:5d}'.format(middle_motor.angle()),
            '{:5d}'.format(middle_motor.speed())
        )
        wait(10)

if __name__ == '__main__':
    log_enabled = True
    t = Thread(target = logging, args=[lambda: log_enabled])
    t.start()

    # limits defaults: 1000, 4000, 200
    middle_motor.control.limits(10000, 10000, 200)
    # pid defaults: 3000, 10002, 30, None, 5
    middle_motor.control.pid(3000, 10002, 30, None, 5)
    # stall_tolerances defaults: 15, 200
    middle_motor.control.stall_tolerances(100, 20)

    # move lever to the left stop:
    middle_motor.run_until_stalled(-2000)
    middle_motor.reset_angle(0)
    # move lever to the right stop:
    max_angle = middle_motor.run_until_stalled(2000)

    log_enabled = False

There seems to be an issue with threading. If I remove the thread related lines, the script is working again. Do you have an idea, how to fix this?

[dlech]

from threading import Thread

I didn't think that the .mpy version changed since Pybricks v2.0, but maybe it did. I would suggest avoiding threads if possible, but if not, import from _thread instead of threading.

[Nawor3565]

@Lemru, would you be able to tell me what you did to get 3.1.0 to run? Did you put the updated file on the SD card or the Mindstorm itself? And was that all you did?

[Lemru]

@dlech: Thanks for pointing me into that direction. I wasn't aware of the existence of _thread. Now the script does what it was supposed to.

Edit: It just crossed my mind that I updated the system. Maybe the mpy files have been updated in this context as well.

[Lemru]

@Nawor3565:

Start your EV3 brick with an EV3DEV SD card inserted. Establish a network connection and look on your brick for the IP address. If you have never done this before, this Tutorials page might help you.

On Linux open a terminal, on Windows a command shell or PowerShell. Go to the directory with the new pybricks-micropython module extracted from the downloaded zip file. Then type following command:

scp pybricks-micropython robot@<ip-address>:/usr/local/bin/

You will be asked for a password. The default one is 'maker'. Now connect to your brick via ssh shell with following command

ssh robot@<ip-address>

and enter the password as requested. Switch to the target folder with root rights:

sudo -s
cd /usr/local/bin

When you enter

ls -la pybricks-micropython

you should see exactly one line starting with -rw-r--r--, which indicates that pybricks-micropython has been copied successfully to this directory, but is not yet executable. You need to change this with

chmod ugo+x pybricks-micropython

If you enter

ls -la pybricks-micropython

again, the first characters of the line should have changed to -rwxr-xr-x

You are done!

[Nawor3565]

Thank you so much! I didn't realize I needed to chmod the file, I'll try that today!

[dlech]

cd /usr/bin

FYI, the /usr/bin/ directory is owned by the debian packages, so modifying anything here can break things and updates can overwrite your changes. It is better to put this in /usr/local/bin/ instead.

[Lemru]

You are right, I updated the instruction in case someone should stumble across this issue.

Why didn't version 3 ever make it into the default EV3DEV firmware? What needs to be done to make it happen?

[dlech]

We've been focused on adding support for newer hubs (an there are lots of them!) for v3.x.

[Lemru]

I thought so. I'm coaching WRO Teams in my spare time and we are still using EV3 bricks, at least as long as they work properly. I know from my children as well as from other coaches that many schools are in the same situation. They bought lots of EV3 Education packs and get more and more the impression that Lego has let them down. There is neither the need nor the money to move over to the new spike equipment, at least not as long as the EV3 is competitive. Because of Corona there were no competitions here last year, in 2020 they were canceled. We are using VS Code and started late this year. So we only recently realized that there were some inexplicable differences in the code completion and the pybricks documentation. Investigating these issues led me finally to this discussion. I appreciate your work very much, but I was a bit disappointed to see that there were no pybricks updates since 2020 for the EV3, while the spike hub was obviously more in focus. My concern is to be able to continue using the EV3 without restrictions in competitions such as WRO and FLL. So my first approach was to get the differences in VS Code sorted out. But my overall concern is, to keep the EV3 up to date as long as possible. To my opinion the EV3 still has significant advatages over the spike hub with two additional ports.

Therefore my question: How can I support you to keep the pybricks EV3 project alive?

[dlech]

So we only recently realized that there were some inexplicable differences in the code completion and the pybricks documentation

FYI, there are 2.x docs at https://pybricks.com/ev3-micropython/ and 2.x code completion can be installed with pip install pybricks<3. If something doesn't match between these, please open an issue and we will fix it.

We don't know of any major issues with 2.x so even though there haven't been any updates, it still should work well for most cases.

Therefore my question: How can I support you to keep the pybricks EV3 project alive?

Ideally by finding some funding one way or another: https://github.com/sponsors/pybricks

This is of course more than could be expected of one individual or team but maybe someone like you could do the legwork to find a grant or promote some crowdsourcing with others that feel the same way about keeping EV3 alive?

[dlech]

Update: there is now a new debian package for Pybricks v3.x on ev3dev, see https://github.com/pybricks/support/issues/1034#issuecomment-1564873392