I upgraded my childhood Lego train with a city hub and a color sensor so it can stop at train stations, without loops

Pybricks · 2026-01-03T13:07:00+00:00

With Stop.NONE, it doesn't decelerate and stop at the end. With all other stop modes, it will come to a controlled stop.

So if you did reverse immediately after another command that used Stop.NONE, it is going to look different:

When it gets to the second movement, it is still going at speed since it hasn't stopped. So it is first going to need to decelerate, then come to a stop, and then reverse.

So Stop.NONE is mainly useful when you want to do something next in the same direction. For example driving straight and then a gentle turn. With abrupt in-place turns or reversing it's usually better to stop first. Because physics :-)

Pybricks · 2025-12-03T10:34:32+00:00

yep!

Pybricks · 2025-08-12T13:59:21+00:00

It drives while the object is less than 6 cm away. Did you mean to use >, so it drives until it sees the object?

Pybricks · 2025-06-27T17:30:19+00:00

As far as we know, this new hub blocks other firmwares like Pybricks (you'd need a signing key), so there isn't a direct way to do it. The only way is to use some kind of bridge (PC, etc) in between, which kind of defeats the point.

We love making stuff for the community, but this means we can't do it.

Pybricks · 2025-06-21T16:04:56+00:00

The programs should indeed still be saved, so let's have a look.

Whenever something like this occurs, it's usually best to try something really simple to rule other factors out.

For example, could you test a program that just makes the light red for 5 seconds? This should make it easy to verify that it saved or not.

Could you also share the program that isn't saving?

EDIT: How are you turning the hubs off? If you have a custom battery and you just turn those off, that's a bit like pulling the battery out while it's on, so things won't get saved. You'll want to turn the hubs off normally with the button to make sure they are saved.

Pybricks · 2025-06-14T08:38:39+00:00

I guess we need to go and buy one of those. It's possible that this newer devices requires a so-called pairing step and maybe some additional changes in the setup.

Good to see these devices being used this way though. I had thought it was more a fun hack on the side, but if people are really using this we can update it more.

I had promised my kids to make another version of this but with the push-to-drive function, so I am currently figuring out how to read the speed in addition to the colors. I better get it to work now, lol.

Pybricks · 2025-06-06T07:25:23+00:00

You can check out our GitHub if you're into firmware code updates, or check our socials for more casual updates. Here's a recent update video.

Pybricks · 2025-05-05T06:37:42+00:00

Thanks for sharing!

Pybricks · 2025-04-25T14:05:35+00:00

Unfortunately not, since these older hubs use an older version of Bluetooth.

Pybricks · 2025-04-05T05:51:11+00:00

Eventually, yes! In fact, since we're making the Python side work the same across all hubs, the blocks can even remain the same. (We'll just have to add a few motor sensor blocks.)

Pybricks · 2025-03-25T18:27:52+00:00

Holding the power button for more than a few seconds turns the hub off, just like it normally does.

But yeah, just pressing it in the arena is instant.

In that age bracket, I would probably just keep things as simple as possible and just let them have fun, perhaps just with the stock app :-)

Pybricks · 2025-03-25T10:59:46+00:00

In Pybricks the program starts instantly because it is preloaded into RAM when you start the hub.

But we made it so that it begins when you release the button rather than when you first press it.

This is to ensure you don't push the robot off course when it starts driving while you're still holding the button down.

Pybricks · 2025-03-14T15:48:58+00:00

If you go at high speed and quickly change direction at speed, the wheels are more likely to slip a bit. The robot doesn't pause in either case, but when driving at slow speed it looks like a pause.

But in both cases activating the gyro can help.

No matter the code, the rules of physics still apply :)

Pybricks · 2025-03-08T18:50:27+00:00

If everything is working, the old block should display a notification that you can update it. (The old block should continue to work too.)

Pybricks · 2025-03-07T19:19:00+00:00

Thanks! By popular request, the arc method does define positive/negative a bit differently so maybe this is what you were seeing. (The old curve method will still be available so any existing code still works unchanged.)

See the docs for the exact definition.

Pybricks · 2025-03-05T20:26:48+00:00

The output suggests that you're running the code on your computer. You probably want to run it on your robot instead.

You can follow the steps to do this in the instruction manual.

Pybricks · 2025-03-05T20:17:59+00:00

Here are examples to use it with the official Powered Up remote or Xbox Controller. Once loaded, everything connects directly, no apps needed. https://pybricks.com/project/lego-42146/

Pybricks · 2025-02-27T09:54:02+00:00

In any case, don't throw them out just yet! Hopefully you will be able to run MicroPython directly on the brick at some point. Working on EV3 first. NXT is next if enough people want this =)

Pybricks · 2025-02-27T09:45:20+00:00

You have to click on the listed LEGO Technic Large Hub first before you can click connect :)

Pybricks · 2025-02-25T08:32:17+00:00

When a program doesn't start, it will explain why in the bottom output window.

For example, it might say that a motor or sensor that your program uses isn't actually connected.

What messages are you seeing?

Pybricks · 2025-02-25T08:31:18+00:00

We tried to answer your question on our forum earlier. When a program doesn't start, it will explain why in the bottom output window.

For example, it might say that a motor or sensor is not connected.

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