How do I control two PuP crocodiles simultaneously ?

[Selander]

This is right now a hypothetical question, but I'm in process of designing two Powered Up locomotives that I want to run simultaneously.

Loco 1:  white 2ch PuP hub + large PuP motor.

Loco 2: same as above.

Option 1: Most convenient would be to use the specific PuP app Lego designed for the crocodile, but is it possible to use that app for "two crocs" simultaneously?

Option 2 would be to code a custom app ..can someone please share some screenshots of your program, if you have done that?

I'm merely looking for a simple speed control so I'd guess such coding should be easy....

 

Thanks in advance for any suggestions.

 

Edited October 16, 2025 by Selander

[Lok24]

5 hours ago, Selander said:

I'm merely looking for a simple speed control so I'd guess such coding should be easy....

 

You can use the PoweredUp App and  control via screen (sliders) or LEGO remote

http://www.werner-falkenbach.de/bricks/PoweredUp-Sliders.jpg
http://www.werner-falkenbach.de/bricks/PoweredUp-Advanced.jpg
http://www.werner-falkenbach.de/bricks/PoweredUp-Advanced-2.jpg
http://www.werner-falkenbach.de/bricks/PoweredUp-Loop.jpg

Edited October 16, 2025 by Lok24

[Selander]

32 minutes ago, Lok24 said:

You can use the PoweredUp App and  control via screen (sliders) or LEGO remote

Thanks @Lok24. So if I understand you correct, I need to write my own custom program ? 

I thought using the Lego PuP remote wasn't possible when using large motors....that it would only be a on/off full throttle ...?(!)

[Lok24]

1 minute ago, Selander said:

Thanks @Lok24. So if I understand you correct, I need to write my own custom program ? 

Yes, I just added some links 

(can't  insert picture-URLs any more ???)

3 minutes ago, Selander said:

I thought using the Lego PuP remote wasn't possible when using large motors....that it would only be a on/off full throttle ...?(!)

Yes if you connect it with the hub.

But you can connect 2 hubs and the remote all three with the app.

[Selander]

@Lok24. Thanks for the links, I will study them carefully ! 🙌🤗

@Lok24. Is it also possible to just have one slider, but control both hubs simultaneously?

[Lok24]

13 minutes ago, Selander said:

Is it also possible to just have one slider, but control both hubs simultaneously?

Sure, if you look at the "Loop" (which is the program) it uses three values:

Hub (HUB1)
Port (A)
Reference to the slider (1)

You should copy the entire program, then use HUB1 and HUB2, but as the reference to slider-symbol in both blocks reference to the "1"

 

[Selander]

1 minute ago, Lok24 said:

Sure, if you look at the "Loop" (which is the program) it uses three values:

Hub (HUB1)
Port (A)
Reference to the slider (1)

You should copy the entire program, then use HUB1 and HUB2, but as the reference to slider-symbol in both blocks reference to the "1"

 

Great, thanks a million ✅👍

[zephyr1934]

Nice!

[Brickstone_City]

Hi,

If you are looking for more advanced programming you can take a look at Pybricks:

https://pybricks.com

You need to load the firmware once to each hub, then you can run Pybricks programs on them. Downside is you need to load the program each time you turn on the hub.

For multiple traction you can for example couple multiple hubs copying each other in several distributed locomotives. Also, you can get much smoother control.

[Lok24]

45 minutes ago, Brickstone_City said:

Downside is you need to load the program each time you turn on the hub.

This is wrong, the program remains stored in the hub and starts if you turn on the the hub and press the green button.

And you cannot use a smart device to control, only the remote, XBox Controller or a second hub.

Edited October 27, 2025 by Lok24

[Selander]

1 hour ago, Brickstone_City said:

Hi,

If you are looking for more advanced programming you can take a look at Pybricks:

https://pybricks.com

You need to load the firmware once to each hub, then you can run Pybricks programs on them. Downside is you need to load the program each time you turn on the hub.

For multiple traction you can for example couple multiple hubs copying each other in several distributed locomotives. Also, you can get much smoother control.

Thanks, I'm aware of this option, but not ready to walk along this path... I prefer a PuP app based solution.

[dr_spock]

The PU remote can pair with more than one PU hub, if I recall.  I guess one trick could be to fool the PU hub thinking that a PU train motor is attached. With the "train motor", one would get the variable speed control with the PU remote instead of the on-off.  It can be done with an adapter going between motor and hub where the hub end of the adapter is wired to ID as a PU train motor.  No programming or app are required.

 

 

[Lok24]

29 minutes ago, dr_spock said:

The PU remote can pair with more than one PU hub, if I recall.

True, but not needed with the app, where its just one of 4 devices.

 

31 minutes ago, dr_spock said:

No programming or app are required.

Indeed.

[Brickstone_City]

On 10/27/2025 at 7:15 PM, Lok24 said:

This is wrong, the program remains stored in the hub and starts if you turn on the the hub and press the green button.

And you cannot use a smart device to control, only the remote, XBox Controller or a second hub.

Alright - thanks, didn't notice that. Only tried to connect the remote first, and this did not work :-)

But you can use the program to control, of course ;-)

[Selander]

2 hours ago, dr_spock said:

The PU remote can pair with more than one PU hub, if I recall.  I guess one trick could be to fool the PU hub thinking that a PU train motor is attached. With the "train motor", one would get the variable speed control with the PU remote instead of the on-off.  It can be done with an adapter going between motor and hub where the hub end of the adapter is wired to ID as a PU train motor.  No programming or app are required.

 

 

Now that's a clever hack. Well done.

[Lok24]

12 hours ago, Selander said:

Now that's a clever hack. Well done.

Yes, we used that years ago, when there was no control panel in PuP-App and Pybricks not that easy to use as today.

But: you loose all the advantages of the motors, like smooth control, precise speed control or load control and so on

 

[Selander]

28 minutes ago, Lok24 said:

Yes, we used that years ago, when there was no control panel in PuP-App and Pybricks not that easy to use as today.

But: you loose all the advantages of the motors, like smooth control, precise speed control or load control and so on

 

Agreed, I do plan to use the PuP app, for sure. But its interesting to see what alternative solutions people have come up with. Trainheads are part of a very creative community.

[Selander]

@Lok24 I created the custom program in PuP app yesterday, acc to your instructions/proposals and it works perfectly. Thanks again for your kind advice 🙌