Brodcast/Recive/Unpack of detected Color

[konrad20100]

Dear experts

I have to do a school project, with 5 hubs (with Pybrics-blocks).
Task:
A car made from Lego brics (hub A) has to do some path and drive onto a conveyor belt. The color sensor (on Hub B) has to determine the color of the car (Yellow, Red, Blue or Green) and BRODCAST data.
Hub C should RECIVE/UNPACK data and, moves the conveyor belt to the appropriate position (motor rotation for 360, 720, 1080 or 1440°).
HUB B BRODCAST data that the conveyor belt has finished.
Then the car (HUB A) should RECIVE/UNPACK data and drives into the appropriate garage.
I have assembled the model, but I can't make a working program.

I found information on GitHub that it is not possible to broadcast color data, but it is necessary to convert the color in to a number (Yellow=1, R=2, B=3 and G=4....).
Which BLOCK can I use to convert detected color to a number?
How do I create a BROADCAST LIST? Do I need a separate BROADCAST LIST for each color or one LIST for all 4 colors?

I wanted to use the tutorials https://www.youtube.com/watch?v=WzmcihSV2YE or https://www.youtube.com/watch?v=liv37b7PXUQ as a basis, but they don't help me.
It is working with reflected light, ambient light, force sensor, ulttrasonic sensor, bat not with color detection (standard lego color) . I spend whole halloween weekt for this task,.. I'm down, and I'm running out of time.

Does Pybrics comunity have any video or text tutorials regarding this topic?
Maybe I just didn't search on adequate folders or pages.

Regards
K

[dlech]

Which BLOCK can I use to convert detected color to a number?

I found a completely not obvious way to do this. 🤓

The Color type is iterable, which means we can put it in a for loop and it will loop 3 times, once with the hue, once with the saturation and once with the value. The hue represents the actual color, so that is the only value we really need. So we can just return from inside the loop to get the first value. The loop won't run any more since we returned.

We can put that in a task to make it reusable and then use it to convert a color to a number.

This program outputs:

Color.RED is 0
Color.GREEN is 120
Color.BLUE is 240

How do I create a BROADCAST LIST?

The broadcast block in the palette already has a list in it.

Do I need a separate BROADCAST LIST for each color or one LIST for all 4 colors?

If you can only detect one color at a time (because there is only one color sensor), then you only need to send that one color. You can delete the list and just put the color in the broadcast block.

[konrad20100]

V V ned., 2. nov. 2025 ob 22:35 je oseba David Lechner < ***@***.***> napisala:

…

Which BLOCK can I use to convert detected color to a number? I found a completely not obvious way to do this. 🤓 pybricks_program_2025-11-02T21_27_41.png (view on web) <https://github.com/user-attachments/assets/27ab42dd-fd84-4727-8e07-6bb2440d41d2> The Color type is iterable, which means we can put it in a for loop and it will loop 3 times, once with the hue, once with the saturation and once with the value. The hue represents the actual color, so that is the only value we really need. So we can just return from inside the loop to get the first value. The loop won't run any more since we returned. We can put that in a task to make it reusable and then use it to convert a color to a number. This program outputs: Color.RED is 0Color.GREEN is 120Color.BLUE is 240 How do I create a BROADCAST LIST? The broadcast block in the palette already has a list in it. image.png (view on web) <https://github.com/user-attachments/assets/4a46f8e3-1b98-400a-b50c-3e15be23a4f2> Do I need a separate BROADCAST LIST for each color or one LIST for all 4 colors? If you can only detect one color at a time (because there is only one color sensor), then you only need to send that one color. You can delete the list and just put the color in the broadcast block. — Reply to this email directly, view it on GitHub <#2418 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BUNVPNNMXDCLF5BHNASNTKD32ZTJFAVCNFSM6AAAAACK5QMLDGVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTIOBVGMYDSOI> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[Eco-Beny]

Hi.

I tried a few times, I'm not doing something right....

1. HUB-1 - broadcast

• So first I need to transform color to a number with PRINT . If I use the PRINT block as you shown, is that solved or do I need to type a number for each color (e.g. R is 0, Y is 60)?
  There are four colors. PRINT blocks have to be four as well?
  The same goes for BROADCAST: Four colors, four broadcast blocks?

2. HUB-2 - recive

What exactly should I put in UNPACK: block OBSERVE or block READ ?

3. Beside groups SET-UP and PROGRAM, there should also be TASK group . Just as You show, or for each colour separately ?

I hope I didn't ruin your Friday afternoon...
K.