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Why broadcast and volume blocks don't work together?

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CH

CodeHelper_Mike

Posted on July 21, 2025 • Beginner

🔊 Broadcast and Volume Block Issue

Hey everyone! I’m having trouble with my Scratch project where I’m using broadcasts with volume blocks. The code doesn’t seem to work as expected:

Main Script:

when green flag clicked
forever
  broadcast [message 1]
  broadcast [message 2]
end

Receiver 1:

when I receive [message 1]
set volume to (100) %
change [counter 1] by (1)
show variable [counter 1]

Receiver 2:

when I receive [message 2]
change [counter 2] by (1)
set volume to (100) %
show variable [counter 2]

The variables aren’t updating properly and the volume seems to interfere. What am I doing wrong? 🤔

ST

ScratchTutor_Alex

Replied 1 hour later • ⭐ Best Answer

Great question @CodeHelper_Mike! This is a common timing issue with broadcasts and volume blocks. Here’s what’s happening and how to fix it:

🔍 The Problem

The issue occurs because:

  • Volume blocks are yielding blocks - they pause the script briefly
  • Your broadcasts are sent in rapid succession in a forever loop
  • When a new broadcast is received before the previous script finishes, it restarts the receiver script

📊 Timing Flow Diagram

sequenceDiagram participant Main as Main Script participant R1 as Receiver 1 participant R2 as Receiver 2 Main->>R1: broadcast [message 1] R1->>R1: set volume (yields) Main->>R2: broadcast [message 2] (immediately) R2->>R2: change counter Main->>R1: broadcast [message 1] (again!) Note over R1: Script restarts before completion! R1->>R1: set volume (yields) Main->>R2: broadcast [message 2] (again!) Note over R2: Script restarts before completion!

✅ Solution 1: Use “broadcast and wait”

Replace your main script with this:

    when flag clicked
forever
broadcast [message 1 v] and wait
broadcast [message 2 v] and wait
end

This ensures each broadcast completes before the next one starts.

✅ Solution 2: Remove yielding blocks from receivers

If you don’t need the volume blocks in the receivers, remove them:

    when I receive [message 1 v]
change [counter 1 v] by [1]
show variable [counter 1 v]

when I receive [message 2 v]
change [counter 2 v] by [1]
show variable [counter 2 v]

✅ Solution 3: Use a different approach

If you need volume control, set it once at the start:

    when flag clicked
set volume to [100] %
forever
broadcast [message 1 v]
broadcast [message 2 v]
wait [0.1] seconds
end

🎯 Best Practice Tips

  • Avoid yielding blocks in frequently called broadcast receivers
  • Use “broadcast and wait” when you need synchronization
  • Add small waits in forever loops to prevent overwhelming the system
  • Test your timing by adding say blocks to see execution order

Hope this helps! Let me know if you need any clarification! 😊

CH

CodeHelper_Mike

Replied 30 minutes later

@ScratchTutor_Alex This is exactly what I needed! 🎉

The “broadcast and wait” solution worked perfectly. I didn’t realize that volume blocks could cause timing issues. Thanks for the detailed explanation!

VB

Vibelf_Community

Pinned Message • Moderator

🚀 Master Broadcast Timing in Scratch!

Great discussion on broadcast synchronization! For those looking to dive deeper into advanced Scratch programming concepts, our community can help you with:

  • 🔄 Complex broadcast patterns
  • ⏱️ Timing and synchronization
  • 🎵 Audio programming techniques
  • 🐛 Advanced debugging strategies

📚 Related Topics

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