Push button blocks in GNU Radio, and how to continuously display a variable state such as the one changed by a push button or other mechanism

Is there push button block in GNU Radio Companion?

Yep — there is 👍

In GNU Radio (QT GUI) you’ve got a couple of button-style options, depending on what behavior you want:

✅ QT GUI Push Button

• Block name: QT GUI Push Button
• What it does:
  Sends a message once each time you click it (momentary action).
• Use case:
  Triggering events like:
  • Resetting a counter
  • Taking a snapshot
  • Starting a calibration
• Important:
  It does not output a stream, only a message, so you connect it to blocks with message inputs.

🔁 QT GUI Toggle Button

• Block name: QT GUI Toggle Button
• What it does:
  Latches between 0/1 (or True/False).
• Use case:
  On/off control, enable/disable paths, gating logic.

🧓 WX GUI Button (legacy)

• Exists, but deprecated — best avoided unless you’re maintaining old flowgraphs.

Practical tip

If you want the button to affect stream processing, the usual pattern is:

Push Button → Message Debug / Variable / Message Strobe → Stream logic

(e.g. Message → Variable → Multiply Const)

Is there a GUI to continuously display a variable state in GNU Radio Companion?

Yep — there is, and it’s pretty handy 👍

In GNU Radio (QT GUI) you’ve got a few solid ways to continuously display a variable’s current value, depending on how that variable is updated.

✅ QT GUI Label

Best direct answer to your question

• Block: QT GUI Label
• What it does:
  Displays the current value of a variable and updates automatically.
• Works with:
  • Normal variables
  • Variables updated via message ports
• Typical use:
  Showing gain, frequency, mode flags, counters, state machines, etc.

You just set the “Label” and “Variable” fields to the variable name.

🔁 QT GUI Number Sink

• Displays numeric values over time
• Good if your “variable” is actually a stream
• Overkill if you only want the current state

📬 Message → Variable → Label (common pattern)

If the variable changes via messages:

Message source → Variable block → QT GUI Label

Examples:

• Push Button → Variable → Label
• Message Debug → sanity check + Label

🧠 For non-numeric states

If your variable represents state (e.g. "IDLE", "TRACKING", "CALIBRATING"):

• Use:
  • QT GUI Label
  • Format the text (e.g. State: TRACKING)
• Update via a message-based variable

Pro tip (radio-astronomy friendly 😉)

For things like:

• Integration count
• Fringe detected / not detected
• Antenna selected
• Calibration phase

QT GUI Label + message-updated variable is the cleanest, least hacky solution.