From 2c714a6803fa106dcf23f40f8a0e5876cbf16db4 Mon Sep 17 00:00:00 2001
From: Sam Scholten
Date: Tue, 14 Oct 2025 16:43:06 +1000
Subject: Resolve acquisition hang and pause plot updates on stop

---
 picostream/cli.py    |  2 +-
 picostream/dfplot.py | 11 +++++++++--
 picostream/main.py   |  3 +++
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/picostream/cli.py b/picostream/cli.py
index 8fc65b0..23922e3 100644
--- a/picostream/cli.py
+++ b/picostream/cli.py
@@ -327,8 +327,8 @@ class Streamer:
 
         logger.info("Stopping data acquisition and saving...")
 
-        self._join_threads()
         self.pico_device.close_device()
+        self._join_threads()
 
         logger.success("Shutdown complete.")
 
diff --git a/picostream/dfplot.py b/picostream/dfplot.py
index 63ffe33..ebf6f03 100644
--- a/picostream/dfplot.py
+++ b/picostream/dfplot.py
@@ -105,10 +105,9 @@ class HDF5LivePlotter(QWidget):
         # Setup UI
         self.setup_ui()
 
-        # Setup update timer
+        # Setup update timer, which is controlled externally
         self.timer = QTimer()
         self.timer.timeout.connect(self.update_from_file)
-        self.timer.start(self.update_interval_ms)
 
         logger.info(
             f"HDF5LivePlotter initialized: path={hdf5_path}, interval={update_interval_ms}ms"
@@ -133,6 +132,14 @@ class HDF5LivePlotter(QWidget):
         self.curve.setData([], [])  # Clear plot
         self.check_file_exists()
 
+    def start_updates(self) -> None:
+        """Starts the plot update timer."""
+        self.timer.start(self.update_interval_ms)
+
+    def stop_updates(self) -> None:
+        """Stops the plot update timer."""
+        self.timer.stop()
+
     def setup_ui(self) -> None:
         """Sets up the main window, widgets, and plot layout."""
         layout = QVBoxLayout(self)
diff --git a/picostream/main.py b/picostream/main.py
index a882b80..9fdb423 100644
--- a/picostream/main.py
+++ b/picostream/main.py
@@ -205,9 +205,11 @@ class PicoStreamMainWindow(QMainWindow):
         self.worker.error.connect(self.on_acquisition_error)
 
         self.thread.start()
+        self.plotter.start_updates()
 
     def stop_acquisition(self) -> None:
         """Stop the background data acquisition."""
+        self.plotter.stop_updates()
         if self.worker:
             self.worker.stopRequested.emit()
         self.stop_button.setEnabled(False)
@@ -215,6 +217,7 @@ class PicoStreamMainWindow(QMainWindow):
     def on_acquisition_finished(self) -> None:
         """Handle acquisition completion (both success and failure)."""
         print("Acquisition finished.")
+        self.plotter.stop_updates()
         self.start_button.setEnabled(True)
         self.stop_button.setEnabled(False)
         self.thread = None
-- 
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