9 files changed, 36 insertions, 5 deletions
diff --git a/ui/__pycache__/add_device_dialog.cpython-312.pyc b/ui/__pycache__/add_device_dialog.cpython-312.pyc
index e9aab22..2da95a6 100644
--- a/ui/__pycache__/add_device_dialog.cpython-312.pyc
+++ b/ui/__pycache__/add_device_dialog.cpython-312.pyc
diff --git a/ui/__pycache__/control_editor.cpython-312.pyc b/ui/__pycache__/control_editor.cpython-312.pyc
index 42855d5..ccecd3e 100644
--- a/ui/__pycache__/control_editor.cpython-312.pyc
+++ b/ui/__pycache__/control_editor.cpython-312.pyc
diff --git a/ui/__pycache__/control_panel.cpython-312.pyc b/ui/__pycache__/control_panel.cpython-312.pyc
index 8761466..1c101a8 100644
--- a/ui/__pycache__/control_panel.cpython-312.pyc
+++ b/ui/__pycache__/control_panel.cpython-312.pyc
diff --git a/ui/__pycache__/main_window.cpython-312.pyc b/ui/__pycache__/main_window.cpython-312.pyc
index a290571..d89b2e6 100644
--- a/ui/__pycache__/main_window.cpython-312.pyc
+++ b/ui/__pycache__/main_window.cpython-312.pyc
diff --git a/ui/add_device_dialog.py b/ui/add_device_dialog.py
index 50f234d..7e8e935 100644
--- a/ui/add_device_dialog.py
+++ b/ui/add_device_dialog.py
@@ -401,7 +401,7 @@ class AddDeviceDialog(QDialog):
         self.created_device = None
         self.setWindowTitle("Add Device")
         self.setMinimumSize(480, 460)
-        self.resize(500, 520)
+        self.resize(500, 600)
         self._build()
 
     def _build(self):
diff --git a/ui/control_editor.py b/ui/control_editor.py
index 4d18aef..901d6f8 100644
--- a/ui/control_editor.py
+++ b/ui/control_editor.py
@@ -51,6 +51,7 @@ class ControlSpec:
     icon:         str   = "⏻"
     device_id:    str   = ""
     channel_id:   str   = ""
+    active_low:   bool  = False
     # Type-specific params
     unit:         str   = ""
     min_val:      float = 0.0
@@ -206,6 +207,9 @@ class ControlEditorDialog(QDialog):
         self._ch_cb.setInsertPolicy(QComboBox.InsertPolicy.NoInsert)
         hw_form.addRow("Channel / Pin:", self._ch_cb)
 
+        self._active_low_chk = QCheckBox("Active-low output (ON sends LOW)")
+        hw_form.addRow("Polarity:", self._active_low_chk)
+
         self._ch_hint = QLabel("")
         self._ch_hint.setObjectName("traceSource")
         self._ch_hint.setWordWrap(True)
@@ -255,6 +259,7 @@ class ControlEditorDialog(QDialog):
         # Channel (populated after device selection)
         self._on_dev_changed()
         self._ch_cb.setCurrentText(self.spec.channel_id)
+        self._active_low_chk.setChecked(bool(self.spec.active_low))
 
         # Params
         for name, panel in self._param_panels.items():
@@ -263,6 +268,7 @@ class ControlEditorDialog(QDialog):
     def _on_type_changed(self, type_name: str):
         idx = list(_PARAM_PANELS.keys()).index(type_name)
         self._stack.setCurrentIndex(idx)
+        self._active_low_chk.setEnabled(type_name == "On/Off Switch")
         # Auto-set title if still default
         if not self._title_edit.text() or \
            self._title_edit.text() in CONTROL_TYPES:
@@ -309,6 +315,7 @@ class ControlEditorDialog(QDialog):
             icon=CONTROL_ICONS.get(ctype, "⚙"),
             device_id=self._dev_cb.currentData() or "",
             channel_id=channel_id,
+            active_low=self._active_low_chk.isChecked(),
         )
         # Save type-specific params
         panel = self._param_panels.get(ctype)
diff --git a/ui/control_panel.py b/ui/control_panel.py
index efd4f17..7a3e416 100644
--- a/ui/control_panel.py
+++ b/ui/control_panel.py
@@ -43,16 +43,24 @@ class ControlWidget(QFrame):
 
     def __init__(self, title: str, icon: str = "⚙",
                  device_id: str = "", channel_id: str = "",
-                 registry: Optional[DeviceRegistry] = None):
+                 registry: Optional[DeviceRegistry] = None,
+                 active_low: bool = False):
         super().__init__()
         self.title      = title
         self.icon       = icon
         self.device_id  = device_id
         self.channel_id = channel_id
         self.registry   = registry
+        self.active_low = active_low
         self.setObjectName("controlWidget")
         self._build_frame()
 
+    def _logic_level(self, enabled: bool) -> float:
+        """Map logical ON/OFF to electrical level, respecting active-low outputs."""
+        if self.active_low:
+            return 0.0 if enabled else 1.0
+        return 1.0 if enabled else 0.0
+
     def _build_frame(self):
         """Build the common outer frame; subclasses fill self._body."""
         outer = QVBoxLayout(self)
@@ -155,7 +163,7 @@ class OnOffSwitch(ControlWidget):
         # Re-polish so QSS picks up new objectName
         for w in (self._btn, self._indicator, self._state_lbl):
             w.style().unpolish(w); w.style().polish(w)
-        self._write(1.0 if checked else 0.0)
+        self._write(self._logic_level(checked))
 
 
 # ══════════════════════════════════════════════════════════════════════════════
@@ -568,6 +576,7 @@ class ControlPanel(QWidget):
             spec = ControlSpec(
                 title=widget.title, icon=widget.icon,
                 device_id=widget.device_id, channel_id=widget.channel_id,
+                active_low=getattr(widget, "active_low", False),
             )
         wrapper = self._make_wrapper(widget, spec)
         self._widgets.append(widget)
@@ -673,6 +682,7 @@ def _build_widget_from_spec(spec, registry: DeviceRegistry) -> Optional[ControlW
         device_id=spec.device_id,
         channel_id=spec.channel_id,
         registry=registry,
+        active_low=getattr(spec, "active_low", False),
     )
     t   = spec.control_type
     ttl = spec.title
diff --git a/ui/main_window.py b/ui/main_window.py
index 9df7ef7..d4bb203 100644
--- a/ui/main_window.py
+++ b/ui/main_window.py
@@ -92,6 +92,12 @@ class MainWindow(QMainWindow):
         self._log_btn.setEnabled(False); self._log_btn.clicked.connect(self._toggle_log)
         tb.addWidget(self._log_btn)
 
+        self._clear_btn = QPushButton("⌫  Clear")
+        self._clear_btn.setObjectName("toolbarSectionBtn")
+        self._clear_btn.setToolTip("Clear plot history")
+        self._clear_btn.clicked.connect(self._clear_history)
+        tb.addWidget(self._clear_btn)
+
         tb.addWidget(_sep())
 
         dev_btn = QPushButton("⊞  Devices")
@@ -265,12 +271,15 @@ class MainWindow(QMainWindow):
             processor=self.processor,
             control_panel=self._ctrl,
             settings_ref=self._settings,
+            engine=self.engine,
         )
         if plot_cfg:
             self._chart.apply_layout(plot_cfg)
         else:
             self._chart.refresh()
         # Refresh open windows
+        if self._win_devices:
+            self._win_devices.refresh()
         if self._win_plot:
             self._win_plot.refresh_channels()
         self._status.setText(f"Profile loaded: {profile.name}")
@@ -309,6 +318,11 @@ class MainWindow(QMainWindow):
             self._log_btn.setEnabled(False); self._clock.stop()
             self._status.setText("Stopped")
 
+    def _clear_history(self):
+        self.engine.clear_history()
+        self._chart.refresh()
+        self._status.setText("History cleared.")
+
     def _toggle_log(self, c: bool):
         if c:
             p = self.engine.start_logging(
diff --git a/ui/plot_builder.py b/ui/plot_builder.py
index beda116..ad6d231 100644
--- a/ui/plot_builder.py
+++ b/ui/plot_builder.py
@@ -356,8 +356,8 @@ class PlotBuilderWindow(QWidget):
                          else build_default_layout(registry, processor)
 
         self.setWindowTitle("Plot Builder")
-        self.setMinimumSize(700, 560)
-        self.resize(800, 680)
+        self.setMinimumSize(700, 780)
+        self.resize(800, 780)
         self._blocks: List[PlotBlock] = []
         self._build()
         self._populate()