PR#47 (L): Implemented basic trigger logic

CMakeLists.txt

@@ -48,6 +48,7 @@ set(SOURCES_LIST
     capture/src/waveform_parser.cpp
     capture/src/waveform_ring_buffer.cpp
     core/src/waveform_scaling.cpp
+    core/src/waveform_trigger.cpp
     core/src/instrument_scaling_profile.cpp
     ${imgui_SOURCE_DIR}/imgui.cpp
     ${imgui_SOURCE_DIR}/imgui_draw.cpp
@@ -65,6 +66,7 @@ set(HEADERS_LIST
     capture/inc/waveform_parser.h
     capture/inc/waveform_ring_buffer.h
     core/inc/waveform_scaling.h
+    core/inc/waveform_trigger.h
     core/inc/instrument_model.h
     core/inc/instrument_scaling_profile.h
 )
@@ -85,6 +87,10 @@ set(WAVEFORM_SCALING_TEST_SOURCES_LIST
     tests/waveform_scaling_test.cpp
 )
 
+set(WAVEFORM_TRIGGER_TEST_SOURCES_LIST
+    tests/waveform_trigger_test.cpp
+)
+
 set(INSTRUMENT_SCALING_PROFILE_TEST_SOURCES_LIST
     tests/instrument_scaling_profile_test.cpp
 )
@@ -177,6 +183,16 @@ if(BUILD_TESTING)
     enable_project_warnings(waveform_scaling_tests)
     add_test(NAME waveform_scaling COMMAND waveform_scaling_tests)
     add_dependencies(${APP_NAME} waveform_scaling_tests)
+    add_executable(waveform_trigger_tests
+        ${WAVEFORM_TRIGGER_TEST_SOURCES_LIST}
+        core/src/waveform_trigger.cpp
+    )
+    target_include_directories(waveform_trigger_tests PRIVATE
+        ${CMAKE_CURRENT_SOURCE_DIR}/core/inc
+    )
+    enable_project_warnings(waveform_trigger_tests)
+    add_test(NAME waveform_trigger COMMAND waveform_trigger_tests)
+    add_dependencies(${APP_NAME} waveform_trigger_tests)
     add_executable(instrument_scaling_profile_tests
         ${INSTRUMENT_SCALING_PROFILE_TEST_SOURCES_LIST}
         core/src/instrument_scaling_profile.cpp

HISTORY.md

@@ -553,4 +553,70 @@ Records key decisions, structural changes, and completed development stages.
   headroom is deferred to a later stage. The software zero reference already
   yields a correct 0 V reading.
 
+### Stage 4 - Added edge trigger detection
+
+- Added a new `oscilloscope::core` trigger module (`core/inc/waveform_trigger.h`,
+  `core/src/waveform_trigger.cpp`) with an `ETriggerSlope` enum and
+  `findEdgeTrigger`, which scans a sample buffer for the first rising or
+  falling crossing of a level starting at a given index.
+- Added `tests/waveform_trigger_test.cpp` covering rising and falling edges,
+  the no-crossing case, the start-index skip, and the null/short-buffer guards,
+  and registered the `waveform_trigger` test in `CMakeLists.txt`.
+- Wired the trigger into `app/main.cpp`: added a Trigger panel with a source
+  selector (CH1, CH2, ALT, EXT, EXT/10), a slope selector (Rising/Falling), a
+  level slider, and a mode selector (Auto, Normal, Single). Drew a horizontal
+  level line and a vertical trigger-position marker over the waveform, and used
+  the detected trigger sample as the readout reference. Software edge detection
+  runs on CH1/CH2 (ALT falls back to CH1; EXT and EXT/10 have no in-software
+  signal). Auto free-runs, Normal draws only when a trigger is found, and
+  Single freezes the first triggered frame until the Rearm button is pressed.
+- Modelled the trigger controls as `ETriggerMode`, `ETriggerSource`, and
+  `ETriggerSlope` enumerations with option tables that keep each value next to
+  its label (mirroring the scaling-profile step tables), so the combo labels
+  cannot drift from the enumerators.
+
+### Stage 4 - Held triggered frames and a trigger reference marker
+
+- Fixed Normal mode to hold the last triggered frame until the next trigger
+  instead of blanking the display when a frame contained no edge. Normal and
+  Single now share one held-frame path: Single captures once per arm, Normal
+  refreshes the held frame on every new trigger, and Auto free-runs live.
+- Added a "T" reference marker at the top of the display marking the sweep
+  trigger point, alongside the existing vertical trigger line.
+
+### Stage 4 - Aligned the trace to a movable trigger point
+
+- Reworked the trigger point so it is a fixed, user-movable horizontal
+  reference: added a Position control and shifted the displayed trace so the
+  triggering edge lands exactly under the "T" marker, with pre-trigger samples
+  to its left and post-trigger samples to its right.
+- Added a `horizontalOffset` parameter to `drawChannelWaveform` and drew the
+  vertical reference and "T" marker at the fixed trigger position instead of at
+  the raw sample index of the detected edge.
+- Armed the trigger only past a pre-trigger window sized by the Position
+  control, so the aligned trace keeps enough history to fill the display left
+  of the "T" marker instead of leaving an empty region.
+
+### Stage 4 - Windowed the record under a fixed trigger marker
+
+- Displayed only a fraction of the captured record (a window) so the surplus
+  samples act as pre/post-trigger reserve, letting the trace fill the whole
+  display under the fixed "T" marker without an empty region on either side.
+- Slid the window so the trigger sample sits under the marker, clamping the
+  window to the record bounds; at the reserve limit the marker drifts slightly
+  rather than exposing an empty edge.
+- Replaced the pixel-shift parameter of `drawChannelWaveform` with a window
+  start and length, and added `computeDisplayWindow` to size the window.
+- Verified on a physical Hantek DSO-2250 with a noise signal, the trigger
+  centered, and Normal sweep: the trace reaches the right edge and starts at
+  the left edge with no gaps. Confirmed at Position 0 and Position 90 as well.
+
+### Next windowing tasks
+
+- Phase 2: derive the display window length from the Timebase control using the
+  device's real sample period, so the Timebase combo drives the horizontal
+  span. Requires confirming the true sample period from the reference USB
+  captures before wiring it to the window length.
+
+
 

README.md

@@ -15,7 +15,8 @@ The application currently provides:
 - supported Hantek device discovery and connection through libusb;
 - FX2 firmware upload and operational-device re-enumeration;
 - Start/Stop-controlled endpoint polling;
-- bounded USB error recovery and safe device-loss handling.
+- bounded USB error recovery and safe device-loss handling;
+- live two-channel waveform rendering with edge triggering.
 
 Capture-state responses and sample buffers are decoded by deterministic,
 hardware-independent parser functions. Each supported-device entry supplies its
@@ -25,8 +26,10 @@ worker reads and queues the complete profile-defined sample buffer, then starts
 the next capture. A processing worker decodes complete captures and publishes
 the latest frame and trigger point safely for rendering. Deterministic
 functions convert raw capture samples into volts and elapsed capture time from
-the selected voltage-scale and timebase settings. Live waveform rendering is
-not yet implemented.
+the selected voltage-scale and timebase settings. Both channels are plotted on
+the display grid with Auto, Normal, and Single edge triggering, a movable
+trigger Position with a fixed "T" reference marker, and a display window that
+keeps the trace filling the full width with pre/post-trigger reserve.
 
 ## Planned Stack
 
@@ -217,18 +220,14 @@ CI can update only the version metadata by passing `--skip-build`.
 
 ## Known Issues
 
-- Live capture on a physical Hantek DSO-2250 never reports a waveform:
-  `GetCaptureState` polling stays at the empty-buffer state, so no channel
-  data is read. Demo mode and the full CTest suite are unaffected. See
-  `HISTORY.md` ("Known issue - live capture on real DSO-2250 hardware
-  reports no waveform") for the investigation and ruled-out causes.
+- None currently tracked.
 
 ## Next Steps
 
-1. Diagnose the live-capture-never-completes issue on real DSO-2250
-   hardware.
-2. Render live and demo waveforms on the display grid.
-3. Implement the two-channel model, timebase, and instrument controls.
+1. Drive the horizontal display window length from the Timebase control using
+   the device's real sample period.
+2. Add a vertical Level slider and per-channel zero-position controls.
+3. Implement cursor-based measurements.
 
 The full goals, constraints, and architecture are documented in
 `WorkingDocs/TECHNICAL_SPECIFICATION.md`.