Updates

flicker_watch.py

@@ -0,0 +1,369 @@
+#!/usr/bin/env python3
+"""
+flicker_watch.py — Continuous LP capture during video on/off cycles.
+
+Operator watches the display.  Script keeps cycling the video stream on/off
+and triggering LP captures in the background.  Files accumulate on the scope
+without being transferred (fast).
+
+Keys (no Enter needed):
+    f  — flicker observed: transfer + archive + analyse recent captures
+    g  — good baseline:    transfer + archive recent captures (no analysis)
+    q  — quit
+
+Captures are organised under data/flicker/{event_ts}/ or data/good/{event_ts}/.
+"""
+
+import json
+import select
+import shutil
+import sys
+import termios
+import time
+import tty
+from datetime import datetime
+from pathlib import Path
+
+import requests
+import vxi11
+
+import ai_mgmt
+from csv_preprocessor import analyze_lp_file
+
+# ---------------------------------------------------------------------------
+# Config
+# ---------------------------------------------------------------------------
+SCOPE_IP    = "192.168.45.4"
+DEVICE_BASE = "http://192.168.45.8:5000"
+VIDEO_URL   = f"{DEVICE_BASE}/video"
+
+DATA_DIR    = Path(__file__).parent / "data"
+FLICKER_DIR = DATA_DIR / "flicker"
+GOOD_DIR    = DATA_DIR / "good"
+
+# LP capture parameters (matched to mipi_test_interactive.py)
+LP_SCALE       = 1e-6        # 1 µs/div → 20 µs window
+LP_POINTS      = 200_000
+LP_TRIG_OFFSET = 9e-6        # 1 µs pre / 19 µs post-trigger
+LP_V_SCALE     = 0.2
+LP_V_OFFSET    = 0.6
+LP_TRIG_LEVEL  = 0.6
+
+CYCLE_S        = 10.0        # seconds video is on per cycle
+TRIG_TIMEOUT_S = 2.0         # per-capture trigger wait
+
+# ---------------------------------------------------------------------------
+# Scope setup
+# ---------------------------------------------------------------------------
+scope = vxi11.Instrument(SCOPE_IP)
+scope.timeout = 30
+
+
+def setup_scope() -> None:
+    """One-shot scope init — channels, math, default trigger."""
+    print("CONFIGURING SCOPE...")
+    cmds = [
+        "*RST", ":RUN", ":STOP",
+        ":CHANnel1:DISPlay ON", ":CHANnel1:INPut DC50", ":CHANnel1:PROBe 19.2",
+        ":CHANnel1:LABel 'CLK+'",
+        ":CHANnel2:DISPlay ON", ":CHANnel2:INPut DC50", ":CHANnel2:PROBe 19.2",
+        ":CHANnel2:LABel 'CLK-'",
+        ":CHANnel3:DISPlay ON", ":CHANnel3:INPut DC50", ":CHANnel3:PROBe 19.2",
+        ":CHANnel3:LABel 'DAT0+'",
+        ":CHANnel4:DISPlay ON", ":CHANnel4:INPut DC50", ":CHANnel4:PROBe 19.2",
+        ":CHANnel4:LABel 'DAT0-'",
+        ":TIMebase:REFerence CENTer",
+        ":TRIGger:MODE EDGE",
+        ":ACQuire:MODE RTIMe", ":ACQuire:INTerpolate ON",
+        ":DISPlay:LAYout STACKED",
+    ]
+    for c in cmds:
+        scope.write(c)
+        time.sleep(0.05)
+    print("SCOPE READY.")
+
+
+def configure_for_lp() -> None:
+    """LP-mode: widen vertical range, falling-edge trigger on Ch3."""
+    for ch in (1, 2, 3, 4):
+        scope.write(f":CHANnel{ch}:SCALe {LP_V_SCALE:.3f}")
+        scope.write(f":CHANnel{ch}:OFFSet {LP_V_OFFSET:.3f}")
+    scope.write(":TRIGger:EDGE:SOURce CHANnel3")
+    scope.write(":TRIGger:EDGE:SLOPe NEGative")
+    scope.write(f":TRIGger:EDGE:LEVel {LP_TRIG_LEVEL:.3f}")
+    scope.write(":TRIGger:SWEep NORMal")
+    scope.write(f":TIMebase:SCALe {LP_SCALE:.3E}")
+    scope.write(f":ACQuire:POINts {LP_POINTS}")
+    scope.write(f":TIMebase:POSition {LP_TRIG_OFFSET:.2E}")
+    time.sleep(0.3)
+
+
+def arm_and_wait(timeout_s: float) -> bool:
+    """:DIGitize + *OPC?. Returns True if trigger fired within timeout."""
+    global scope
+    prev = scope.timeout
+    try:
+        scope.timeout = timeout_s + 2
+        scope.write(":DIGitize")
+        return scope.ask("*OPC?").strip() == "1"
+    except Exception:
+        # Trigger timed out or scope locked up — reconnect.
+        try:
+            scope.close()
+        except Exception:
+            pass
+        time.sleep(1.0)
+        scope = vxi11.Instrument(SCOPE_IP)
+        scope.timeout = 30
+        try:
+            scope.write(":STOP")
+        except Exception:
+            pass
+        return False
+    finally:
+        try:
+            scope.timeout = prev
+        except Exception:
+            pass
+
+
+def save_lp(base_name: str) -> None:
+    """Save Ch1 (CLK+) and Ch3 (DAT0+) as CSV to scope's C:\\TEMP\\."""
+    base = f"C:\\TEMP\\{base_name}"
+    scope.write(f':DISK:SAVE:WAVeform CHANnel1,"{base}_clk.csv",CSV')
+    time.sleep(2.5)
+    scope.write(f':DISK:SAVE:WAVeform CHANnel3,"{base}_dat.csv",CSV')
+    time.sleep(2.5)
+
+
+# ---------------------------------------------------------------------------
+# Non-blocking keyboard
+# ---------------------------------------------------------------------------
+class KeyReader:
+    def __enter__(self):
+        self.fd  = sys.stdin.fileno()
+        self.old = termios.tcgetattr(self.fd)
+        tty.setcbreak(self.fd)
+        return self
+
+    def get_key(self) -> str | None:
+        if select.select([sys.stdin], [], [], 0)[0]:
+            return sys.stdin.read(1).lower()
+        return None
+
+    def __exit__(self, *_):
+        termios.tcsetattr(self.fd, termios.TCSADRAIN, self.old)
+
+
+# ---------------------------------------------------------------------------
+# Video control
+# ---------------------------------------------------------------------------
+def video_start() -> None:
+    try:
+        requests.put(VIDEO_URL,
+                     json={"action": "start", "mode": "static-pink"},
+                     timeout=3)
+    except requests.exceptions.RequestException as e:
+        print(f"  VIDEO START failed: {e}")
+
+
+def video_stop() -> None:
+    try:
+        requests.put(VIDEO_URL, json={"action": "stop"}, timeout=3)
+    except requests.exceptions.RequestException as e:
+        print(f"  VIDEO STOP failed: {e}")
+
+
+# ---------------------------------------------------------------------------
+# Register snapshot from device (DSIM PHY + SN65DSI83)
+# ---------------------------------------------------------------------------
+def fetch_registers_snapshot(target_dir: Path, event_ts: str) -> None:
+    """GET /registers + /sn65_registers, print key indicators, save JSON."""
+    combined: dict = {}
+    for endpoint, key in [("/registers", "dsim"),
+                          ("/sn65_registers", "sn65")]:
+        try:
+            r = requests.get(f"{DEVICE_BASE}{endpoint}", timeout=5)
+            r.raise_for_status()
+            combined[key] = r.json()
+        except Exception as e:
+            print(f"  REGISTERS: {endpoint} failed — {e}")
+            combined[key] = None
+
+    # Quick-look indicators
+    sn65 = combined.get("sn65") or {}
+    regs = sn65.get("registers", {}) if isinstance(sn65, dict) else {}
+    csr_0a = regs.get("csr_0a", {}) or {}
+    csr_e5 = regs.get("csr_e5", {}) or {}
+
+    if csr_0a:
+        pll_str = "LOCKED" if csr_0a.get("pll_lock") else "*** UNLOCKED ***"
+        clk_str = "detected" if csr_0a.get("clk_det") else "NOT detected"
+        print(f"  SN65: PLL {pll_str}  CLK {clk_str}  (CSR 0x0A = {csr_0a.get('value')})")
+
+    if csr_e5:
+        flags = [
+            ("pll_unlock",      "PLL_UNLOCK"),
+            ("cha_sot_bit_err", "SOT_BIT_ERR"),
+            ("cha_llp_err",     "LLP_ERR"),
+            ("cha_ecc_err",     "ECC_ERR"),
+            ("cha_lp_err",      "LP_ERR"),
+            ("cha_crc_err",     "CRC_ERR"),
+        ]
+        active = [label for k, label in flags if csr_e5.get(k)]
+        if active:
+            print(f"  SN65: *** ERROR FLAGS: {', '.join(active)}  "
+                  f"(CSR 0xE5 = {csr_e5.get('value')}) ***")
+        else:
+            print(f"  SN65: no error flags  (CSR 0xE5 = {csr_e5.get('value')})")
+
+    out = target_dir / f"{event_ts}_registers.json"
+    try:
+        out.write_text(json.dumps(combined, indent=2))
+        print(f"  registers → {out.relative_to(DATA_DIR.parent)}")
+    except Exception as e:
+        print(f"  REGISTERS save failed: {e}")
+
+
+# ---------------------------------------------------------------------------
+# Event handling: archive recent captures and (for flicker) analyse
+# ---------------------------------------------------------------------------
+def archive_and_analyse(event: str, since_iso: str) -> None:
+    """
+    Pull every CSV from the scope, move into data/{event}/{event_ts}/.
+    For flicker events, run csv_preprocessor on each LP capture and print a
+    summary table.  Always pulls a register snapshot from the device too.
+    """
+    event_ts = datetime.now().strftime("%Y%m%d_%H%M%S")
+    target   = (FLICKER_DIR if event == "flicker" else GOOD_DIR) / event_ts
+    target.mkdir(parents=True, exist_ok=True)
+
+    print(f"\n  *** {event.upper()} EVENT @ {event_ts} ***")
+
+    # Register snapshot first (fast, before scope transfer which takes longer)
+    fetch_registers_snapshot(target, event_ts)
+
+    print(f"  Transferring scope → {target} ...")
+    try:
+        copied, failed = ai_mgmt.transfer_csv_files()
+    except Exception as e:
+        print(f"  TRANSFER ERROR: {e}")
+        return
+    print(f"  {copied} file(s) transferred  ({failed} failed)")
+
+    # Move just-arrived CSVs out of data/ (flat) into the event folder.
+    moved = 0
+    for csv in DATA_DIR.glob("*.csv"):
+        if csv.is_file():
+            shutil.move(str(csv), target / csv.name)
+            moved += 1
+    print(f"  {moved} file(s) archived to {target.relative_to(DATA_DIR.parent)}")
+
+    if event != "flicker":
+        return
+
+    # Analyse the LP captures we just archived.
+    print("\n  LP analysis (csv_preprocessor):")
+    print("  " + "-" * 78)
+    print(f"  {'file':<46} {'lp_low_ns':>10} {'hs_amp_mV':>10} {'flicker?':>9}")
+    print("  " + "-" * 78)
+
+    lp_files = sorted(target.glob("*_lp_*_dat.csv"))
+    for f in lp_files:
+        try:
+            m = analyze_lp_file(f)
+            lp_low = getattr(m, "lp_low_duration_ns", None)
+            hs_amp = getattr(m, "hs_amp_mV", None)
+            sus    = getattr(m, "flicker_suspect", False)
+            print(f"  {f.name:<46} "
+                  f"{(f'{lp_low:.1f}' if lp_low is not None else '?'):>10} "
+                  f"{(f'{hs_amp:.1f}' if hs_amp is not None else '?'):>10} "
+                  f"{('YES' if sus else 'no'):>9}")
+        except Exception as e:
+            print(f"  {f.name:<46}  ERROR: {e}")
+    print("  " + "-" * 78)
+
+
+# ---------------------------------------------------------------------------
+# Main loop
+# ---------------------------------------------------------------------------
+def main() -> None:
+    DATA_DIR.mkdir(exist_ok=True)
+    FLICKER_DIR.mkdir(exist_ok=True)
+    GOOD_DIR.mkdir(exist_ok=True)
+
+    setup_scope()
+    configure_for_lp()
+
+    print("\n" + "=" * 64)
+    print("  FLICKER WATCH — keys:  f=flicker  g=good  q=quit")
+    print("=" * 64 + "\n")
+
+    cycle = 0
+    try:
+        with KeyReader() as keys:
+            while True:
+                cycle += 1
+                cycle_ts   = datetime.now().strftime("%Y%m%d_%H%M%S")
+                cycle_caps = []
+                cycle_end  = time.time() + CYCLE_S
+
+                video_start()
+                print(f"\n[cycle {cycle:03d}  {cycle_ts}]  video ON  "
+                      f"({CYCLE_S:.0f}s window)", flush=True)
+
+                event = None
+                last_tick = 0.0
+                while time.time() < cycle_end:
+                    seq  = len(cycle_caps) + 1
+                    base = f"{cycle_ts}_lp_c{cycle:03d}_{seq:02d}"
+                    remaining = lambda: max(0, cycle_end - time.time())
+
+                    if arm_and_wait(TRIG_TIMEOUT_S):
+                        try:
+                            save_lp(base)
+                            cycle_caps.append(base)
+                            print(f"  + cap {seq:02d}  [{remaining():4.1f}s left]",
+                                  flush=True)
+                        except Exception as e:
+                            print(f"  save error: {e}", flush=True)
+                    else:
+                        # Trigger timed out — print a heartbeat at most every 2s
+                        if time.time() - last_tick > 2.0:
+                            print(f"  ... waiting for trigger  "
+                                  f"[{remaining():4.1f}s left]", flush=True)
+                            last_tick = time.time()
+
+                    key = keys.get_key()
+                    if key in ("f", "g", "q"):
+                        event = key
+                        break
+
+                video_stop()
+                if event is None:
+                    print(f"[cycle {cycle:03d}]  ended  "
+                          f"({len(cycle_caps)} cap(s), no event)",
+                          flush=True)
+
+                if event == "f":
+                    archive_and_analyse("flicker", cycle_ts)
+                elif event == "g":
+                    archive_and_analyse("good", cycle_ts)
+                elif event == "q":
+                    print("\nQUIT requested.")
+                    break
+
+                # Brief pause before next cycle so video stop settles.
+                time.sleep(0.5)
+
+    except KeyboardInterrupt:
+        print("\nInterrupted (Ctrl+C).")
+    finally:
+        try:
+            video_stop()
+        except Exception:
+            pass
+
+
+if __name__ == "__main__":
+    main()

mipi_test_interactive.py

@@ -1535,37 +1535,30 @@ def run_interactive_test() -> None:
 
 def run_continuous_test() -> None:
     """
-    Continuous LP capture loop — no kiosk restart between iterations.
+    Continuous LP capture loop — pipeline restart per iteration.
 
-    Designed for periodic flicker that repeats roughly every second once the
+    The pipeline (kiosk) is stopped and restarted on every iteration so the
-    display pipeline has started.  The kiosk is started once; the scope
+    scope captures the startup LP-11→LP-01 transition that triggers the flicker.
-    re-arms on the NORMAL LP trigger (VBLANK LP-11 → LP-01 falling edge on
+    The scope is configured and armed BEFORE _start_video() is called so that
-    Ch3) after each capture, effectively sampling one random display frame
+    the first HS burst after pipeline load is always captured.
-    every ~7 s.
 
-    With flicker on ~1/60 frames the expected time to first catch is
+    Sequence per iteration:
-    ~60 × 7 s ≈ 7 minutes of unattended running.
+      1. _stop_video()            — tear down pipeline
+      2. _configure_for_lp()     — set scope channels + trigger (takes ~400 ms)
+      3. _start_video()           — reload pipeline (LP transition fires ~1-2 s later)
+      4. _arm_and_wait()          — scope captures first LP-11→LP-01 on Ch3
+      5. Transfer + LP analysis
+      6. If suspect: LP bit decode + byte comparison vs last clean capture
 
-    When the LP rule-based detector flags a suspect:
+    Press Ctrl+C to stop.  No HTML report is written; raw LP CSVs are kept in data/.
-      • The LP file already on disk (10 GSa/s, 100 ps/sample) is decoded
-        directly using single-ended CLK+/DAT0+ thresholds — no extra capture.
-      • proto_decoder checks the HS-SYNC byte position (misalignment) and the
-        Lane 0 pixel content (corruption).
-      • compare_lp_captures() shows byte-level diffs vs the last clean capture.
-
-    Press Ctrl+C to stop.  No report is written (raw LP/proto CSVs are kept).
     """
     import proto_decoder as _pd
 
     print("\n===== CONTINUOUS CAPTURE MODE =====")
-    print("Kiosk starts once.  Scope re-arms on each VBLANK trigger (no restart).")
+    print("Pipeline restart per iteration — captures startup LP transition.")
-    print("LP-only per iteration; LP bit decode fires directly on LP suspect files.")
+    print("LP bit decode fires automatically on flicker suspects.")
     print("Press Ctrl+C to stop.\n")
 
-    _start_video()
-    print("Waiting 5 s for display pipeline to stabilise...")
-    time.sleep(5.0)
-
     iteration       = 1
     clean_count     = 0
     flicker_count   = 0
@@ -1575,11 +1568,20 @@ def run_continuous_test() -> None:
         while True:
             ts = datetime.now().strftime("%Y%m%d_%H%M%S")
 
-            # ── LP capture ──────────────────────────────────────────────────
+            # ── Stop pipeline, configure scope, then restart pipeline ─────────
+            _stop_video()
+            time.sleep(0.3)
+
+            # Configure scope while pipeline is down — scope will be ready before
+            # the first LP edge fires after _start_video().
             _configure_for_lp()
             _set_timebase(LP_SCALE, LP_POINTS)
             scope.write(f":TIMebase:POSition {LP_TRIG_OFFSET:.2E}")
-            ok = _arm_and_wait(timeout=5)
+
+            _start_video()
+
+            # ── LP capture on startup transition ─────────────────────────────
+            ok = _arm_and_wait(timeout=10)
             scope.write(":TIMebase:POSition 0")
             _restore_hs_config()
 
@@ -1598,7 +1600,7 @@ def run_continuous_test() -> None:
                 iteration += 1
                 continue
 
-            # ── LP analysis (quiet) ──────────────────────────────────────────
+            # ── LP analysis ──────────────────────────────────────────────────
             lp_summaries, suspects = _analyze_lp_files(ts, iteration)
 
             if not suspects:
@@ -1662,7 +1664,7 @@ def main_menu() -> None:
         print("3. CONFIGURE PSU (DEFAULT 24V / 1.5A)")
         print("4. PSU OUTPUT ON/OFF (CH1)")
         print("5. START INTERACTIVE FLICKER TEST  (kiosk restart per iteration)")
-        print("6. START CONTINUOUS CAPTURE TEST   (no restart; LP bit decode on flicker)")
+        print("6. START CONTINUOUS CAPTURE TEST   (no restart; proto decode on flicker)")
         print("7. EXIT")
 
         choice = input("\nSELECT OPTION (1-7): ").strip()

proto_decoder.py

@@ -44,6 +44,9 @@ DSI_DT_RGB888  = 0x3E
 DSI_DT_HSYNC   = 0x21   # short packet — H sync start
 DSI_DT_VSYNC   = 0x01   # short packet — V sync start
 
+# Known-valid DSI data types used in sync-byte validation (VC=0 + DT in this set)
+VALID_DSI_DT = {0x01, 0x11, 0x21, 0x31, 0x08, 0x09, 0x19, 0x29, 0x39, 0x3E}
+
 # MIPI D-PHY HS sync byte (transmitted at start of each HS burst, all-lanes)
 HS_SYNC_BYTE = 0xB8   # 1011_1000 in bit order (LSB first → 00011101 on wire)
 
@@ -149,23 +152,70 @@ def find_hs_start(t_dat, v_dat, t_clk=None, window_ns=500.0, single_ended=False)
     N = len(v_dat)
 
     # --- Single-ended LP path ---
+    # LP-01 + LP-00 + HS-PREPARE + HS-ZERO form a continuous "LP-low" region where
+    # DAT+ < 0.25 V and rolling std < 45 mV.  The LP-low region ends when the first
+    # '1' bit transition in 0xB8 causes rolling std > 45 mV.  Start bit decoding a
+    # few bits BEFORE that spike so the phase search can find complete 0xB8 near byte 0.
     if single_ended:
-        min_lp01 = max(2, int(20.0 / dt_ns))
+        LP11_THRESH_SE = 0.8     # V — LP-11 state (DAT+ high)
-        run = 0
+        LP_LOW_V_SE    = 0.25    # V — LP-01/LP-00/HS-ZERO are all below this
-        lp01_end = None
+        HS_STD_V_SE    = 0.045   # V — rolling std above this → first HS data bit
-        for i in range(N):
+        LP_LOW_MIN_NS  = 5.0     # ns — ignore LP-low runs shorter than this
-            if v_dat[i] < LP_SE_LP01_THRESH_V:
+        LP_MARGIN_NS   = 25.0    # ns — start decode this far before first data bit
-                run += 1
-            else:
-                if run >= min_lp01:
-                    lp01_end = i
-                    break
-                run = 0
 
-        if lp01_end is not None:
+        win_samples = max(10, int(1.0 / dt_ns))
-            skip = max(1, int(50.0 / dt_ns))
+        try:
-            return min(lp01_end + skip, N - 1)
+            from numpy.lib.stride_tricks import sliding_window_view
-        return None
+            rstd = np.zeros(N)
+            wins = sliding_window_view(v_dat, win_samples)
+            rstd[win_samples - 1:win_samples - 1 + len(wins)] = wins.std(axis=-1)
+        except Exception:
+            rstd = np.array([v_dat[max(0, i - win_samples):i + 1].std() for i in range(N)])
+
+        # Find LP-11 end (first sample below LP11_THRESH_SE after LP-11)
+        lp11_end_idx = None
+        in_lp11 = False
+        for i in range(N):
+            if v_dat[i] > LP11_THRESH_SE:
+                in_lp11 = True
+            elif in_lp11:
+                lp11_end_idx = i
+                break
+        if lp11_end_idx is None:
+            return None
+
+        search_end = min(lp11_end_idx + int(2000.0 / dt_ns), N)
+
+        # Find LP-low plateau start: first sustained block of v < LP_LOW_V_SE
+        # AND rstd < HS_STD_V_SE (the LP-11 fall edge has high rstd so we skip it).
+        min_lp_run = max(5, int(LP_LOW_MIN_NS / dt_ns))
+        lp_low_start = None
+        run = 0
+        for i in range(lp11_end_idx, search_end):
+            if v_dat[i] < LP_LOW_V_SE and rstd[i] < HS_STD_V_SE:
+                run += 1
+                if run >= min_lp_run:
+                    lp_low_start = i - run + 1
+                    break
+            else:
+                run = 0
+        if lp_low_start is None:
+            return min(lp11_end_idx + max(1, int(50.0 / dt_ns)), N - 1)
+
+        # Find LP-low plateau end: first rstd > HS_STD_V_SE after the plateau begins.
+        # This is where the first '1' bit in 0xB8 creates a large voltage transition.
+        lp_low_end = None
+        for i in range(lp_low_start, search_end):
+            if rstd[i] > HS_STD_V_SE:
+                lp_low_end = i
+                break
+        if lp_low_end is None:
+            return min(lp_low_start + max(1, int(50.0 / dt_ns)), N - 1)
+
+        # Start decode LP_MARGIN_NS before the first '1' bit of 0xB8 so the 8-phase
+        # search sees the complete sync byte near byte 0.
+        margin = max(1, int(LP_MARGIN_NS / dt_ns))
+        return max(lp_low_start, lp_low_end - margin)
 
     # --- Differential LP-triggered path ---
     # LP-01: D+ = 0 V, D- = high → diff strongly negative (< -0.5 V for ≥ 20 ns)
@@ -379,21 +429,37 @@ def decode_capture(cap_num: int, data_dir: Path, verbose: bool = True):
             print("  ERROR: Too few bits decoded")
         return None
 
-    # Try all 8 bit-phase offsets to handle framing uncertainty from LP-00 CLK edges.
+    # Try all 8 bit-phase offsets. Pass 1: find earliest 0xB8 whose next byte has
-    # LP-00 CLK edges before HS starts produce garbage bits; the correct phase is
+    # VC=0 and a known DSI DT (validated sync). Pass 2 fallback: earliest bare 0xB8.
-    # the one where 0xB8 appears earliest in the byte stream.
+    raw_bytes  = None
-    raw_bytes = None
+    sync_idx   = None
-    sync_idx  = None
     best_phase = 0
-    best_sync  = len(bits)   # sentinel: "not found"
+    best_sync  = len(bits)
+    validated  = False
+
     for phase in range(8):
         rb = bits_to_bytes(bits[phase:])
-        si = find_sync_byte(rb)
+        for i in range(len(rb) - 1):
-        if si is not None and si < best_sync:
+            if rb[i][1] == HS_SYNC_BYTE:
-            best_sync  = si
+                next_byte = rb[i + 1][1]
-            best_phase = phase
+                if (next_byte >> 6) == 0 and (next_byte & 0x3F) in VALID_DSI_DT:
-            raw_bytes  = rb
+                    if i < best_sync:
-            sync_idx   = si
+                        best_sync  = i
+                        best_phase = phase
+                        raw_bytes  = rb
+                        sync_idx   = i
+                        validated  = True
+                    break  # stop at first validated pair for this phase
+
+    if not validated:
+        for phase in range(8):
+            rb = bits_to_bytes(bits[phase:])
+            si = find_sync_byte(rb)
+            if si is not None and si < best_sync:
+                best_sync  = si
+                best_phase = phase
+                raw_bytes  = rb
+                sync_idx   = si
 
     if raw_bytes is None:
         raw_bytes = bits_to_bytes(bits)
@@ -405,7 +471,8 @@ def decode_capture(cap_num: int, data_dir: Path, verbose: bool = True):
     else:
         if verbose:
             t_sync = raw_bytes[sync_idx][0]
-            print(f"  HS sync byte found at byte {sync_idx} (t={t_sync:.0f} ns, bit phase={best_phase})")
+            qual = "validated" if validated else "bare"
+            print(f"  HS sync byte found at byte {sync_idx} (t={t_sync:.0f} ns, bit phase={best_phase}, {qual})")
 
     # Data bytes after sync
     data_bytes = raw_bytes[sync_idx + 1:]  # skip the sync byte itself
@@ -507,8 +574,19 @@ def decode_lp_capture(cap_num: int, data_dir: Path, verbose: bool = True):
         print(f"  HS burst start: {t_hs_start_ns:.0f} ns  "
               f"({hs_duration_us:.1f} µs available of ~18 µs full burst)")
 
+    # Auto-detect HS common mode from the first 200 ns of the HS burst.
+    # CLK+ common mode (~217 mV) and DAT+ common mode (~104 mV on this board) differ;
+    # hard-coding one value for DAT+ breaks the decode.  The median of the HS burst
+    # gives the correct bit threshold for any board without manual calibration.
+    hs_probe_end = min(hs_start_idx + max(1, int(200.0 / dt_ns)), len(v_dat))
+    dat_common_mode = float(np.median(v_dat[hs_start_idx:hs_probe_end]))
+    dat_common_mode = max(0.030, min(0.250, dat_common_mode))  # clamp to 30–250 mV
+
+    if verbose:
+        print(f"  DAT+ HS common mode: {dat_common_mode*1000:.0f} mV  (auto-detected, used as bit threshold)")
+
     bits = decode_bits(t_dat, v_dat, t_clk, v_clk, hs_start_idx,
-                       dat_thresh=LP_SE_DAT_THRESH_V, clk_thresh=LP_SE_CLK_THRESH_V)
+                       dat_thresh=dat_common_mode, clk_thresh=LP_SE_CLK_THRESH_V)
 
     if verbose:
         print(f"  Decoded {len(bits)} bits  ({len(bits)//8} bytes)")
@@ -518,18 +596,35 @@ def decode_lp_capture(cap_num: int, data_dir: Path, verbose: bool = True):
             print("  ERROR: Too few bits decoded")
         return None
 
-    raw_bytes = None
+    raw_bytes  = None
-    sync_idx  = None
+    sync_idx   = None
     best_phase = 0
     best_sync  = len(bits)
+    validated  = False
+
     for phase in range(8):
         rb = bits_to_bytes(bits[phase:])
-        si = find_sync_byte(rb)
+        for i in range(len(rb) - 1):
-        if si is not None and si < best_sync:
+            if rb[i][1] == HS_SYNC_BYTE:
-            best_sync  = si
+                next_byte = rb[i + 1][1]
-            best_phase = phase
+                if (next_byte >> 6) == 0 and (next_byte & 0x3F) in VALID_DSI_DT:
-            raw_bytes  = rb
+                    if i < best_sync:
-            sync_idx   = si
+                        best_sync  = i
+                        best_phase = phase
+                        raw_bytes  = rb
+                        sync_idx   = i
+                        validated  = True
+                    break  # stop at first validated pair for this phase
+
+    if not validated:
+        for phase in range(8):
+            rb = bits_to_bytes(bits[phase:])
+            si = find_sync_byte(rb)
+            if si is not None and si < best_sync:
+                best_sync  = si
+                best_phase = phase
+                raw_bytes  = rb
+                sync_idx   = si
 
     if raw_bytes is None:
         raw_bytes = bits_to_bytes(bits)
@@ -541,7 +636,8 @@ def decode_lp_capture(cap_num: int, data_dir: Path, verbose: bool = True):
     else:
         if verbose:
             t_sync = raw_bytes[sync_idx][0]
-            print(f"  HS sync byte found at byte {sync_idx} (t={t_sync:.0f} ns, bit phase={best_phase})")
+            qual = "validated" if validated else "bare"
+            print(f"  HS sync byte found at byte {sync_idx} (t={t_sync:.0f} ns, bit phase={best_phase}, {qual})")
 
     data_bytes = raw_bytes[sync_idx + 1:]
     header = parse_long_packet_header([b for _, b in data_bytes[:8]])