diff --git a/hardware/t3r_driver.py b/hardware/t3r_driver.py
new file mode 100755
index 0000000..e346301
--- /dev/null
+++ b/hardware/t3r_driver.py
@@ -0,0 +1,287 @@
+"""T3R Stepper Controller driver for ScanEngine-3.
+
+Qt-based driver that owns the serial connection and an internal reader QThread.
+All events arrive as Qt signals; all commands are fire-and-forget writes.
+Create in the main (GUI) thread; no additional thread management required.
+
+Gear train (stage rotation via GR-axis, ch3):
+    Motor  →  10T pinion  →  30T idler  →  125T index gear (stage)
+    Ratio motor:stage = 125/10 = 12.5
+"""
+
+from __future__ import annotations
+
+import threading
+
+import serial
+from PyQt6.QtCore import QObject, QThread, QTimer, pyqtSignal
+
+from . import t3r_protocol as proto
+
+
+class _T3RReader(QThread):
+    """Blocking read loop — runs on its own QThread."""
+
+    frame = pyqtSignal(int, bytes)         # (cmd, payload) for each valid frame
+    finished_reason = pyqtSignal(str)      # "" = clean stop, else I/O error string
+
+    def __init__(self, ser: serial.Serial):
+        super().__init__()
+        self._ser = ser
+        self._running = True
+        self._parser = proto.FrameParser()
+
+    def stop(self):
+        self._running = False
+
+    def run(self):
+        reason = ""
+        while self._running:
+            try:
+                data = self._ser.read(256)
+            except Exception as exc:
+                reason = str(exc) or exc.__class__.__name__
+                break
+            if data:
+                for cmd, payload in self._parser.feed(data):
+                    self.frame.emit(cmd, payload)
+        self.finished_reason.emit(reason)
+
+
+class T3RDriver(QObject):
+    """Qt-based driver for the T3R four-channel stepper controller.
+
+    Usage::
+
+        driver = T3RDriver()
+        driver.handshake_ok.connect(lambda pv, fw, nc: print("connected"))
+        driver.info_updated.connect(on_info)
+        driver.connect("/dev/ttyUSB0")
+        driver.move(0, steps=3200, velocity=8000, accel=4000)
+    """
+
+    CHANNEL_NAMES = ["T-axis (focus)", "Axis 1", "Axis 2", "GR-axis"]
+    GR_AXIS_CH = 3
+
+    # Gear train constants
+    MOTOR_FULL_STEPS_PER_REV = 200
+    GEAR_TEETH_MOTOR = 10
+    GEAR_TEETH_STAGE = 125  # idler is 30T but does not change ratio
+
+    # ── Signals ───────────────────────────────────────────────────────────────
+
+    port_opened = pyqtSignal()              # serial port open; PING sent
+    handshake_ok = pyqtSignal(int, int, int)  # proto_ver, fw_ver, num_channels
+    disconnected = pyqtSignal(str)          # reason ("" = user-initiated)
+
+    info_updated = pyqtSignal(int, object)        # ch, proto.Info
+    drv_status_updated = pyqtSignal(int, object)  # ch, proto.DrvStatus
+    position_updated = pyqtSignal(int, int)       # ch, position (microsteps)
+    motion_done = pyqtSignal(int, int)            # ch, final_position
+    stopped = pyqtSignal(int, int)                # ch, final_position
+    fault_occurred = pyqtSignal(int, int)         # ch, fault_mask
+    ack_received = pyqtSignal(int, int)           # req_cmd, status (0=OK)
+    frame_received = pyqtSignal(int, bytes)       # raw (cmd, payload) for log
+
+    def __init__(self, parent=None):
+        super().__init__(parent)
+        self._ser: serial.Serial | None = None
+        self._reader: _T3RReader | None = None
+        self._write_lock = threading.Lock()
+        self._tearing_down = False
+        self._is_open = False
+
+        self._poll_timer = QTimer(self)
+        self._poll_timer.setInterval(250)
+        self._poll_timer.timeout.connect(self._poll)
+
+    # ── Connection ────────────────────────────────────────────────────────────
+
+    @property
+    def is_open(self) -> bool:
+        return self._is_open
+
+    def connect(self, port: str, baud: int = 115200) -> None:
+        """Open the serial port and start the reader. Emits port_opened on success."""
+        if self._is_open:
+            self.disconnect()
+        try:
+            self._ser = serial.Serial(port, baudrate=baud, timeout=0.05)
+        except Exception as exc:
+            raise RuntimeError(f"Cannot open {port}: {exc}") from exc
+
+        self._tearing_down = False
+        self._is_open = True
+        self._reader = _T3RReader(self._ser)
+        self._reader.frame.connect(self._on_frame)
+        self._reader.finished_reason.connect(self._on_reader_finished)
+        self._reader.start()
+        self.port_opened.emit()
+        self.send_frame(proto.ping())   # handshake; polling starts on PONG
+
+    def disconnect(self) -> None:
+        """Close port and stop polling."""
+        self._teardown("")
+
+    def _on_reader_finished(self, reason: str):
+        if reason:
+            self._teardown(reason)
+
+    def _teardown(self, reason: str):
+        if self._tearing_down or not self._is_open:
+            return
+        self._tearing_down = True
+        self._poll_timer.stop()
+        self._is_open = False
+
+        reader, self._reader = self._reader, None
+        ser, self._ser = self._ser, None
+
+        if reader is not None:
+            reader.stop()
+            if QThread.currentThread() is not reader:
+                reader.wait(1000)
+        if ser is not None:
+            try:
+                ser.close()
+            except Exception:
+                pass
+
+        self.disconnected.emit(reason)
+
+    # ── Sending ───────────────────────────────────────────────────────────────
+
+    def send_frame(self, frame: bytes) -> bool:
+        if not self._is_open or self._ser is None:
+            return False
+        try:
+            with self._write_lock:
+                self._ser.write(frame)
+            return True
+        except Exception as exc:
+            self._teardown(str(exc) or exc.__class__.__name__)
+            return False
+
+    # ── Command API ───────────────────────────────────────────────────────────
+
+    def ping(self):
+        self.send_frame(proto.ping())
+
+    def stop_all(self):
+        self.send_frame(proto.stop_all())
+
+    def enable(self, ch: int):
+        self.send_frame(proto.enable(ch))
+
+    def disable(self, ch: int):
+        self.send_frame(proto.disable(ch))
+
+    def enable_mask(self, mask: int):
+        self.send_frame(proto.enable_mask(mask))
+
+    def set_microstep(self, ch: int, microsteps: int):
+        self.send_frame(proto.set_microstep(ch, microsteps))
+
+    def set_current(self, ch: int, run_ma: int, hold_ma: int, ihold_delay: int):
+        self.send_frame(proto.set_current(ch, run_ma, hold_ma, ihold_delay))
+
+    def move(self, ch: int, steps: int, velocity: int, accel: int):
+        self.send_frame(proto.move(ch, steps, velocity, accel))
+
+    def jog(self, ch: int, velocity: int, accel: int):
+        self.send_frame(proto.jog(ch, velocity, accel))
+
+    def stop(self, ch: int, hard: bool = False):
+        self.send_frame(proto.stop(ch, hard))
+
+    def move_group(self, mask: int, steps: int, velocity: int, accel: int):
+        self.send_frame(proto.move_group(mask, steps, velocity, accel))
+
+    def jog_group(self, mask: int, velocity: int, accel: int):
+        self.send_frame(proto.jog_group(mask, velocity, accel))
+
+    def get_info(self, ch: int):
+        self.send_frame(proto.get_info(ch))
+
+    def get_drv_status(self, ch: int):
+        self.send_frame(proto.get_drv_status(ch))
+
+    def get_position(self, ch: int):
+        self.send_frame(proto.get_position(ch))
+
+    def set_position(self, ch: int, position: int):
+        self.send_frame(proto.set_position(ch, position))
+
+    # ── Rotation helpers ──────────────────────────────────────────────────────
+
+    def steps_for_angle(self, angle_deg: float, microsteps: int) -> int:
+        """Compute GR-axis microsteps needed to rotate the stage by angle_deg."""
+        gear_ratio = self.GEAR_TEETH_STAGE / self.GEAR_TEETH_MOTOR
+        steps_per_stage_rev = self.MOTOR_FULL_STEPS_PER_REV * microsteps * gear_ratio
+        return round(steps_per_stage_rev * angle_deg / 360.0)
+
+    def rotate_stage(self, angle_deg: float, microsteps: int,
+                     velocity: int = 8000, accel: int = 4000):
+        """Move GR-axis by the number of steps that rotate the stage by angle_deg."""
+        steps = self.steps_for_angle(angle_deg, microsteps)
+        self.move(self.GR_AXIS_CH, steps, velocity, accel)
+
+    # ── Polling ───────────────────────────────────────────────────────────────
+
+    def start_polling(self):
+        self._poll_timer.start()
+
+    def stop_polling(self):
+        self._poll_timer.stop()
+
+    def _poll(self):
+        if not self._is_open:
+            return
+        for ch in range(proto.NUM_CHANNELS):
+            self.send_frame(proto.get_info(ch))
+
+    # ── Frame dispatcher ──────────────────────────────────────────────────────
+
+    def _on_frame(self, cmd: int, payload: bytes):
+        self.frame_received.emit(cmd, payload)
+
+        if cmd == proto.RSP_PONG:
+            p = proto.decode_pong(payload)
+            if p:
+                self.handshake_ok.emit(p.proto_ver, p.fw_version, p.num_channels)
+                self.start_polling()
+
+        elif cmd == proto.RSP_ACK:
+            a = proto.decode_ack(payload)
+            if a:
+                self.ack_received.emit(a.req_cmd, a.status)
+
+        elif cmd == proto.RSP_INFO:
+            info = proto.decode_info(payload)
+            if info and 0 <= info.ch < proto.NUM_CHANNELS:
+                self.info_updated.emit(info.ch, info)
+
+        elif cmd == proto.RSP_DRV_STATUS:
+            st = proto.decode_drv_status(payload)
+            if st and 0 <= st.ch < proto.NUM_CHANNELS:
+                self.drv_status_updated.emit(st.ch, st)
+
+        elif cmd == proto.RSP_POSITION:
+            pos = proto.decode_position(payload)
+            if pos and 0 <= pos.ch < proto.NUM_CHANNELS:
+                self.position_updated.emit(pos.ch, pos.position)
+
+        elif cmd == proto.EVT_MOTION_DONE:
+            ev = proto.decode_event_position(payload)
+            if ev and 0 <= ev.ch < proto.NUM_CHANNELS:
+                self.motion_done.emit(ev.ch, ev.position)
+
+        elif cmd == proto.EVT_STOPPED:
+            ev = proto.decode_event_position(payload)
+            if ev and 0 <= ev.ch < proto.NUM_CHANNELS:
+                self.stopped.emit(ev.ch, ev.position)
+
+        elif cmd == proto.EVT_FAULT:
+            ev = proto.decode_fault(payload)
+            if ev and 0 <= ev.ch < proto.NUM_CHANNELS:
+                self.fault_occurred.emit(ev.ch, ev.position)
diff --git a/hardware/t3r_protocol.py b/hardware/t3r_protocol.py
new file mode 100755
index 0000000..ab37229
--- /dev/null
+++ b/hardware/t3r_protocol.py
@@ -0,0 +1,374 @@
+"""T3R binary serial protocol — host-side codec.
+
+A faithful Python port of the wire protocol implemented in ``main/protocol.c``.
+Pure standard library (no PyQt / pyserial), so it can be unit-tested on its own.
+
+Frame layout (all multi-byte fields little-endian):
+
+    +------+------+------+----------------+------+
+    | SOF  | CMD  | LEN  |  PAYLOAD[LEN]   | CRC8 |
+    +------+------+------+----------------+------+
+      0xA5   1 B    1 B       LEN bytes      1 B
+
+CRC8 is CRC-8/SMBUS (poly 0x07, init 0x00) over CMD, LEN and PAYLOAD.
+See PROTOCOL.md for the full catalogue.
+"""
+
+from __future__ import annotations
+
+import struct
+from dataclasses import dataclass
+
+SOF = 0xA5
+PROTO_VERSION = 1
+
+# ---- Requests (host -> device) --------------------------------------------
+CMD_PING = 0x01
+CMD_SET_MICROSTEP = 0x10
+CMD_SET_CURRENT = 0x11
+CMD_ENABLE = 0x12
+CMD_DISABLE = 0x13
+CMD_ENABLE_MASK = 0x14
+CMD_MOVE = 0x20
+CMD_JOG = 0x21
+CMD_STOP = 0x22
+CMD_STOP_ALL = 0x23
+CMD_MOVE_GROUP = 0x24
+CMD_JOG_GROUP = 0x25
+CMD_GET_INFO = 0x30
+CMD_GET_DRV_STATUS = 0x31
+CMD_GET_POSITION = 0x32
+CMD_SET_POSITION = 0x33
+CMD_READ_REG = 0x40
+CMD_WRITE_REG = 0x41
+
+# ---- Responses (device -> host) -------------------------------------------
+RSP_ACK = 0x81
+RSP_PONG = 0x82
+RSP_INFO = 0x83
+RSP_DRV_STATUS = 0x84
+RSP_POSITION = 0x85
+RSP_REG = 0x86
+
+# ---- Asynchronous events (device -> host) ---------------------------------
+EVT_MOTION_DONE = 0xE0
+EVT_STOPPED = 0xE1
+EVT_FAULT = 0xE2
+
+# Human-readable names, used by the log/console.
+CMD_NAMES = {
+    CMD_PING: "PING", CMD_SET_MICROSTEP: "SET_MICROSTEP",
+    CMD_SET_CURRENT: "SET_CURRENT", CMD_ENABLE: "ENABLE", CMD_DISABLE: "DISABLE",
+    CMD_ENABLE_MASK: "ENABLE_MASK",
+    CMD_MOVE: "MOVE", CMD_JOG: "JOG", CMD_STOP: "STOP", CMD_STOP_ALL: "STOP_ALL",
+    CMD_MOVE_GROUP: "MOVE_GROUP", CMD_JOG_GROUP: "JOG_GROUP",
+    CMD_GET_INFO: "GET_INFO", CMD_GET_DRV_STATUS: "GET_DRV_STATUS",
+    CMD_GET_POSITION: "GET_POSITION", CMD_SET_POSITION: "SET_POSITION",
+    CMD_READ_REG: "READ_REG", CMD_WRITE_REG: "WRITE_REG",
+    RSP_ACK: "ACK", RSP_PONG: "PONG", RSP_INFO: "INFO",
+    RSP_DRV_STATUS: "DRV_STATUS", RSP_POSITION: "POSITION", RSP_REG: "REG",
+    EVT_MOTION_DONE: "MOTION_DONE", EVT_STOPPED: "STOPPED", EVT_FAULT: "FAULT",
+}
+
+# ---- ACK status codes ------------------------------------------------------
+STATUS_NAMES = {
+    0x00: "OK", 0x02: "bad length", 0x03: "bad channel", 0x04: "bad parameter",
+    0x05: "busy", 0x06: "SPI comms fault", 0x07: "unknown command",
+}
+
+# ---- INFO.state ------------------------------------------------------------
+STATE_NAMES = {0: "IDLE", 1: "MOVING", 2: "JOGGING", 3: "STOPPING"}
+
+# ---- Fault mask bits -------------------------------------------------------
+FAULT_BITS = [
+    (1 << 0, "SHORT_GND_A"),
+    (1 << 1, "SHORT_GND_B"),
+    (1 << 2, "OVERTEMP"),
+    (1 << 3, "OVERTEMP_WARN"),
+    (1 << 4, "OPEN_LOAD_A"),
+    (1 << 5, "OPEN_LOAD_B"),
+]
+
+MICROSTEPS = [1, 2, 4, 8, 16, 32, 64, 128, 256]
+MAX_VELOCITY = 200_000      # steps/s  (MOTOR_MAX_VELOCITY)
+MAX_ACCEL = 2_000_000       # steps/s2 (MOTOR_MAX_ACCEL)
+NUM_CHANNELS = 4
+
+
+def fault_names(mask: int) -> str:
+    """Render a fault mask as a comma-separated list, or 'none'."""
+    names = [name for bit, name in FAULT_BITS if mask & bit]
+    return ", ".join(names) if names else "none"
+
+
+# ---------------------------------------------------------------------------
+# CRC-8 (poly 0x07, init 0x00) — matches the firmware reference.
+# ---------------------------------------------------------------------------
+
+def crc8(data: bytes) -> int:
+    crc = 0
+    for byte in data:
+        crc ^= byte
+        for _ in range(8):
+            crc = ((crc << 1) ^ 0x07) & 0xFF if crc & 0x80 else (crc << 1) & 0xFF
+    return crc
+
+
+def build_frame(cmd: int, payload: bytes = b"") -> bytes:
+    body = bytes([cmd, len(payload)]) + payload
+    return bytes([SOF]) + body + bytes([crc8(body)])
+
+
+# ---------------------------------------------------------------------------
+# Request encoders — each returns a complete frame ready to write.
+# ---------------------------------------------------------------------------
+
+def ping() -> bytes:
+    return build_frame(CMD_PING)
+
+
+def set_microstep(ch: int, microsteps: int) -> bytes:
+    return build_frame(CMD_SET_MICROSTEP, struct.pack("<BH", ch, microsteps))
+
+
+def set_current(ch: int, run_ma: int, hold_ma: int, ihold_delay: int) -> bytes:
+    return build_frame(CMD_SET_CURRENT,
+                       struct.pack("<BHHB", ch, run_ma, hold_ma, ihold_delay))
+
+
+def enable(ch: int) -> bytes:
+    return build_frame(CMD_ENABLE, bytes([ch]))
+
+
+def disable(ch: int) -> bytes:
+    return build_frame(CMD_DISABLE, bytes([ch]))
+
+
+def enable_mask(mask: int) -> bytes:
+    """Energise exactly the channels in `mask` (bit i = channel i); 0 = all off."""
+    return build_frame(CMD_ENABLE_MASK, bytes([mask & 0x0F]))
+
+
+def move(ch: int, steps: int, velocity: int, accel: int) -> bytes:
+    return build_frame(CMD_MOVE, struct.pack("<BiII", ch, steps, velocity, accel))
+
+
+def jog(ch: int, velocity: int, accel: int) -> bytes:
+    return build_frame(CMD_JOG, struct.pack("<BiI", ch, velocity, accel))
+
+
+def move_group(mask: int, steps: int, velocity: int, accel: int) -> bytes:
+    """Ganged move: every channel in `mask` steps together in lockstep."""
+    return build_frame(CMD_MOVE_GROUP,
+                       struct.pack("<BiII", mask & 0x0F, steps, velocity, accel))
+
+
+def jog_group(mask: int, velocity: int, accel: int) -> bytes:
+    """Ganged jog: every channel in `mask` runs together (velocity 0 = stop)."""
+    return build_frame(CMD_JOG_GROUP,
+                       struct.pack("<BiI", mask & 0x0F, velocity, accel))
+
+
+def stop(ch: int, hard: bool) -> bytes:
+    return build_frame(CMD_STOP, struct.pack("<BB", ch, 1 if hard else 0))
+
+
+def stop_all() -> bytes:
+    return build_frame(CMD_STOP_ALL)
+
+
+def get_info(ch: int) -> bytes:
+    return build_frame(CMD_GET_INFO, bytes([ch]))
+
+
+def get_drv_status(ch: int) -> bytes:
+    return build_frame(CMD_GET_DRV_STATUS, bytes([ch]))
+
+
+def get_position(ch: int) -> bytes:
+    return build_frame(CMD_GET_POSITION, bytes([ch]))
+
+
+def set_position(ch: int, position: int) -> bytes:
+    return build_frame(CMD_SET_POSITION, struct.pack("<Bi", ch, position))
+
+
+def read_reg(ch: int, reg: int) -> bytes:
+    return build_frame(CMD_READ_REG, struct.pack("<BB", ch, reg))
+
+
+def write_reg(ch: int, reg: int, value: int) -> bytes:
+    return build_frame(CMD_WRITE_REG, struct.pack("<BBI", ch, reg, value))
+
+
+# ---------------------------------------------------------------------------
+# Response / event decoders. Each returns a dataclass (or None on bad length).
+# ---------------------------------------------------------------------------
+
+@dataclass
+class Pong:
+    proto_ver: int
+    fw_version: int
+    num_channels: int
+
+
+@dataclass
+class Ack:
+    req_cmd: int
+    status: int
+
+    @property
+    def ok(self) -> bool:
+        return self.status == 0x00
+
+
+@dataclass
+class Info:
+    ch: int
+    state: int
+    position: int
+    velocity: int
+    microsteps: int
+    run_ma: int
+    hold_ma: int
+    enabled: bool
+    comms_ok: bool
+    fault_mask: int
+
+
+@dataclass
+class DrvStatus:
+    ch: int
+    raw: int
+    fault_mask: int
+
+    @property
+    def standstill(self) -> bool:
+        return bool(self.raw & (1 << 31))
+
+    @property
+    def cs_actual(self) -> int:
+        return (self.raw >> 16) & 0x1F
+
+    @property
+    def sg_result(self) -> int:
+        return self.raw & 0x3FF
+
+
+@dataclass
+class Position:
+    ch: int
+    position: int
+
+
+@dataclass
+class Reg:
+    ch: int
+    reg: int
+    value: int
+
+
+def decode_pong(p: bytes):
+    if len(p) < 4:
+        return None
+    proto, fw, nch = struct.unpack_from("<BHB", p, 0)
+    return Pong(proto, fw, nch)
+
+
+def decode_ack(p: bytes):
+    if len(p) < 2:
+        return None
+    return Ack(p[0], p[1])
+
+
+def decode_info(p: bytes):
+    if len(p) < 18:
+        return None
+    (ch, state, pos, vel, micro, run_ma, hold_ma, flags, fault) = \
+        struct.unpack_from("<BBiIHHHBB", p, 0)
+    return Info(ch, state, pos, vel, micro, run_ma, hold_ma,
+                bool(flags & 0x01), bool(flags & 0x02), fault)
+
+
+def decode_drv_status(p: bytes):
+    if len(p) < 6:
+        return None
+    ch, raw, fault = struct.unpack_from("<BIB", p, 0)
+    return DrvStatus(ch, raw, fault)
+
+
+def decode_position(p: bytes):
+    if len(p) < 5:
+        return None
+    ch, pos = struct.unpack_from("<Bi", p, 0)
+    return Position(ch, pos)
+
+
+def decode_reg(p: bytes):
+    if len(p) < 6:
+        return None
+    ch, reg, value = struct.unpack_from("<BBI", p, 0)
+    return Reg(ch, reg, value)
+
+
+def decode_event_position(p: bytes):
+    """MOTION_DONE / STOPPED share the (ch, position) layout."""
+    return decode_position(p)
+
+
+def decode_fault(p: bytes):
+    if len(p) < 2:
+        return None
+    return Position(p[0], p[1])  # reuse (ch, value); value is the fault mask
+
+
+# ---------------------------------------------------------------------------
+# Incremental frame parser — mirrors the firmware byte-wise state machine.
+# ---------------------------------------------------------------------------
+
+class FrameParser:
+    """Feed raw bytes, get back a list of (cmd, payload) for each valid frame.
+
+    Bad-CRC and oversized frames are dropped silently; the parser resyncs on
+    the next SOF, exactly like the device-side parser.
+    """
+
+    MAX_PAYLOAD = 64
+
+    _SOF, _CMD, _LEN, _PAYLOAD, _CRC = range(5)
+
+    def __init__(self):
+        self._state = self._SOF
+        self._cmd = 0
+        self._len = 0
+        self._payload = bytearray()
+
+    def feed(self, data: bytes):
+        out = []
+        for b in data:
+            if self._state == self._SOF:
+                if b == SOF:
+                    self._state = self._CMD
+            elif self._state == self._CMD:
+                self._cmd = b
+                self._state = self._LEN
+            elif self._state == self._LEN:
+                self._len = b
+                self._payload.clear()
+                if b > self.MAX_PAYLOAD:
+                    self._state = self._SOF        # too big: resync
+                elif b == 0:
+                    self._state = self._CRC
+                else:
+                    self._state = self._PAYLOAD
+            elif self._state == self._PAYLOAD:
+                self._payload.append(b)
+                if len(self._payload) >= self._len:
+                    self._state = self._CRC
+            elif self._state == self._CRC:
+                body = bytes([self._cmd, self._len]) + bytes(self._payload)
+                if crc8(body) == b:
+                    out.append((self._cmd, bytes(self._payload)))
+                # else bad CRC: drop, resync
+                self._state = self._SOF
+        return out
diff --git a/t3r_control_panel.py b/t3r_control_panel.py
new file mode 100755
index 0000000..9bd2b74
--- /dev/null
+++ b/t3r_control_panel.py
@@ -0,0 +1,722 @@
+"""T3R Focusing & Rotation Control Panel.
+
+A user-hidable QDialog that provides full control over the T3R four-channel
+stepper controller. Mirrors the functionality of /opt/t3r-firmware/tester.py
+and adds a Stage Rotation section that computes the correct GR-axis step count
+from the physical gear train.
+
+Gear train (ch3 = GR-axis):
+    Motor → 10T pinion → 30T idler → 125T index gear (stage)
+    Motor:stage ratio = 125/10 = 12.5
+
+Usage::
+
+    from t3r_control_panel import T3RControlPanel
+    panel = T3RControlPanel(driver)
+    panel.show()
+    # toggle with panel.setVisible(not panel.isVisible())
+"""
+
+from __future__ import annotations
+
+from PyQt6.QtCore import Qt, QTimer
+from PyQt6.QtGui import QFont
+from PyQt6.QtWidgets import (
+    QCheckBox, QComboBox, QDialog, QDoubleSpinBox, QFrame, QGridLayout,
+    QGroupBox, QHBoxLayout, QLabel, QPlainTextEdit, QPushButton, QScrollArea,
+    QSpinBox, QSplitter, QVBoxLayout, QWidget,
+)
+
+from hardware.t3r_driver import T3RDriver
+import hardware.t3r_protocol as proto
+import serial.tools.list_ports
+
+
+# ── Utilities ─────────────────────────────────────────────────────────────────
+
+def _hline() -> QFrame:
+    line = QFrame()
+    line.setFrameShape(QFrame.Shape.HLine)
+    line.setFrameShadow(QFrame.Shadow.Sunken)
+    return line
+
+
+def _mono_font(size: int = 11) -> QFont:
+    f = QFont("Menlo")
+    f.setStyleHint(QFont.StyleHint.Monospace)
+    f.setPointSize(size)
+    return f
+
+
+def _spin(lo: int, hi: int, val: int) -> QSpinBox:
+    s = QSpinBox()
+    s.setRange(lo, hi)
+    s.setValue(val)
+    s.setGroupSeparatorShown(True)
+    s.setMaximumWidth(130)
+    return s
+
+
+# ── Per-channel panel ─────────────────────────────────────────────────────────
+
+class ChannelPanel(QGroupBox):
+    """Controls and live readouts for one T3R axis."""
+
+    def __init__(self, ch: int, driver: T3RDriver):
+        label = f"Axis {ch} — {T3RDriver.CHANNEL_NAMES[ch]}"
+        super().__init__(label)
+        self.ch = ch
+        self._driver = driver
+        self._build()
+
+        driver.info_updated.connect(self._on_info)
+        driver.drv_status_updated.connect(self._on_drv_status)
+        driver.motion_done.connect(self._on_event_pos)
+        driver.stopped.connect(self._on_event_pos)
+        driver.fault_occurred.connect(self._on_fault_event)
+
+    def _build(self):
+        grid = QGridLayout(self)
+        grid.setVerticalSpacing(4)
+        grid.setHorizontalSpacing(8)
+        row = 0
+
+        # Enable + state + position
+        self.enable_chk = QCheckBox("Enabled")
+        self.enable_chk.toggled.connect(self._on_enable_toggled)
+        grid.addWidget(self.enable_chk, row, 0)
+
+        self.state_lbl = QLabel("—")
+        self.state_lbl.setMinimumWidth(72)
+        grid.addWidget(self.state_lbl, row, 1)
+
+        lbl = QLabel("pos:")
+        lbl.setAlignment(Qt.AlignmentFlag.AlignRight | Qt.AlignmentFlag.AlignVCenter)
+        grid.addWidget(lbl, row, 2)
+        self.pos_lbl = QLabel("0")
+        self.pos_lbl.setFont(_mono_font(13))
+        grid.addWidget(self.pos_lbl, row, 3, 1, 2)
+        row += 1
+
+        self.fault_lbl = QLabel("faults: none")
+        self.fault_lbl.setStyleSheet("color: #2e7d32;")
+        grid.addWidget(self.fault_lbl, row, 0, 1, 3)
+        self.comms_lbl = QLabel("comms: —")
+        grid.addWidget(self.comms_lbl, row, 3, 1, 2)
+        row += 1
+
+        grid.addWidget(_hline(), row, 0, 1, 5); row += 1
+
+        # Configuration
+        grid.addWidget(QLabel("Microsteps"), row, 0)
+        self.micro_combo = QComboBox()
+        for m in proto.MICROSTEPS:
+            self.micro_combo.addItem(str(m), m)
+        self.micro_combo.setCurrentText("16")
+        grid.addWidget(self.micro_combo, row, 1)
+
+        grid.addWidget(QLabel("Run mA"), row, 2)
+        self.run_spin = _spin(0, 3000, 800)
+        grid.addWidget(self.run_spin, row, 3)
+        row += 1
+
+        grid.addWidget(QLabel("ihold delay"), row, 0)
+        self.ihold_spin = _spin(0, 15, 6)
+        grid.addWidget(self.ihold_spin, row, 1)
+
+        grid.addWidget(QLabel("Hold mA"), row, 2)
+        self.hold_spin = _spin(0, 3000, 400)
+        grid.addWidget(self.hold_spin, row, 3)
+
+        apply_btn = QPushButton("Apply config")
+        apply_btn.setToolTip("Send SET_MICROSTEP + SET_CURRENT (channel must be idle)")
+        apply_btn.clicked.connect(self._on_apply_config)
+        grid.addWidget(apply_btn, row, 4)
+        row += 1
+
+        self.achieved_lbl = QLabel("achieved: run —/hold — mA, — µsteps")
+        self.achieved_lbl.setStyleSheet("color: gray;")
+        grid.addWidget(self.achieved_lbl, row, 0, 1, 5)
+        row += 1
+
+        self.drv_lbl = QLabel("driver status: —")
+        self.drv_lbl.setStyleSheet("color: gray;")
+        grid.addWidget(self.drv_lbl, row, 0, 1, 5)
+        row += 1
+
+        grid.addWidget(_hline(), row, 0, 1, 5); row += 1
+
+        # Motion parameters
+        grid.addWidget(QLabel("Max vel (steps/s)"), row, 0)
+        self.vel_spin = _spin(1, proto.MAX_VELOCITY, 8000)
+        grid.addWidget(self.vel_spin, row, 1)
+
+        grid.addWidget(QLabel("Accel (steps/s²)"), row, 2)
+        self.accel_spin = _spin(0, proto.MAX_ACCEL, 4000)
+        grid.addWidget(self.accel_spin, row, 3)
+        row += 1
+
+        # Move
+        grid.addWidget(QLabel("Steps (signed)"), row, 0)
+        self.steps_spin = _spin(-100_000_000, 100_000_000, 3200)
+        grid.addWidget(self.steps_spin, row, 1)
+        move_btn = QPushButton("Move")
+        move_btn.clicked.connect(self._on_move)
+        grid.addWidget(move_btn, row, 2)
+        neg_btn = QPushButton("Move −")
+        neg_btn.clicked.connect(lambda: self._on_move(-1))
+        grid.addWidget(neg_btn, row, 3)
+        pos_btn = QPushButton("Move +")
+        pos_btn.clicked.connect(lambda: self._on_move(+1))
+        grid.addWidget(pos_btn, row, 4)
+        row += 1
+
+        # Jog / stop
+        jogneg = QPushButton("◀ Jog −")
+        jogneg.clicked.connect(lambda: self._on_jog(-1))
+        grid.addWidget(jogneg, row, 0)
+        jogpos = QPushButton("Jog + ▶")
+        jogpos.clicked.connect(lambda: self._on_jog(+1))
+        grid.addWidget(jogpos, row, 1)
+        stop_btn = QPushButton("Stop")
+        stop_btn.clicked.connect(self._on_stop)
+        grid.addWidget(stop_btn, row, 2)
+        self.hard_chk = QCheckBox("hard stop")
+        grid.addWidget(self.hard_chk, row, 3, 1, 2)
+        row += 1
+
+        grid.addWidget(_hline(), row, 0, 1, 5); row += 1
+
+        # Position utilities
+        grid.addWidget(QLabel("Set pos"), row, 0)
+        self.setpos_spin = _spin(-100_000_000, 100_000_000, 0)
+        grid.addWidget(self.setpos_spin, row, 1)
+        setpos_btn = QPushButton("Set")
+        setpos_btn.clicked.connect(self._on_set_position)
+        grid.addWidget(setpos_btn, row, 2)
+        zero_btn = QPushButton("Zero")
+        zero_btn.clicked.connect(lambda: self._driver.set_position(self.ch, 0))
+        grid.addWidget(zero_btn, row, 3)
+        drvst_btn = QPushButton("Driver status")
+        drvst_btn.setToolTip("GET_DRV_STATUS — SPI read, only works while idle")
+        drvst_btn.clicked.connect(lambda: self._driver.get_drv_status(self.ch))
+        grid.addWidget(drvst_btn, row, 4)
+
+        grid.setColumnStretch(4, 1)
+
+    # ── Commands ──────────────────────────────────────────────────────────────
+
+    def _on_enable_toggled(self, checked: bool):
+        if checked:
+            self._driver.enable(self.ch)
+        else:
+            self._driver.disable(self.ch)
+
+    def _on_apply_config(self):
+        micro = self.micro_combo.currentData()
+        self._driver.set_microstep(self.ch, micro)
+        self._driver.set_current(self.ch, self.run_spin.value(),
+                                 self.hold_spin.value(), self.ihold_spin.value())
+
+    def _on_move(self, force_sign: int = 0):
+        steps = self.steps_spin.value()
+        if force_sign:
+            steps = force_sign * abs(steps)
+        self._driver.move(self.ch, steps, self.vel_spin.value(), self.accel_spin.value())
+
+    def _on_jog(self, direction: int):
+        self._driver.jog(self.ch, direction * self.vel_spin.value(), self.accel_spin.value())
+
+    def _on_stop(self):
+        self._driver.stop(self.ch, self.hard_chk.isChecked())
+
+    def _on_set_position(self):
+        self._driver.set_position(self.ch, self.setpos_spin.value())
+
+    # ── Incoming updates ──────────────────────────────────────────────────────
+
+    def _on_info(self, ch: int, info):
+        if ch != self.ch:
+            return
+        self.state_lbl.setText(proto.STATE_NAMES.get(info.state, "?"))
+        self.pos_lbl.setText(f"{info.position:,}")
+        self.achieved_lbl.setText(
+            f"achieved: run {info.run_ma}/hold {info.hold_ma} mA, {info.microsteps} µsteps")
+        self.comms_lbl.setText("comms: OK" if info.comms_ok else "comms: FAIL")
+        self.comms_lbl.setStyleSheet("" if info.comms_ok else "color: #c0392b;")
+        self._set_fault(info.fault_mask)
+        if self.enable_chk.isChecked() != info.enabled:
+            self.enable_chk.blockSignals(True)
+            self.enable_chk.setChecked(info.enabled)
+            self.enable_chk.blockSignals(False)
+
+    def _on_drv_status(self, ch: int, st):
+        if ch != self.ch:
+            return
+        self._set_fault(st.fault_mask)
+        self.drv_lbl.setText(
+            f"driver status: CS_ACTUAL={st.cs_actual}  SG_RESULT={st.sg_result}  "
+            f"{'standstill' if st.standstill else 'moving'}  raw=0x{st.raw:08X}")
+
+    def _on_event_pos(self, ch: int, position: int):
+        if ch == self.ch:
+            self.pos_lbl.setText(f"{position:,}")
+
+    def _on_fault_event(self, ch: int, mask: int):
+        if ch == self.ch:
+            self._set_fault(mask)
+
+    def _set_fault(self, mask: int):
+        names = proto.fault_names(mask)
+        self.fault_lbl.setText(f"faults: {names}")
+        self.fault_lbl.setStyleSheet(
+            "color: #c0392b; font-weight: bold;" if mask else "color: #2e7d32;")
+
+
+# ── Ganged motion panel ───────────────────────────────────────────────────────
+
+class GroupPanel(QGroupBox):
+    """Ganged motion — selected axes step in lockstep."""
+
+    def __init__(self, driver: T3RDriver, log_fn):
+        super().__init__("Ganged / synchronised motion — selected axes move in lockstep")
+        self._driver = driver
+        self._log = log_fn
+        self._axis_chks: list[QCheckBox] = []
+        self._build()
+
+    def _build(self):
+        grid = QGridLayout(self)
+        grid.setVerticalSpacing(4)
+        grid.setHorizontalSpacing(8)
+
+        grid.addWidget(QLabel("Axes:"), 0, 0)
+        axis_box = QHBoxLayout()
+        for i in range(proto.NUM_CHANNELS):
+            chk = QCheckBox(str(i))
+            self._axis_chks.append(chk)
+            axis_box.addWidget(chk)
+        axis_box.addStretch(1)
+        holder = QWidget()
+        holder.setLayout(axis_box)
+        grid.addWidget(holder, 0, 1, 1, 3)
+
+        hold_btn = QPushButton("Energise selected")
+        hold_btn.clicked.connect(self._on_energise)
+        grid.addWidget(hold_btn, 0, 4)
+        rel_btn = QPushButton("Release all")
+        rel_btn.clicked.connect(lambda: self._driver.enable_mask(0))
+        grid.addWidget(rel_btn, 0, 5)
+
+        grid.addWidget(QLabel("Max vel (steps/s)"), 1, 0)
+        self.vel_spin = _spin(1, proto.MAX_VELOCITY, 8000)
+        grid.addWidget(self.vel_spin, 1, 1)
+        grid.addWidget(QLabel("Accel (steps/s²)"), 1, 2)
+        self.accel_spin = _spin(0, proto.MAX_ACCEL, 4000)
+        grid.addWidget(self.accel_spin, 1, 3)
+        grid.addWidget(QLabel("Steps (signed)"), 1, 4)
+        self.steps_spin = _spin(-100_000_000, 100_000_000, 3200)
+        grid.addWidget(self.steps_spin, 1, 5)
+
+        move_btn = QPushButton("Move group")
+        move_btn.clicked.connect(lambda: self._on_move())
+        grid.addWidget(move_btn, 2, 0)
+        neg_btn = QPushButton("Move −")
+        neg_btn.clicked.connect(lambda: self._on_move(-1))
+        grid.addWidget(neg_btn, 2, 1)
+        pos_btn = QPushButton("Move +")
+        pos_btn.clicked.connect(lambda: self._on_move(+1))
+        grid.addWidget(pos_btn, 2, 2)
+        jogneg = QPushButton("◀ Jog −")
+        jogneg.clicked.connect(lambda: self._on_jog(-1))
+        grid.addWidget(jogneg, 2, 3)
+        jogpos = QPushButton("Jog + ▶")
+        jogpos.clicked.connect(lambda: self._on_jog(+1))
+        grid.addWidget(jogpos, 2, 4)
+        stop_btn = QPushButton("Stop group")
+        stop_btn.clicked.connect(self._on_stop)
+        grid.addWidget(stop_btn, 2, 5)
+
+        self.hard_chk = QCheckBox("hard stop")
+        grid.addWidget(self.hard_chk, 3, 5)
+        grid.setColumnStretch(3, 1)
+
+    def _mask(self) -> int:
+        return sum((1 << i) for i, chk in enumerate(self._axis_chks) if chk.isChecked())
+
+    def _require_mask(self) -> int | None:
+        mask = self._mask()
+        if not mask:
+            self._log("No axes selected for ganged motion", "err")
+            return None
+        return mask
+
+    def _on_energise(self):
+        mask = self._require_mask()
+        if mask is not None:
+            self._driver.enable_mask(mask)
+
+    def _on_move(self, force_sign: int = 0):
+        mask = self._require_mask()
+        if mask is None:
+            return
+        steps = self.steps_spin.value()
+        if force_sign:
+            steps = force_sign * abs(steps)
+        self._driver.move_group(mask, steps, self.vel_spin.value(), self.accel_spin.value())
+
+    def _on_jog(self, direction: int):
+        mask = self._require_mask()
+        if mask is None:
+            return
+        self._driver.jog_group(mask, direction * self.vel_spin.value(), self.accel_spin.value())
+
+    def _on_stop(self):
+        mask = self._require_mask()
+        if mask is None:
+            return
+        ch = (mask & -mask).bit_length() - 1
+        self._driver.stop(ch, self.hard_chk.isChecked())
+
+
+# ── Rotation panel ────────────────────────────────────────────────────────────
+
+class RotationPanel(QGroupBox):
+    """Stage rotation via GR-axis (ch3).
+
+    Computes the GR-axis step count from the physical gear train:
+        Motor → 10T pinion → 30T idler → 125T index gear (stage)
+        Ratio = 125/10 = 12.5
+    """
+
+    def __init__(self, driver: T3RDriver):
+        super().__init__(
+            f"Stage Rotation  (GR-axis ch{T3RDriver.GR_AXIS_CH}) — "
+            f"gear: {T3RDriver.GEAR_TEETH_MOTOR}T motor → 30T idler → "
+            f"{T3RDriver.GEAR_TEETH_STAGE}T stage  "
+            f"= {T3RDriver.GEAR_TEETH_STAGE}/{T3RDriver.GEAR_TEETH_MOTOR} ratio"
+        )
+        self._driver = driver
+        self._gr_microsteps = 16  # updated from info_updated signal
+        self._build()
+        driver.info_updated.connect(self._on_info)
+
+    def _build(self):
+        grid = QGridLayout(self)
+        grid.setVerticalSpacing(4)
+        grid.setHorizontalSpacing(8)
+
+        # Microsteps (read-only, tracked from driver)
+        grid.addWidget(QLabel("GR-axis µsteps:"), 0, 0)
+        self.microstep_lbl = QLabel("16 (live from device)")
+        self.microstep_lbl.setStyleSheet("color: gray;")
+        grid.addWidget(self.microstep_lbl, 0, 1)
+
+        # Angle input
+        grid.addWidget(QLabel("Rotate by (°):"), 0, 2)
+        self.angle_spin = QDoubleSpinBox()
+        self.angle_spin.setRange(-360.0, 360.0)
+        self.angle_spin.setSingleStep(1.0)
+        self.angle_spin.setDecimals(3)
+        self.angle_spin.setValue(90.0)
+        self.angle_spin.valueChanged.connect(self._update_steps_display)
+        grid.addWidget(self.angle_spin, 0, 3)
+
+        self.steps_lbl = QLabel("= — steps")
+        self.steps_lbl.setFont(_mono_font(11))
+        grid.addWidget(self.steps_lbl, 0, 4)
+
+        # Velocity / accel
+        grid.addWidget(QLabel("Velocity (steps/s):"), 1, 0)
+        self.vel_spin = _spin(1, proto.MAX_VELOCITY, 8000)
+        grid.addWidget(self.vel_spin, 1, 1)
+
+        grid.addWidget(QLabel("Accel (steps/s²):"), 1, 2)
+        self.accel_spin = _spin(0, proto.MAX_ACCEL, 4000)
+        grid.addWidget(self.accel_spin, 1, 3)
+
+        # Preset angles for N-angle scans
+        grid.addWidget(QLabel("Quick presets:"), 2, 0)
+        presets = QHBoxLayout()
+        for n in (2, 4, 6, 8, 12):
+            btn = QPushButton(f"360/{n}")
+            btn.setToolTip(f"{360/n:.3f}° — rotate for {n}-angle scan")
+            btn.clicked.connect(lambda _, ang=360.0/n: self.angle_spin.setValue(ang))
+            presets.addWidget(btn)
+        presets.addStretch(1)
+        presets_w = QWidget()
+        presets_w.setLayout(presets)
+        grid.addWidget(presets_w, 2, 1, 1, 3)
+
+        # Execute
+        rotate_btn = QPushButton("Rotate Stage")
+        rotate_btn.setStyleSheet(
+            "QPushButton { background: #1565c0; color: white; font-weight: bold; padding: 4px 14px; }"
+            "QPushButton:disabled { background: #90a4ae; }")
+        rotate_btn.clicked.connect(self._on_rotate)
+        grid.addWidget(rotate_btn, 2, 4)
+
+        grid.setColumnStretch(4, 1)
+        self._update_steps_display()
+
+    def _on_info(self, ch: int, info):
+        if ch != T3RDriver.GR_AXIS_CH:
+            return
+        self._gr_microsteps = info.microsteps
+        self.microstep_lbl.setText(f"{info.microsteps} µsteps (from device)")
+        self._update_steps_display()
+
+    def _update_steps_display(self):
+        steps = self._driver.steps_for_angle(self.angle_spin.value(), self._gr_microsteps)
+        self.steps_lbl.setText(f"= {steps:,} steps")
+
+    def _on_rotate(self):
+        self._driver.rotate_stage(
+            self.angle_spin.value(), self._gr_microsteps,
+            self.vel_spin.value(), self.accel_spin.value())
+
+
+# ── Main dialog ───────────────────────────────────────────────────────────────
+
+class T3RControlPanel(QDialog):
+    """User-hidable T3R control window.
+
+    Pass a T3RDriver instance. The panel connects to its signals and forwards
+    commands via its API. Connection management (port open/close) is handled
+    inside the panel itself.
+    """
+
+    def __init__(self, driver: T3RDriver, parent=None):
+        super().__init__(parent)
+        self.setWindowTitle("T3R Stepper Controller")
+        self.setWindowFlags(
+            Qt.WindowType.Window
+            | Qt.WindowType.WindowCloseButtonHint
+            | Qt.WindowType.WindowMinimizeButtonHint
+        )
+        self._driver = driver
+        self._build()
+        self._connect_driver_signals()
+        self._set_controls_enabled(False)
+
+    # ── Construction ──────────────────────────────────────────────────────────
+
+    def _build(self):
+        outer = QVBoxLayout(self)
+
+        outer.addLayout(self._build_connection_bar())
+
+        splitter = QSplitter(Qt.Orientation.Vertical)
+
+        panels_host = QWidget()
+        vbox = QVBoxLayout(panels_host)
+        self.group_panel = GroupPanel(self._driver, self._log)
+        vbox.addWidget(self.group_panel)
+
+        grid_holder = QWidget()
+        grid = QGridLayout(grid_holder)
+        grid.setContentsMargins(0, 0, 0, 0)
+        self.channel_panels: list[ChannelPanel] = []
+        for ch in range(proto.NUM_CHANNELS):
+            p = ChannelPanel(ch, self._driver)
+            self.channel_panels.append(p)
+            grid.addWidget(p, ch // 2, ch % 2)
+        vbox.addWidget(grid_holder)
+
+        self.rotation_panel = RotationPanel(self._driver)
+        vbox.addWidget(self.rotation_panel)
+
+        scroll = QScrollArea()
+        scroll.setWidgetResizable(True)
+        scroll.setWidget(panels_host)
+        splitter.addWidget(scroll)
+
+        splitter.addWidget(self._build_log())
+        splitter.setStretchFactor(0, 3)
+        splitter.setStretchFactor(1, 1)
+        outer.addWidget(splitter, 1)
+
+        self.resize(1100, 950)
+
+    def _build_connection_bar(self) -> QHBoxLayout:
+        bar = QHBoxLayout()
+        bar.addWidget(QLabel("Port:"))
+        self.port_combo = QComboBox()
+        self.port_combo.setMinimumWidth(280)
+        bar.addWidget(self.port_combo)
+
+        refresh_btn = QPushButton("⟳")
+        refresh_btn.setMaximumWidth(36)
+        refresh_btn.setToolTip("Rescan serial ports")
+        refresh_btn.clicked.connect(self._refresh_ports)
+        bar.addWidget(refresh_btn)
+
+        self.connect_btn = QPushButton("Connect")
+        self.connect_btn.clicked.connect(self._toggle_connect)
+        bar.addWidget(self.connect_btn)
+
+        self.conn_lbl = QLabel("disconnected")
+        bar.addWidget(self.conn_lbl)
+        bar.addStretch(1)
+
+        self.ping_btn = QPushButton("Ping")
+        self.ping_btn.setEnabled(False)
+        self.ping_btn.clicked.connect(self._driver.ping)
+        bar.addWidget(self.ping_btn)
+
+        self.fw_lbl = QLabel("")
+        bar.addWidget(self.fw_lbl)
+
+        self.stopall_btn = QPushButton("STOP ALL")
+        self.stopall_btn.setEnabled(False)
+        self.stopall_btn.setStyleSheet(
+            "QPushButton { background:#c0392b; color:white; font-weight:bold; padding:4px 14px; }"
+            "QPushButton:disabled { background:#e8a39b; }")
+        self.stopall_btn.clicked.connect(self._driver.stop_all)
+        bar.addWidget(self.stopall_btn)
+        return bar
+
+    def _build_log(self) -> QWidget:
+        box = QWidget()
+        v = QVBoxLayout(box)
+        v.setContentsMargins(0, 0, 0, 0)
+        head = QHBoxLayout()
+        head.addWidget(QLabel("Log"))
+        head.addStretch(1)
+        self.rawlog_chk = QCheckBox("Log raw frames")
+        head.addWidget(self.rawlog_chk)
+        clear_btn = QPushButton("Clear")
+        clear_btn.clicked.connect(lambda: self.log_view.clear())
+        head.addWidget(clear_btn)
+        v.addLayout(head)
+        self.log_view = QPlainTextEdit()
+        self.log_view.setReadOnly(True)
+        self.log_view.setMaximumBlockCount(2000)
+        self.log_view.setFont(_mono_font(11))
+        v.addWidget(self.log_view)
+        return box
+
+    # ── Driver signal wiring ──────────────────────────────────────────────────
+
+    def _connect_driver_signals(self):
+        self._driver.port_opened.connect(self._on_port_opened)
+        self._driver.handshake_ok.connect(self._on_handshake_ok)
+        self._driver.disconnected.connect(self._on_disconnected)
+        self._driver.ack_received.connect(self._on_ack)
+        self._driver.motion_done.connect(self._on_motion_done)
+        self._driver.stopped.connect(self._on_stopped)
+        self._driver.fault_occurred.connect(self._on_fault)
+        self._driver.frame_received.connect(self._on_raw_frame)
+
+    # ── Connection control ────────────────────────────────────────────────────
+
+    def _refresh_ports(self):
+        current = self.port_combo.currentText()
+        self.port_combo.clear()
+        ports = list(serial.tools.list_ports.comports())
+
+        def score(p):
+            text = f"{p.description} {p.manufacturer or ''} {p.product or ''}".lower()
+            hints = ("esp32", "jtag", "espressif", "usb serial", "cp210", "ch340", "cdc")
+            return -sum(h in text for h in hints)
+
+        ports.sort(key=score)
+        for p in ports:
+            self.port_combo.addItem(f"{p.device} — {p.description or p.device}", p.device)
+        if self.port_combo.count() == 0:
+            self.port_combo.addItem("(no serial ports found)", None)
+        elif current:
+            idx = self.port_combo.findText(current, Qt.MatchFlag.MatchStartsWith)
+            if idx >= 0:
+                self.port_combo.setCurrentIndex(idx)
+
+    def _toggle_connect(self):
+        if self._driver.is_open:
+            self._driver.disconnect()
+            return
+        port = self.port_combo.currentData()
+        if not port:
+            self._log("No serial port selected", "err")
+            return
+        try:
+            self._driver.connect(port)
+        except Exception as exc:
+            self._log(f"Connect failed: {exc}", "err")
+            self.conn_lbl.setText("connect failed")
+
+    # ── Driver event handlers ─────────────────────────────────────────────────
+
+    def _on_port_opened(self):
+        self.conn_lbl.setText("opening…")
+        self.connect_btn.setText("Disconnect")
+        self.port_combo.setEnabled(False)
+        self._log(f"Port opened, sending PING…", "evt")
+
+    def _on_handshake_ok(self, proto_ver: int, fw_ver: int, num_ch: int):
+        self.conn_lbl.setText("connected")
+        self.fw_lbl.setText(
+            f"proto v{proto_ver}, fw {fw_ver >> 8}.{fw_ver & 0xFF}, {num_ch} ch")
+        self._log(f"PONG: proto v{proto_ver}, fw 0x{fw_ver:04X}, {num_ch} ch", "rx")
+        self._set_controls_enabled(True)
+
+    def _on_disconnected(self, reason: str):
+        self.conn_lbl.setText(f"disconnected ({reason})" if reason else "disconnected")
+        self.connect_btn.setText("Connect")
+        self.port_combo.setEnabled(True)
+        self.fw_lbl.setText("")
+        self._set_controls_enabled(False)
+        if reason:
+            self._log(f"Disconnected: {reason}", "err")
+        else:
+            self._log("Disconnected", "evt")
+
+    def _on_ack(self, req_cmd: int, status: int):
+        name = proto.CMD_NAMES.get(req_cmd, f"0x{req_cmd:02X}")
+        status_name = proto.STATUS_NAMES.get(status, f"0x{status:02X}")
+        if status != 0:
+            self._log(f"ACK {name} → {status_name}", "rx")
+        elif self.rawlog_chk.isChecked():
+            self._log(f"ACK {name} → OK", "rx")
+
+    def _on_motion_done(self, ch: int, position: int):
+        name = T3RDriver.CHANNEL_NAMES[ch] if ch < len(T3RDriver.CHANNEL_NAMES) else f"ch{ch}"
+        self._log(f"MOTION_DONE {name} @ {position:,}", "evt")
+
+    def _on_stopped(self, ch: int, position: int):
+        name = T3RDriver.CHANNEL_NAMES[ch] if ch < len(T3RDriver.CHANNEL_NAMES) else f"ch{ch}"
+        self._log(f"STOPPED {name} @ {position:,}", "evt")
+
+    def _on_fault(self, ch: int, mask: int):
+        name = T3RDriver.CHANNEL_NAMES[ch] if ch < len(T3RDriver.CHANNEL_NAMES) else f"ch{ch}"
+        self._log(f"FAULT {name}: {proto.fault_names(mask)}", "err")
+
+    def _on_raw_frame(self, cmd: int, payload: bytes):
+        if self.rawlog_chk.isChecked():
+            frame = proto.build_frame(cmd, payload)
+            self._log(frame.hex(" "), "rx")
+
+    def _set_controls_enabled(self, on: bool):
+        self.ping_btn.setEnabled(on)
+        self.stopall_btn.setEnabled(on)
+        self.group_panel.setEnabled(on)
+        self.rotation_panel.setEnabled(on)
+        for p in self.channel_panels:
+            p.setEnabled(on)
+
+    # ── Logging ───────────────────────────────────────────────────────────────
+
+    def _log(self, msg: str, kind: str = ""):
+        prefix = {"tx": "→ ", "rx": "← ", "evt": "● ", "err": "! "}.get(kind, "  ")
+        self.log_view.appendPlainText(prefix + msg)
+
+    # ── Lifecycle ─────────────────────────────────────────────────────────────
+
+    def showEvent(self, event):
+        super().showEvent(event)
+        if self.port_combo.count() == 0:
+            self._refresh_ports()
+
+    def closeEvent(self, event):
+        # Hide instead of destroy so the window can be re-shown.
+        event.ignore()
+        self.hide()