More attempts at getting this usb dectalk working.

README.md

@@ -81,13 +81,16 @@ Fenrir is a Linux screen reader. Linux is the only officially supported platform
    - espeak or espeak-ng (or any TTS command)
 3. **dectalkDriver** - Serial DECtalk-compatible hardware speech driver
    - RPITalk gadget mode or a DECtalk-compatible serial device
-4. **litetalkDriver** - Serial LiteTalk-compatible hardware speech driver
+4. **dectalkUsbDriver** - Native Access Solutions DECtalk USB driver
+   - USB ID `0dd0:2001`
+   - PyUSB and a libusb backend
+5. **litetalkDriver** - Serial LiteTalk-compatible hardware speech driver
    - RPITalk gadget mode or a LiteTalk-compatible serial device
-5. **doubletalkDriver** - Serial DoubleTalk LT-compatible hardware speech driver
+6. **doubletalkDriver** - Serial DoubleTalk LT-compatible hardware speech driver
    - DoubleTalk LT; does not support the internal DoubleTalk PC card
-6. **tripletalkDriver** - Serial TripleTalk-compatible hardware speech driver
+7. **tripletalkDriver** - Serial TripleTalk-compatible hardware speech driver
    - External DB9 serial TripleTalk devices, or USB models that expose a tty serial device
-7. **debugDriver** - Debug speech driver for testing
+8. **debugDriver** - Debug speech driver for testing
    - No dependencies
 
 
@@ -459,15 +462,22 @@ setting <action> [parameters]
 - `speech#volume=0.1-1.0` - Speech volume
 - `speech#voice=voice_name` - Voice selection (e.g., "en-us+f3")
 - `speech#module=module_name` - TTS module (e.g., "espeak-ng")
-- `speech#driver=driver_name` - Speech driver (speechdDriver/genericDriver/dectalkDriver/litetalkDriver/doubletalkDriver/tripletalkDriver)
+- `speech#driver=driver_name` - Speech driver (speechdDriver/genericDriver/dectalkDriver/dectalkUsbDriver/litetalkDriver/doubletalkDriver/tripletalkDriver)
 - `speech#hardware_device=/dev/ttyS0` - Hardware synth serial device for dectalkDriver/litetalkDriver
 - `speech#hardware_baud_rate=9600` - Hardware synth serial baud rate
 - `speech#history_size=50` - Number of spoken items kept in runtime speech history
 
+The native Access Solutions DECtalk USB, USB ID `0dd0:2001`, uses
+`dectalkUsbDriver`. It is autodetected and does not use
+`speech#hardware_device` or `speech#hardware_baud_rate`. Install PyUSB and a
+libusb backend first. From a source checkout, use
+`python3 -m pip install '.[dectalk_usb]'`; distributions may package PyUSB as
+`python3-usb` or `python-pyusb`. Root-run Fenrir can access the device directly.
+A non-root Fenrir process needs a local udev rule granting its account
+read/write access to `0dd0:2001`; do not make the device world-writable. Other
 USB hardware synths are supported only when Linux exposes them as a serial tty
-such as `/dev/ttyACM0` or `/dev/ttyUSB0`. A USB-only TripleTalk with no tty
-device would require a separate USB protocol driver. Use an explicit
-`speech#hardware_device` path for hardware speech.
+such as `/dev/ttyACM0` or `/dev/ttyUSB0`. Use an explicit
+`speech#hardware_device` path for serial hardware speech.
 - `speech#auto_read_incoming=True/False` - Auto-read new text
 
 *Sound Settings:*

config/settings/settings.conf

@@ -36,10 +36,12 @@ progress_monitoring=True
 enabled=True
 
 # Select speech driver, options are speechdDriver, genericDriver,
-# dectalkDriver, litetalkDriver, doubletalkDriver, or tripletalkDriver:
+# dectalkDriver, dectalkUsbDriver, litetalkDriver, doubletalkDriver,
+# or tripletalkDriver:
 driver=speechdDriver
 #driver=genericDriver
 #driver=dectalkDriver
+#driver=dectalkUsbDriver
 #driver=litetalkDriver
 #driver=doubletalkDriver
 #driver=tripletalkDriver
@@ -77,6 +79,7 @@ volume=1.0
 
 # Hardware speech synthesizer serial device.
 # Used by dectalkDriver, litetalkDriver, doubletalkDriver, and tripletalkDriver.
+# dectalkUsbDriver autodetects the Access Solutions device and ignores this.
 # USB serial devices are supported if Linux exposes them as /dev/ttyACM*
 # or /dev/ttyUSB*. USB-only synths with no tty device need a separate driver.
 # Set an explicit device for hardware speech.

docs/fenrir.1

@@ -242,6 +242,8 @@ genericDriver - Command-line TTS (espeak, etc.)
 .IP \[bu] 4
 dectalkDriver - DECtalk-compatible serial hardware speech
 .IP \[bu] 4
+dectalkUsbDriver - Native Access Solutions DECtalk USB hardware speech
+.IP \[bu] 4
 litetalkDriver - LiteTalk-compatible serial hardware speech
 .IP \[bu] 4
 doubletalkDriver - DoubleTalk LT-compatible serial hardware speech

docs/fenrir.adoc

@@ -1551,9 +1551,11 @@ enabled=True
 Values: on=`+True+`, off=`+False+`
 
 # Select speech driver, options are speechdDriver (default),
-genericDriver, dectalkDriver, litetalkDriver, doubletalkDriver or tripletalkDriver: driver=speechdDriver
+genericDriver, dectalkDriver, dectalkUsbDriver, litetalkDriver,
+doubletalkDriver or tripletalkDriver: driver=speechdDriver
 #driver=genericDriver
 #driver=dectalkDriver
+#driver=dectalkUsbDriver
 #driver=litetalkDriver
 #driver=doubletalkDriver
 #driver=tripletalkDriver
@@ -1684,7 +1686,7 @@ the pico module:
 language=de-DE
 ....
 
-Hardware speech drivers use a serial device. Set an explicit path.
+Serial hardware speech drivers use a serial device. Set an explicit path.
 
 ....
 hardware_device=/dev/ttyACM0
@@ -1700,9 +1702,14 @@ hardware_baud_rate=9600
 
 The `+doubletalkDriver+` targets DoubleTalk LT-style serial devices. It does
 not support the internal DoubleTalk PC ISA card.
-USB hardware speech synthesizers are supported only when Linux exposes them as
-a serial tty such as `+/dev/ttyACM0+` or `+/dev/ttyUSB0+`. USB-only TripleTalk
-models with no tty device need a separate driver.
+The `+dectalkUsbDriver+` autodetects the native Access Solutions DECtalk USB,
+USB ID `+0dd0:2001+`. It requires PyUSB and a libusb backend and ignores the
+serial device and baud-rate settings. From a source checkout, install the USB
+dependencies with `+python3 -m pip install '.[dectalk_usb]'+`. A non-root
+Fenrir process needs a local udev rule granting its account read/write access
+to `+0dd0:2001+`; do not make the device world-writable. Other USB hardware
+speech synthesizers are supported only when Linux exposes them as a serial tty
+such as `+/dev/ttyACM0+` or `+/dev/ttyUSB0+`.
 
 Read new text as it occurs auto_read_incoming=True Values: on=`+True+`,
 off=`+False+`

docs/user.md

@@ -340,18 +340,24 @@ status formats, which change too frequently to support reliably.
 - **speechdDriver** - Speech-dispatcher (recommended)
 - **genericDriver** - Command-line TTS (espeak, etc.)
 - **dectalkDriver** - Serial DECtalk-compatible hardware speech
+- **dectalkUsbDriver** - Native Access Solutions DECtalk USB (`0dd0:2001`)
 - **litetalkDriver** - Serial LiteTalk-compatible hardware speech
 - **doubletalkDriver** - Serial DoubleTalk LT-compatible hardware speech
 - **tripletalkDriver** - Serial TripleTalk-compatible hardware speech
 
-For hardware speech, set `speech#hardware_device` to an explicit serial path.
+For serial hardware speech, set `speech#hardware_device` to an explicit path.
 RPITalk gadget mode usually appears as `/dev/ttyACM0`; USB serial adapters
 usually appear as `/dev/ttyUSB0`; built-in serial ports may be `/dev/ttyS0`.
 The default baud rate is `9600`. `doubletalkDriver` targets
 DoubleTalk LT-style serial devices, not the internal DoubleTalk PC ISA card.
-USB TripleTalk devices work only if Linux exposes them as a serial tty such as
-`/dev/ttyACM0` or `/dev/ttyUSB0`; USB-only models with no tty device need a
-separate driver.
+The `dectalkUsbDriver` autodetects the native Access Solutions DECtalk USB and
+ignores both serial settings. It requires PyUSB and a libusb backend. From a
+source checkout, install them with
+`python3 -m pip install '.[dectalk_usb]'`. A non-root Fenrir process also needs
+a local udev rule granting its account read/write access to USB ID
+`0dd0:2001`; do not make the device world-writable. USB TripleTalk devices work
+only if Linux exposes them as a serial tty such as `/dev/ttyACM0` or
+`/dev/ttyUSB0`.
 
 ### Sound Drivers  
 - **genericDriver** - Sox-based (default)

docs/user.txt

@@ -878,10 +878,11 @@ Turn speech on or off:
   enabled=True
 Values: on=''True'', off=''False''
 
-# Select speech driver, options are speechdDriver (default), genericDriver, dectalkDriver, litetalkDriver, doubletalkDriver or tripletalkDriver:
+# Select speech driver, options are speechdDriver (default), genericDriver, dectalkDriver, dectalkUsbDriver, litetalkDriver, doubletalkDriver or tripletalkDriver:
 driver=speechdDriver
 #driver=genericDriver
 #driver=dectalkDriver
+#driver=dectalkUsbDriver
 #driver=litetalkDriver
 #driver=doubletalkDriver
 #driver=tripletalkDriver
@@ -894,6 +895,7 @@ Available Drivers:
   * ''genericDriver'' using the generic driver, for Fenrir <1.5 this is not available
   * ''speechdDriver'' using speech-dispatcher, for Fenrir <1.5 just use ''speechd''
   * ''dectalkDriver'' using DECtalk-compatible serial hardware or RPITalk
+  * ''dectalkUsbDriver'' using the native Access Solutions DECtalk USB
   * ''litetalkDriver'' using LiteTalk-compatible serial hardware or RPITalk
   * ''doubletalkDriver'' using DoubleTalk LT-compatible serial hardware
   * ''tripletalkDriver'' using TripleTalk-compatible serial hardware
@@ -927,7 +929,7 @@ Select the language you want Fenrir to use.
   language=english-us
 Values: Text, see your TTS synths documentation what is available.
 
-Hardware speech drivers use a serial device. Set an explicit path.
+Serial hardware speech drivers use a serial device. Set an explicit path.
   hardware_device=/dev/ttyACM0
   hardware_device=/dev/ttyUSB0
   hardware_device=/dev/ttyS0
@@ -936,7 +938,7 @@ Hardware speech drivers use 9600 baud by default.
   hardware_baud_rate=9600
 
 The doubletalkDriver targets DoubleTalk LT-style serial devices. It does not support the internal DoubleTalk PC ISA card.
-USB hardware speech synthesizers are supported only when Linux exposes them as a serial tty such as /dev/ttyACM0 or /dev/ttyUSB0. USB-only TripleTalk models with no tty device need a separate driver.
+The dectalkUsbDriver autodetects the native Access Solutions DECtalk USB, USB ID 0dd0:2001. It requires PyUSB and a libusb backend and ignores the serial device and baud-rate settings. Other USB hardware speech synthesizers are supported only when Linux exposes them as a serial tty such as /dev/ttyACM0 or /dev/ttyUSB0.
 
 Read new text as it occurs
 auto_read_incoming=True

setup.py

@@ -106,6 +106,7 @@ setup(
         "pyte>=0.7.0",
     ],
     extras_require={
+        "dectalk_usb": ["pyusb>=1.2.1"],
         "x11": ["python-xlib>=0.33"],
     },
 )

src/fenrirscreenreader/core/settingsManager.py

@@ -521,6 +521,7 @@ class SettingsManager:
                     "speechdDriver",
                     "genericDriver",
                     "dectalkDriver",
+                    "dectalkUsbDriver",
                     "doubletalkDriver",
                     "litetalkDriver",
                     "tripletalkDriver",

src/fenrirscreenreader/speechDriver/dectalkUsbDriver.py

@@ -0,0 +1,202 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+# Fenrir TTY screen reader
+# By Chrys, Storm Dragon, and contributors.
+
+import threading
+
+from fenrirscreenreader.core import debug
+from fenrirscreenreader.speechDriver import dectalkDriver
+
+
+class driver(dectalkDriver.driver):
+    vendor_id = 0x0DD0
+    product_id = 0x2001
+    interface = 0
+    speech_endpoint = 0x02
+    immediate_endpoint = 0x04
+    packet_size = 64
+    write_timeout = 1000
+
+    def initialize(self, environment):
+        self.env = environment
+        self._is_initialized = False
+        self.usb_device = None
+        self.usb_core = None
+        self.usb_util = None
+        self.immediate_lock = threading.Lock()
+        self._debug(
+            "DECtalk USB initialize: requested_device=0dd0:2001",
+            debug.DebugLevel.INFO,
+            on_any_level=True,
+        )
+
+        try:
+            self.usb_core, self.usb_util = self._load_usb_modules()
+        except ImportError as error:
+            self._debug(
+                f"DECtalk USB requires PyUSB: {error}",
+                debug.DebugLevel.ERROR,
+                on_any_level=True,
+            )
+            raise RuntimeError("DECtalk USB requires PyUSB") from error
+
+        try:
+            usb_device = self.usb_core.find(
+                idVendor=self.vendor_id,
+                idProduct=self.product_id,
+            )
+        except (
+            self.usb_core.NoBackendError,
+            self.usb_core.USBError,
+            OSError,
+        ) as error:
+            self._debug(
+                f"DECtalk USB discovery failed: {error}",
+                debug.DebugLevel.ERROR,
+                on_any_level=True,
+            )
+            raise RuntimeError(
+                f"DECtalk USB discovery failed: {error}"
+            ) from error
+        if usb_device is None:
+            self._debug(
+                "DECtalk USB device 0dd0:2001 was not found",
+                debug.DebugLevel.ERROR,
+                on_any_level=True,
+            )
+            raise RuntimeError("DECtalk USB device 0dd0:2001 was not found")
+
+        try:
+            try:
+                usb_device.get_active_configuration()
+            except self.usb_core.USBError:
+                usb_device.set_configuration()
+            self.usb_util.claim_interface(usb_device, self.interface)
+        except (self.usb_core.USBError, OSError) as error:
+            self._dispose_usb_device(usb_device)
+            self._debug(
+                f"DECtalk USB open failed: {error}",
+                debug.DebugLevel.ERROR,
+                on_any_level=True,
+            )
+            raise RuntimeError(f"DECtalk USB open failed: {error}") from error
+
+        self.usb_device = usb_device
+        self._is_initialized = True
+        self._stop_worker = False
+        self.worker_thread = threading.Thread(
+            target=self._worker,
+            daemon=True,
+        )
+        self.worker_thread.start()
+        self._debug(
+            "DECtalk USB device opened: 0dd0:2001",
+            debug.DebugLevel.INFO,
+            on_any_level=True,
+        )
+
+    def shutdown(self):
+        if not self._is_initialized:
+            return
+        self._stop_worker = True
+        self.clear_buffer()
+        self.text_queue.put(None)
+        if self.worker_thread:
+            self.worker_thread.join(timeout=0.5)
+
+        try:
+            with self.lock, self.immediate_lock:
+                usb_device = self.usb_device
+                self.usb_device = None
+                if usb_device is None:
+                    return
+                try:
+                    self.usb_util.release_interface(
+                        usb_device,
+                        self.interface,
+                    )
+                except (self.usb_core.USBError, OSError) as error:
+                    self._debug(
+                        f"DECtalk USB interface release failed: {error}",
+                        debug.DebugLevel.WARNING,
+                    )
+                self._dispose_usb_device(usb_device)
+        finally:
+            self._is_initialized = False
+
+    def cancel(self):
+        if not self._is_initialized:
+            return
+        self.clear_buffer()
+        self._write_endpoint(
+            self.immediate_endpoint,
+            b"\x06",
+            "cancel",
+            write_lock=self.immediate_lock,
+        )
+
+    def _write_bytes(self, data, description="data"):
+        self._write_endpoint(self.speech_endpoint, data, description)
+
+    def _write_endpoint(
+        self,
+        endpoint,
+        data,
+        description,
+        write_lock=None,
+    ):
+        if not data:
+            return
+        if write_lock is None:
+            write_lock = self.lock
+        with write_lock:
+            if self.usb_device is None:
+                return
+            try:
+                total_written = 0
+                while total_written < len(data):
+                    chunk = data[
+                        total_written : total_written + self.packet_size
+                    ]
+                    bytes_written = self.usb_device.write(
+                        endpoint,
+                        chunk,
+                        timeout=self.write_timeout,
+                    )
+                    if bytes_written != len(chunk):
+                        raise OSError(
+                            "USB write returned "
+                            f"{bytes_written} of {len(chunk)} bytes"
+                        )
+                    total_written += bytes_written
+                preview = self._format_bytes_preview(data)
+                self._debug(
+                    "DECtalk USB wrote "
+                    f"{total_written} {description} bytes "
+                    f"to endpoint 0x{endpoint:02x}: {preview}",
+                    debug.DebugLevel.INFO,
+                    on_any_level=True,
+                )
+            except (self.usb_core.USBError, OSError) as error:
+                self._debug(
+                    f"DECtalk USB write failed: {error}",
+                    debug.DebugLevel.ERROR,
+                    on_any_level=True,
+                )
+
+    def _dispose_usb_device(self, usb_device):
+        try:
+            self.usb_util.dispose_resources(usb_device)
+        except Exception as error:
+            self._debug(
+                f"DECtalk USB resource disposal failed: {error}",
+                debug.DebugLevel.WARNING,
+            )
+
+    def _load_usb_modules(self):
+        import usb.core
+        import usb.util
+
+        return usb.core, usb.util

tests/unit/test_dectalk_usb_driver.py

@@ -0,0 +1,273 @@
+import threading
+import time
+from unittest.mock import Mock
+
+import pytest
+
+from fenrirscreenreader.speechDriver import dectalkUsbDriver
+
+
+class FakeUsbDevice:
+    def __init__(self):
+        self.writes = []
+
+    def get_active_configuration(self):
+        return object()
+
+    def write(self, endpoint, data, timeout=None):
+        payload = bytes(data)
+        self.writes.append((endpoint, payload, timeout))
+        return len(payload)
+
+
+class FakeUsbCore:
+    USBError = OSError
+
+    class NoBackendError(ValueError):
+        pass
+
+    def __init__(self, device, find_error=None):
+        self.device = device
+        self.find_error = find_error
+        self.find_calls = []
+
+    def find(self, **kwargs):
+        self.find_calls.append(kwargs)
+        if self.find_error:
+            raise self.find_error
+        return self.device
+
+
+class FakeUsbUtil:
+    def __init__(
+        self,
+        claim_error=None,
+        release_error=None,
+        dispose_error=None,
+    ):
+        self.claim_error = claim_error
+        self.release_error = release_error
+        self.dispose_error = dispose_error
+        self.claimed = []
+        self.released = []
+        self.disposed = []
+
+    def claim_interface(self, device, interface):
+        if self.claim_error:
+            raise self.claim_error
+        self.claimed.append((device, interface))
+
+    def release_interface(self, device, interface):
+        if self.release_error:
+            raise self.release_error
+        self.released.append((device, interface))
+
+    def dispose_resources(self, device):
+        if self.dispose_error:
+            raise self.dispose_error
+        self.disposed.append(device)
+
+
+class BlockingUsbDevice(FakeUsbDevice):
+    def __init__(self):
+        super().__init__()
+        self.normal_write_started = threading.Event()
+        self.release_normal_write = threading.Event()
+        self.immediate_write_finished = threading.Event()
+
+    def write(self, endpoint, data, timeout=None):
+        if endpoint == 0x02:
+            self.normal_write_started.set()
+            self.release_normal_write.wait(timeout=1.0)
+        result = super().write(endpoint, data, timeout=timeout)
+        if endpoint == 0x04:
+            self.immediate_write_finished.set()
+        return result
+
+
+def build_environment():
+    return {
+        "runtime": {
+            "SettingsManager": Mock(),
+            "DebugManager": Mock(),
+        }
+    }
+
+
+def initialized_driver(monkeypatch):
+    device = FakeUsbDevice()
+    usb_core = FakeUsbCore(device)
+    usb_util = FakeUsbUtil()
+    speech_driver = dectalkUsbDriver.driver()
+    monkeypatch.setattr(
+        speech_driver,
+        "_load_usb_modules",
+        lambda: (usb_core, usb_util),
+    )
+    speech_driver.initialize(build_environment())
+    return speech_driver, device, usb_core, usb_util
+
+
+def wait_for_writes(device, count, timeout=1.0):
+    deadline = time.monotonic() + timeout
+    while len(device.writes) < count and time.monotonic() < deadline:
+        time.sleep(0.01)
+
+
+def test_dectalk_usb_driver_finds_and_claims_native_device(monkeypatch):
+    speech_driver, device, usb_core, usb_util = initialized_driver(monkeypatch)
+    try:
+        assert usb_core.find_calls == [
+            {"idVendor": 0x0DD0, "idProduct": 0x2001}
+        ]
+        assert usb_util.claimed == [(device, 0)]
+        assert speech_driver._is_initialized
+    finally:
+        speech_driver.shutdown()
+
+    assert usb_util.released == [(device, 0)]
+    assert usb_util.disposed == [device]
+
+
+def test_dectalk_usb_driver_writes_commands_and_speech(monkeypatch):
+    speech_driver, device, _, _ = initialized_driver(monkeypatch)
+    try:
+        speech_driver.set_rate(1.0)
+        speech_driver.set_pitch(1.0)
+        speech_driver.set_volume(0.5)
+        speech_driver.speak("Hello\nworld")
+        wait_for_writes(device, 4)
+
+        assert device.writes == [
+            (0x02, b"[:ra 650]", 1000),
+            (0x02, b"[:dv ap 350]", 1000),
+            (0x02, b"[:vo 50]", 1000),
+            (0x02, b"Hello world\x0b", 1000),
+        ]
+    finally:
+        speech_driver.shutdown()
+
+
+def test_dectalk_usb_driver_chunks_normal_writes(monkeypatch):
+    speech_driver, device, _, _ = initialized_driver(monkeypatch)
+    try:
+        speech_driver._write_bytes(b"x" * 70, "speech")
+        assert device.writes == [
+            (0x02, b"x" * 64, 1000),
+            (0x02, b"x" * 6, 1000),
+        ]
+    finally:
+        speech_driver.shutdown()
+
+
+def test_dectalk_usb_driver_uses_immediate_cancel_endpoint(monkeypatch):
+    speech_driver, device, _, _ = initialized_driver(monkeypatch)
+    try:
+        speech_driver.cancel()
+        assert device.writes == [(0x04, b"\x06", 1000)]
+    finally:
+        speech_driver.shutdown()
+
+
+def test_dectalk_usb_cancel_bypasses_blocked_normal_write(monkeypatch):
+    device = BlockingUsbDevice()
+    usb_core = FakeUsbCore(device)
+    usb_util = FakeUsbUtil()
+    speech_driver = dectalkUsbDriver.driver()
+    monkeypatch.setattr(
+        speech_driver,
+        "_load_usb_modules",
+        lambda: (usb_core, usb_util),
+    )
+    speech_driver.initialize(build_environment())
+    normal_thread = threading.Thread(
+        target=speech_driver._write_bytes,
+        args=(b"normal speech", "speech"),
+    )
+    cancel_thread = threading.Thread(target=speech_driver.cancel)
+    try:
+        normal_thread.start()
+        assert device.normal_write_started.wait(timeout=0.2)
+        cancel_thread.start()
+        assert device.immediate_write_finished.wait(timeout=0.2)
+    finally:
+        device.release_normal_write.set()
+        normal_thread.join(timeout=1.0)
+        cancel_thread.join(timeout=1.0)
+        speech_driver.shutdown()
+
+
+def test_dectalk_usb_driver_reports_missing_pyusb(monkeypatch):
+    speech_driver = dectalkUsbDriver.driver()
+
+    def missing_pyusb():
+        raise ImportError("No module named usb")
+
+    monkeypatch.setattr(speech_driver, "_load_usb_modules", missing_pyusb)
+
+    with pytest.raises(RuntimeError, match="PyUSB"):
+        speech_driver.initialize(build_environment())
+
+
+def test_dectalk_usb_driver_reports_missing_libusb_backend(monkeypatch):
+    speech_driver = dectalkUsbDriver.driver()
+    backend_error = FakeUsbCore.NoBackendError("No backend available")
+    usb_core = FakeUsbCore(None, find_error=backend_error)
+    monkeypatch.setattr(
+        speech_driver,
+        "_load_usb_modules",
+        lambda: (usb_core, FakeUsbUtil()),
+    )
+
+    with pytest.raises(RuntimeError, match="discovery failed.*backend"):
+        speech_driver.initialize(build_environment())
+
+
+def test_dectalk_usb_driver_reports_missing_device(monkeypatch):
+    speech_driver = dectalkUsbDriver.driver()
+    usb_core = FakeUsbCore(None)
+    usb_util = FakeUsbUtil()
+    monkeypatch.setattr(
+        speech_driver,
+        "_load_usb_modules",
+        lambda: (usb_core, usb_util),
+    )
+
+    with pytest.raises(RuntimeError, match="0dd0:2001"):
+        speech_driver.initialize(build_environment())
+
+
+def test_dectalk_usb_driver_reports_interface_permission_error(monkeypatch):
+    speech_driver = dectalkUsbDriver.driver()
+    device = FakeUsbDevice()
+    usb_core = FakeUsbCore(device)
+    usb_util = FakeUsbUtil(claim_error=PermissionError("access denied"))
+    monkeypatch.setattr(
+        speech_driver,
+        "_load_usb_modules",
+        lambda: (usb_core, usb_util),
+    )
+
+    with pytest.raises(RuntimeError, match="open failed.*access denied"):
+        speech_driver.initialize(build_environment())
+
+
+def test_dectalk_usb_shutdown_survives_cleanup_errors(monkeypatch):
+    device = FakeUsbDevice()
+    usb_core = FakeUsbCore(device)
+    usb_util = FakeUsbUtil(
+        release_error=OSError("release failed"),
+        dispose_error=OSError("dispose failed"),
+    )
+    speech_driver = dectalkUsbDriver.driver()
+    monkeypatch.setattr(
+        speech_driver,
+        "_load_usb_modules",
+        lambda: (usb_core, usb_util),
+    )
+    speech_driver.initialize(build_environment())
+
+    speech_driver.shutdown()
+
+    assert not speech_driver._is_initialized
+    assert speech_driver.usb_device is None

tests/unit/test_settings_validation.py

@@ -74,6 +74,9 @@ class TestSpeechSettingsValidation:
         self.manager._validate_setting_value("speech", "driver", "speechdDriver")
         self.manager._validate_setting_value("speech", "driver", "genericDriver")
         self.manager._validate_setting_value("speech", "driver", "dectalkDriver")
+        self.manager._validate_setting_value(
+            "speech", "driver", "dectalkUsbDriver"
+        )
         self.manager._validate_setting_value("speech", "driver", "doubletalkDriver")
         self.manager._validate_setting_value("speech", "driver", "litetalkDriver")
         self.manager._validate_setting_value("speech", "driver", "tripletalkDriver")