adding some polish (#709)

* adding some polish

* updating based on reviewer Grazfather's kind suggestions

Author: aaronhmiller

examples/raspberrypi/rp2xxx/scripts/list_devices.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+import usb.core
+
+# Find ALL USB devices
+devices = usb.core.find(find_all=True)
+
+print("Connected USB devices:")
+print("-" * 60)
+for dev in devices:
+    print(f"Vendor ID:  0x{dev.idVendor:04x}")
+    print(f"Product ID: 0x{dev.idProduct:04x}")
+    try:
+        print(f"Manufacturer: {dev.manufacturer}")
+        print(f"Product: {dev.product}")
+    except usb.core.USBError as e:
+        print("(Could not read device strings: {e})")
+    except ValueError:
+        print("(Device has no string descriptors)")
+    print("-" * 60)

examples/raspberrypi/rp2xxx/scripts/usb_device_loopback.py

@@ -10,39 +10,98 @@
 
 import usb.core
 import usb.util
+import time
 
-# find our device
-dev = usb.core.find(idVendor=0x0000, idProduct=0x0001)
-
-# was it found?
-if dev is None:
-    raise ValueError('Device not found')
-
-# get an endpoint instance
-cfg = dev.get_active_configuration()
-intf = cfg[(0, 0)]
-
-outep = usb.util.find_descriptor(
-    intf,
-    # match the first OUT endpoint
-    custom_match= \
-        lambda e: \
-            usb.util.endpoint_direction(e.bEndpointAddress) == \
-            usb.util.ENDPOINT_OUT)
-
-inep = usb.util.find_descriptor(
-    intf,
-    # match the first IN endpoint
-    custom_match= \
-        lambda e: \
-            usb.util.endpoint_direction(e.bEndpointAddress) == \
-            usb.util.ENDPOINT_IN)
-
-assert inep is not None
-assert outep is not None
-
-test_string = "Hello World!"
-outep.write(test_string)
-from_device = inep.read(len(test_string))
-
-print("Device Says: {}".format(''.join([chr(x) for x in from_device])))
+try:
+    # find our device
+    # use list_devices.py for idVendor and idProduct values
+    dev = usb.core.find(idVendor=0x0000, idProduct=0x0001)
+
+    # was it found?
+    if dev is None:
+        raise ValueError("Device not found. Verify that device is attached, then check vendor and product settings.")
+
+    print("Device found!")
+
+    # Detach kernel driver BEFORE setting configuration
+    detached_interfaces = []
+    for interface in [0, 1]:
+        if dev.is_kernel_driver_active(interface):
+            try:
+                dev.detach_kernel_driver(interface)
+                detached_interfaces.append(interface)
+                print(f"Kernel driver detached from interface {interface}")
+            except:
+                pass
+
+    # Set configuration
+    try:
+        dev.set_configuration()
+        print("Configuration set")
+    except usb.core.USBError as e:
+        print(f"Configuration already set or error: {e}")
+
+    # get an endpoint instance
+    cfg = dev.get_active_configuration()
+    intf = cfg[(1, 0)]  # Interface 1, Alt 0
+
+    outep = usb.util.find_descriptor(
+        intf,
+        custom_match=lambda e: usb.util.endpoint_direction(e.bEndpointAddress) == usb.util.ENDPOINT_OUT)
+
+    inep = usb.util.find_descriptor(
+        intf,
+        custom_match=lambda e: usb.util.endpoint_direction(e.bEndpointAddress) == usb.util.ENDPOINT_IN)
+
+    if inep is None:
+        raise ValueError("IN endpoint not found")
+    if outep is None:
+        raise ValueError("OUT endpoint not found")
+
+    print(f"OUT endpoint: 0x{outep.bEndpointAddress:02x}")
+    print(f"IN endpoint: 0x{inep.bEndpointAddress:02x}")
+
+    # Clear any stale data from the IN endpoint
+    try:
+        while True:
+            inep.read(64, timeout=100)  # Short timeout to flush buffer
+    except usb.core.USBTimeoutError:
+        pass  # Good, buffer is empty now
+
+    test_string = "Hello World!"
+    print(f"\nSending: {test_string}")
+
+    bytes_written = outep.write(test_string, timeout=1000)
+    print(f"Wrote {bytes_written} bytes")
+    
+    time.sleep(0.1)  # Give device a moment to process
+    
+    from_device = inep.read(64, timeout=2000)
+    print(f"Received {len(from_device)} bytes")
+    print("Device Says: {}".format(''.join([chr(x) for x in from_device])))
+except usb.core.USBTimeoutError:
+    print("\nTimeout! The device isn't responding.")
+except usb.core.USBError as e:
+    print(f"USB Error: {e}")
+finally:
+    # Proper cleanup
+    print("\nCleaning up...")
+    try:
+        # Release interfaces
+        usb.util.release_interface(dev, 1)
+        usb.util.release_interface(dev, 0)
+        
+        # Reattach kernel driver if we detached it
+        for interface in detached_interfaces:
+            try:
+                dev.attach_kernel_driver(interface)
+                print(f"Kernel driver reattached to interface {interface}")
+            except:
+                print(f"Could not reattach kernel driver to interface {interface}")
+        
+        # Dispose of the device object
+        usb.util.dispose_resources(dev)
+    except:
+        print("Attempts to cleanup by releasing interfaces failed.")
+    
+    print("Done!")