Merge pull request #7 from FoamyGuy/find_boot_keyboard

add find_boot_keyboard function and example

Author: tannewt

adafruit_usb_host_descriptors.py

@@ -14,6 +14,11 @@
 
 from micropython import const
 
+try:
+    from typing import Literal
+except ImportError:
+    pass
+
 __version__ = "0.0.0+auto.0"
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_USB_Host_Descriptors.git"
 
@@ -39,6 +44,7 @@
 INTERFACE_HID = 0x03
 SUBCLASS_BOOT = 0x01
 PROTOCOL_MOUSE = 0x02
+PROTOCOL_KEYBOARD = 0x01
 
 
 def get_descriptor(device, desc_type, index, buf, language_id=0):
@@ -77,13 +83,7 @@ def get_configuration_descriptor(device, index):
     return full_buf
 
 
-def find_boot_mouse_endpoint(device):
-    """
-    Try to find a boot mouse endpoint in the device and return its
-    interface index, and endpoint address.
-    :param device: The device to search within
-    :return: mouse_interface_index, mouse_endpoint_address if found, or None, None otherwise
-    """
+def _find_boot_endpoint(device, protocol_type: Literal[PROTOCOL_MOUSE, PROTOCOL_KEYBOARD]):
     config_descriptor = get_configuration_descriptor(device, 0)
     i = 0
     mouse_interface_index = None
@@ -99,7 +99,7 @@ def find_boot_mouse_endpoint(device):
             if (
                 interface_class == INTERFACE_HID
                 and interface_subclass == SUBCLASS_BOOT
-                and interface_protocol == PROTOCOL_MOUSE
+                and interface_protocol == protocol_type
             ):
                 found_mouse = True
                 mouse_interface_index = interface_number
@@ -111,3 +111,23 @@ def find_boot_mouse_endpoint(device):
                     return mouse_interface_index, endpoint_address
         i += descriptor_len
     return None, None
+
+
+def find_boot_mouse_endpoint(device):
+    """
+    Try to find a boot mouse endpoint in the device and return its
+    interface index, and endpoint address.
+    :param device: The device to search within
+    :return: mouse_interface_index, mouse_endpoint_address if found, or None, None otherwise
+    """
+    return _find_boot_endpoint(device, PROTOCOL_MOUSE)
+
+
+def find_boot_keyboard_endpoint(device):
+    """
+    Try to find a boot keyboard endpoint in the device and return its
+    interface index, and endpoint address.
+    :param device: The device to search within
+    :return: keyboard_interface_index, keyboard_endpoint_address if found, or None, None otherwise
+    """
+    return _find_boot_endpoint(device, PROTOCOL_KEYBOARD)

examples/usb_host_descriptors_find_boot_keyboard.py

@@ -0,0 +1,45 @@
+# SPDX-FileCopyrightText: Copyright (c) 2025 Tim Cocks for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+import array
+
+import usb
+
+import adafruit_usb_host_descriptors
+
+keyboard_interface_index = None
+keyboard_endpoint_address = None
+keyboard = None
+
+# scan for connected USB devices
+for device in usb.core.find(find_all=True):
+    # check for boot keyboard endpoints on this device
+    keyboard_interface_index, keyboard_endpoint_address = (
+        adafruit_usb_host_descriptors.find_boot_keyboard_endpoint(device)
+    )
+    # if a boot keyboard interface index and endpoint address were found
+    if keyboard_interface_index is not None and keyboard_endpoint_address is not None:
+        keyboard = device
+
+        # detach device from kernel if needed
+        if keyboard.is_kernel_driver_active(0):
+            keyboard.detach_kernel_driver(0)
+
+        # set the configuration so the keyboard can be used
+        keyboard.set_configuration()
+
+buf = array.array("b", [0] * 8)
+
+while True:
+    # try to read data from the keyboard
+    try:
+        count = keyboard.read(keyboard_endpoint_address, buf, timeout=10)
+
+    # if there is no data it will raise USBTimeoutError
+    except usb.core.USBTimeoutError:
+        # Nothing to do if there is no data for this keyboard
+        continue
+
+    for b in buf:
+        print(hex(b), end=" ")
+    print()