Add basic keypad support

Author: turmoni

micropython/usbd/hidkeypad.py

@@ -0,0 +1,39 @@
+# Implement a keypad
+
+from .hid import HIDInterface
+from .keycodes import KEYPAD_KEYS_TO_KEYCODES
+from micropython import const
+_INTERFACE_PROTOCOL_KEYBOARD = const(0x01)
+
+# Basic 3-button mouse HID Report Descriptor.
+# This is cribbed from Appendix E.10 of the HID v1.11 document.
+_KEYPAD_REPORT_DESC = bytes(
+    [
+        0x05, 0x01,  # Usage Page (Generic Desktop)
+            0x09, 0x07,  # Usage (Keypad)
+            0xA1, 0x01,  # Collection (Application)
+                0x05, 0x07,  # Usage Page (Keypad)
+                0x19, 0x00,  # Usage Minimum (00),
+                0x29, 0xff,  # Usage Maximum (ff),
+                0x15, 0x00,  # Logical Minimum (0),
+                0x25, 0xff,  # Logical Maximum (ff),
+                0x95, 0x03,  # Report Count (3),
+                0x75, 0x08,  # Report Size (8),
+                0x81, 0x00,  # Input (Data, Array, Absolute)
+            0xC0,  # End Collection
+    ]
+)
+
+
+class KeypadInterface(HIDInterface):
+    # Very basic synchronous USB keypad HID interface
+
+    def __init__(self):
+        super().__init__(
+            _KEYPAD_REPORT_DESC,
+            protocol=_INTERFACE_PROTOCOL_KEYBOARD,
+            interface_str="MicroPython Keypad!",
+        )
+
+    def send_report(self, key):
+        super().send_report(KEYPAD_KEYS_TO_KEYCODES[key].to_bytes(1, "big"))

micropython/usbd/keycodes.py

@@ -0,0 +1,7 @@
+_KEYPAD_KEYS = [
+    "<NumLock>", "/", "*", "-", "+", "<Enter>", "1", "2", "3", "4", "5", "6",
+    "7", "8", "9", "0", "."
+]
+
+KEYPAD_KEYCODES_TO_KEYS = {k + 0x53: v for k, v in enumerate(_KEYPAD_KEYS)}
+KEYPAD_KEYS_TO_KEYCODES = {v: k for k, v in KEYPAD_KEYCODES_TO_KEYS.items()}