micropython-lib/micropython/usb/examples/device/hid_custom_keypad_example.py

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# MicroPython USB HID custom Keypad example
#
# This example demonstrates creating a custom HID device with its own
# HID descriptor, in this case for a USB number keypad.
#
# For higher level examples that require less code to use, see mouse_example.py
# and keyboard_example.py
#
# To run this example:
#
# 1. Make sure `usb-device-hid` is installed via: mpremote mip install usb-device-hid
#
# 2. Run the example via: mpremote run hid_custom_keypad_example.py
#
# 3. mpremote will exit with an error after the previous step, because when the
# example runs the existing USB device disconnects and then re-enumerates with
# the custom HID interface present. At this point, the example is running.
#
# 4. To see output from the example, re-connect: mpremote connect PORTNAME
#
# MIT license; Copyright (c) 2023 Dave Wickham, 2023-2024 Angus Gratton
from micropython import const
import time
import usb.device
from usb.device.hid import HIDInterface
_INTERFACE_PROTOCOL_KEYBOARD = const(0x01)
def keypad_example():
k = KeypadInterface()
usb.device.get().init(k, builtin_driver=True)
while not k.is_open():
time.sleep_ms(100)
while True:
time.sleep(2)
print("Press NumLock...")
k.send_key("<NumLock>")
time.sleep_ms(100)
k.send_key()
time.sleep(1)
# continue
print("Press ...")
for _ in range(3):
time.sleep(0.1)
k.send_key(".")
time.sleep(0.1)
k.send_key()
print("Starting again...")
class KeypadInterface(HIDInterface):
# Very basic synchronous USB keypad HID interface
def __init__(self):
super().__init__(
_KEYPAD_REPORT_DESC,
set_report_buf=bytearray(1),
protocol=_INTERFACE_PROTOCOL_KEYBOARD,
interface_str="MicroPython Keypad",
)
self.numlock = False
def on_set_report(self, report_data, _report_id, _report_type):
report = report_data[0]
b = bool(report & 1)
if b != self.numlock:
print("Numlock: ", b)
self.numlock = b
def send_key(self, key=None):
if key is None:
self.send_report(b"\x00")
else:
self.send_report(_key_to_id(key).to_bytes(1, "big"))
# See HID Usages and Descriptions 1.4, section 10 Keyboard/Keypad Page (0x07)
#
# This keypad example has a contiguous series of keys (KEYPAD_KEY_IDS) starting
# from the NumLock/Clear keypad key (0x53), but you can send any Key IDs from
# the table in the HID Usages specification.
_KEYPAD_KEY_OFFS = const(0x53)
_KEYPAD_KEY_IDS = [
"<NumLock>",
"/",
"*",
"-",
"+",
"<Enter>",
"1",
"2",
"3",
"4",
"5",
"6",
"7",
"8",
"9",
"0",
".",
]
def _key_to_id(key):
# This is a little slower than making a dict for lookup, but uses
# less memory and O(n) can be fast enough when n is small.
return _KEYPAD_KEY_IDS.index(key) + _KEYPAD_KEY_OFFS
# HID Report descriptor for a numeric keypad
#
# fmt: off
_KEYPAD_REPORT_DESC = (
b'\x05\x01' # Usage Page (Generic Desktop)
b'\x09\x07' # Usage (Keypad)
b'\xA1\x01' # Collection (Application)
b'\x05\x07' # Usage Page (Keypad)
b'\x19\x00' # Usage Minimum (0)
b'\x29\xFF' # Usage Maximum (ff)
b'\x15\x00' # Logical Minimum (0)
b'\x25\xFF' # Logical Maximum (ff)
b'\x95\x01' # Report Count (1),
b'\x75\x08' # Report Size (8),
b'\x81\x00' # Input (Data, Array, Absolute)
b'\x05\x08' # Usage page (LEDs)
b'\x19\x01' # Usage Minimum (1)
b'\x29\x01' # Usage Maximum (1),
b'\x95\x01' # Report Count (1),
b'\x75\x01' # Report Size (1),
b'\x91\x02' # Output (Data, Variable, Absolute)
b'\x95\x01' # Report Count (1),
b'\x75\x07' # Report Size (7),
b'\x91\x01' # Output (Constant) - padding bits
b'\xC0' # End Collection
)
# fmt: on
keypad_example()