lora-irrigation/rs485hid/usb_hid.py

import codecs
import struct

from usb_protocol.types import USBTransferType
from usb_protocol.emitters.descriptors import DeviceDescriptorCollection, get_string_descriptor


# Imported defines from usbd_def.h
USBD_IDX_LANGID_STR	= 0x00
USBD_IDX_MFC_STR	= 0x01
USBD_IDX_PRODUCT_STR	= 0x02
USBD_IDX_SERIAL_STR	= 0x03
USBD_IDX_CONFIG_STR	= 0x04
USBD_IDX_INTERFACE_STR	= 0x05

USB_CLASS_HID = 0x03
USB_CLASS_HID_NO_BOOT = 0x00
USB_CLASS_HID_BOOT = 0x01
USB_PROTOCOL_HID_NONE = 0x00
USB_PROTOCOL_HID_KEYBOARD = 0x01
USB_PROTOCOL_HID_MOUSE = 0x02

collection = DeviceDescriptorCollection()

with collection.DeviceDescriptor() as d:
	# https://pid.codes/1209/
	d.idVendor = 0x1209
	d.idProduct = 0x001
	d.bNumConfigurations = 1

	# Hack for ST reference code
	d.iProduct = USBD_IDX_PRODUCT_STR
	collection.add_descriptor(get_string_descriptor('RS-485 to HID'), d.iProduct)

with collection.ConfigurationDescriptor() as c:
	with c.InterfaceDescriptor() as i:
		i.bInterfaceNumber = 0
		i.bInterfaceClass = USB_CLASS_HID
		i.bInterfaceSubclass = USB_CLASS_HID_BOOT
		i.bInterfaceProtocol = USB_PROTOCOL_HID_KEYBOARD

		report_desc = codecs.decode('05010906a101050719e029e71500250175019508810295017508810195057501050819012905910295017503910195067508150025650507190029658100c0', 'hex')
		collection.add_descriptor(report_desc, descriptor_type=0x22)

		hid_desc = codecs.decode('09211101000122', 'hex') + struct.pack('<H', len(report_desc))

		# add HID Descriptor after interface, but before
		# endpoint descriptors per HID v1.11 § 7.1
		i.add_subordinate_descriptor(hid_desc)

		# No OUT endpoint.  Use the SET_REPORT via the control EP

		with i.EndpointDescriptor() as e:
			e.bEndpointAddress = 0x81

			e.bmAttributes = USBTransferType.INTERRUPT

			# it'd be good to adjust based upon FS vs LS
			e.bInterval = 10	# polling interval (LS/FS in ms)

			# Full-speed max size
			e.wMaxPacketSize = 64