custom_gamepad.py

# This is only one example of a gamepad descriptor, and may not suit your needs.
GAMEPAD_REPORT_DESCRIPTOR = bytes((
    0x05, 0x01,  # Usage Page (Generic Desktop Ctrls)
    0x09, 0x05,  # Usage (Game Pad)
    0xA1, 0x01,  # Collection (Application)
    0x85, 0x04,  #   Report ID (4)
    0x05, 0x09,  #   Usage Page (Button)
    0x19, 0x01,  #   Usage Minimum (Button 1)
    0x29, 0x20,  #   Usage Maximum (Button 32)
    0x15, 0x00,  #   Logical Minimum (0)
    0x25, 0x01,  #   Logical Maximum (1)
    0x75, 0x01,  #   Report Size (1)
    0x95, 0x20,  #   Report Count (32)
    0x81, 0x02,  #   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
    0x05, 0x01,  #   Usage Page (Generic Desktop Ctrls)
    0x15, 0x81,  #   Logical Minimum (-127)
    0x25, 0x7F,  #   Logical Maximum (127)
    0x09, 0x30,  #   Usage (X)
    0x09, 0x31,  #   Usage (Y)
    0x09, 0x32,  #   Usage (Z)
    0x09, 0x35,  #   Usage (Rz)
    0x75, 0x08,  #   Report Size (8)
    0x95, 0x04,  #   Report Count (4)
    0x81, 0x02,  #   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)

    ## hat switch 1 byte extra but only 5 bit used
    # https://stackoverflow.com/questions/60132199/cannot-figure-out-how-to-send-data-to-hat-switch-from-stm32f103c8-to-pc-via-usb
    0x05, 0x01,  # Usage Page: Generic Desktop
    0x09, 0x39,  # Usage: Hat Switch,
    0x15, 0x00,  # Logical Min: 0
    0x25, 0x07,  # Logical Max: 7
    0x46, 0x3B, 0x01, # Physical Maximum: 315 degrees (Optional)
    0x75, 0x08,  # ReportSize: 8
    0x95, 0x01,  # Report Count: 1
    0x65, 0x14,  # Unit: English Rotation / Angular Position 1 degree(Optional)
    0x81, 0x42,  # Input: Data, Var, Abs, Null State

    0xC0,        # End Collection
))


# Reuse this bytearray to send mouse reports.
# Typically controllers start numbering buttons at 1 rather than 0.
# report[0] buttons 1-8 (LSB is button 1)
# report[1] buttons 9-16
# report[2] buttons 17-24
# report[3] buttons 24-32
# report[4] joystick 0 x: -127 to 127
# report[5] joystick 0 y: -127 to 127
# report[6] joystick 1 x: -127 to 127
# report[7] joystick 1 y: -127 to 127
# report[8] joystick 1 hat/d-pad


struct.pack_into(
    "<IbbbbB", # < little endian, I 32-bit (4-byte) field for 32 buttons, b signed 8-bit integer, B unsigned 8-bit integer
    self._report,
    0,
    self._buttons_state,
    self._joy_x,
    self._joy_y,
    self._joy_z,
    self._joy_r_z,
    self._hat & 0b11111
)