Enable usb_hid device for Raspberry Pi PICO 2

[czhang-seegrid]

Hi,
I am struggling with building a uf2 file that support usb_hid devices for Raspberry Pi PICO 2 (RP2350). I'd like to find instructions for building the image Can someone help?
Thank you!

[GitHubsSilverBullet]

Hi, I am struggling with building a uf2 file that support usb_hid devices for Raspberry Pi PICO 2 (RP2350).
Any particular reason for not using ›machine.USBDevice‹ directly?

[czhang-seegrid]

No. I just don't know it. I assume it can send and receive reports? Where can I find example codes for using machine.USBDevice. I am a rookie for USB stuff. Thank you!

[GitHubsSilverBullet]

MicroPython-latest/library/machine.USBDevice.html
has all the info.

[czhang-seegrid]

Thank you very much!

[czhang-seegrid]

@GitHubsSilverBullet I got this sample code using USBDevice class as a hid as main.py. It doesn't enumerate correctly when connecting to an Ubuntu machine. It always shows as default PICO 2 device but the REPL is not reponsive. I wonder if you can help.
I am using MicroPython 1.25 and Raspberry Pi PICO 2.

Thank you!

# main.py 
import machine
import time
import os


HID_REPORT_DESCRIPTOR = bytes([
    0x06, 0x00, 0xFF,  # Usage Page (Vendor-Defined 1)
    0x09, 0x01,        # Usage (Vendor-Defined 1)
    0xA1, 0x01,        # Collection (Application)
    
    # --- Input Report ---
    0x85, 0x01,        #   Report ID (1)
    0x09, 0x02,        #   Usage (Vendor-Defined 2)
    0x15, 0x00,        #   Logical Minimum (0)
    0x26, 0xFF, 0x00,  #   Logical Maximum (255)
    0x75, 0x08,        #   Report Size (8 bits)
    0x95, 0x08,        #   Report Count (8 bytes)
    0x81, 0x02,        #   Input (Data, Var, Abs)
    
    # --- Output Report ---
    0x85, 0x02,        #   Report ID (2)
    0x09, 0x03,        #   Usage (Vendor-Defined 3)
    0x15, 0x00,        #   Logical Minimum (0)
    0x26, 0xFF, 0x00,  #   Logical Maximum (255)
    0x75, 0x08,        #   Report Size (8 bits)
    0x95, 0x08,        #   Report Count (8 bytes)
    0x91, 0x02,        #   Output (Data, Var, Abs)
    
    0xC0,              # End Collection
])


DEVICE_DESCRIPTOR = bytes([
    0x12,  # bLength: 18 bytes
    0x01,  # bDescriptorType: DEVICE
    0x00, 0x02,  # bcdUSB: USB 2.0
    0x00,  # bDeviceClass: (defined in interface)
    0x00,  # bDeviceSubClass
    0x00,  # bDeviceProtocol
    0x40,  # bMaxPacketSize0: 64 bytes
    0xAD, 0xDE,  # idVendor: 0xDEAD (a common test VID)
    0xEF, 0xBE,  # idProduct: 0xBEEF (a common test PID)
    0x00, 0x01,  # bcdDevice: 1.00
    0x01,  # iManufacturer
    0x02,  # iProduct
    0x03,  # iSerialNumber
    0x01,  # bNumConfigurations
])


CONFIG_DESCRIPTOR = bytes([
    # Configuration
    0x09,  # bLength
    0x02,  # bDescriptorType: CONFIGURATION
    0x29, 0x00,  # wTotalLength: 41 bytes (9+9+9+7+7)
    0x01,  # bNumInterfaces
    0x01,  # bConfigurationValue
    0x00,  # iConfiguration
    0x80,  # bmAttributes: bus powered
    0xFA,  # bMaxPower: 500 mA

    # Interface
    0x09,  # bLength
    0x04,  # bDescriptorType: INTERFACE
    0x00,  # bInterfaceNumber
    0x00,  # bAlternateSetting
    0x02,  # bNumEndpoints (1 IN, 1 OUT)
    0x03,  # bInterfaceClass: HID
    0x00,  # bInterfaceSubClass
    0x00,  # bInterfaceProtocol
    0x00,  # iInterface

    # HID
    0x09,  # bLength
    0x21,  # bDescriptorType: HID
    0x11, 0x01,  # bcdHID: 1.11
    0x00,  # bCountryCode
    0x01,  # bNumDescriptors
    0x22,  # bDescriptorType: REPORT
    len(HID_REPORT_DESCRIPTOR), 0x00,  # wDescriptorLength

    # Endpoint IN
    0x07,  # bLength
    0x05,  # bDescriptorType: ENDPOINT
    0x81,  # bEndpointAddress: IN Endpoint 1
    0x03,  # bmAttributes: Interrupt
    0x40, 0x00,  # wMaxPacketSize: 64 bytes
    0x0A,  # bInterval: 10 ms polling interval

    # Endpoint OUT
    0x07,  # bLength
    0x05,  # bDescriptorType: ENDPOINT
    0x01,  # bEndpointAddress: OUT Endpoint 1
    0x03,  # bmAttributes: Interrupt
    0x40, 0x00,  # wMaxPacketSize: 64 bytes
    0x0A,  # bInterval: 10 ms polling interval
])


STRING_DESCRIPTORS = [
    # 0: Language
    b'\x04\x03\x09\x04',  # LangID: 0x0409 (English US)
    # 1: Manufacturer
    "MicroPython".encode('utf-16le'),
    # 2: Product
    "Generic HID Device".encode('utf-16le'),
    # 3: Serial
    "123456".encode('utf-16le'),
]


usb_configured = False
transfer_in_progress = False

def hid_handler(event, data):
    global usb_configured, transfer_in_progress
    if event == "set_config":
        print("USB configured by host.")
        usb_configured = True
    elif event == "set_report":
        print(f"Received OUT report (packet size: {len(data)}): {bytes(data)}")
    elif event == "ep_in_complete":
        if data == 1: 
            transfer_in_progress = False

try:
    print("Initializing USBDevice...")
    usb_dev = machine.USBDevice(
        dev_descriptor=DEVICE_DESCRIPTOR,
        config_descriptor=CONFIG_DESCRIPTOR,
        string_descriptors=STRING_DESCRIPTORS,
        hid={0: (HID_REPORT_DESCRIPTOR, hid_handler, (1, 1), 64)},
    )
    # usb_dev.connect()  # <- does not exist
  
    print("USBDevice Initialized. Device should be re-enumerating now.")
    
except Exception as e:
    print("--- FATAL ERROR DURING INIT ---")
    import sys
    sys.print_exception(e)
    led = machine.Pin("LED", machine.Pin.OUT)
    while True:
        led.toggle(); time.sleep(0.1)

# --- Main Loop ---
led = machine.Pin("LED", machine.Pin.OUT)
counter = 0

report_buffer = bytearray(64)

while True:
    if usb_configured and not transfer_in_progress:
        try:
            report_buffer[:] = b'\x00' * 64
            report_buffer[0] = 0x01 # Report ID
            report_buffer[1] = counter & 0xFF
            
            transfer_in_progress = True
            usb_dev.submit_xfer(1, report_buffer) 
            
            counter = (counter + 1) & 0xFF
            led.toggle()
        except Exception as e:
            print(f"Error submitting transfer: {e}")
            transfer_in_progress = False
    time.sleep(.1)