Platform-Specific Implementations

This section describes how XRUSB implements USB device and endpoint backends on different platforms, and what the common device-construction shape looks like.

It is recommended to derive the device serial number from the platform-provided Unique ID (UID).

Example:

/* USB Classes */
LibXR::USB::CDCUart cdc_uart;
LibXR::USB::HIDKeyboard hid_keyboard;

static constexpr auto LANG_PACK =
    LibXR::USB::DescriptorStrings::MakeLanguagePack(
        /* Language Code */
        LibXR::USB::DescriptorStrings::Language::EN_US, 
        /* Manufacturer */
        "XRobot",
        /* Product */
        "XRUSB USB CDC Demo", 
        /* Serial Number string prefix (human-readable) */
        "XRUSB-DEMO-");


XXXUSBDevice usb(
    /* USB Hardware and Endpoints config */
    ..., 
    /* EP0 Packet Size */
    USB::DeviceDescriptor::PacketSize0::SIZE_8,
    /* Vendor ID */
    0x1D50,
    /* Product ID */
    0x6199,
    /* BcdDevice */
    0x0100,
    /* Language Pack */
    LANG_PACK,
    /* Classes */
    {{&cdc_uart, &hid_keyboard}},
    /* Serial Number UID (hex byte array, optional) */
    {addr, size});

The VID / PID / bcdDevice values in the example are only showing the constructor shape. For real project values, check VID/PID and serial usage conventions first. If one device class must match a specific host ecosystem, the class-specific page takes priority.

What actually changes across platforms is:

the USB device object itself, for example STM32USBDevice... or CH32USBDevice...
endpoint-buffer declaration style
low-level resource organization such as FIFO / PMA / DMA

Upper-layer classes such as CDCUart and HIDKeyboard are generally wired in the same way: pass them through the final class list of the device constructor.

Additional notes:

for ESP32-S3, mainline provides a dedicated ESP32USBDevice device-side implementation;
for ESP32-C3 / ESP32-C6, current mainline more commonly uses ESP32CDCJtag as a USB Serial/JTAG UART backend, which is not part of the generic XRUSB device-controller path.

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