[Docs] Added USB documentation (espressif#6036)

Summary

Added USB documentation.

Closes: espressif#5784

Author: pedrominatel

docs/source/api/usb.rst

@@ -0,0 +1,331 @@
+#######
+USB API
+#######
+
+.. note:: This feature is only supported on ESP chips that have USB peripheral, like the ESP32-S2 and ESP32-S3. Some chips, like the ESP32-C3 include native CDC+JTAG peripheral that is not covered here.
+
+About
+-----
+
+The **Universal Serial Bus** is a widely used peripheral to exchange data between devices. USB was introduced on the ESP32, supporting both device and host mode.
+
+To learn about the USB, see the `USB.org`_ for developers.
+
+USB as Device
+*************
+
+In the device mode, the ESP32 acts as an USB device, like a mouse or keyboard to be connected to a host device, like your computer or smartphone.
+
+USB as Host
+***********
+
+The USB host mode, you can connect devices on the ESP32, like external modems, mouse and keyboards.
+
+.. note:: This mode is still under development for the ESP32.
+
+API Description
+---------------
+
+This is the common USB API description.
+
+For more supported USB classes implementation, see the following sections:
+
+.. toctree::
+   :maxdepth: 1
+   :caption: Classes:
+
+   USB CDC <usb_cdc>
+   USB MSC <usb_msc>
+
+USB Common
+**********
+
+These are the common APIs for the USB driver.
+
+onEvent
+^^^^^^^
+
+Event handling function to set the callback.
+
+.. code-block:: arduino
+
+    void onEvent(esp_event_handler_t callback);
+
+Event handling function for the specific event.
+
+.. code-block:: arduino
+
+    void onEvent(arduino_usb_event_t event, esp_event_handler_t callback);
+
+Where ``event`` can be:
+
+* ARDUINO_USB_ANY_EVENT
+* ARDUINO_USB_STARTED_EVENT
+* ARDUINO_USB_STOPPED_EVENT
+* ARDUINO_USB_SUSPEND_EVENT
+* ARDUINO_USB_RESUME_EVENT
+* ARDUINO_USB_MAX_EVENT
+
+VID
+^^^
+
+Set the Vendor ID. This 16 bits identification is used to identify the company that develops the product.
+
+.. note:: You can't define your own VID. If you need your own VID, you need to buy one. See https://www.usb.org/getting-vendor-id for more details.
+
+.. code-block:: arduino
+
+    bool VID(uint16_t v);
+
+
+Get the Vendor ID.
+
+.. code-block:: arduino
+
+    uint16_t VID(void);
+
+Returns the Vendor ID. The default value for the VID is: ``0x303A``.
+
+PID
+^^^
+
+Set the Product ID. This 16 bits identification is used to identify the product.
+
+.. code-block:: arduino
+
+    bool PID(uint16_t p);
+
+Get the Product ID.
+
+.. code-block:: arduino
+
+    uint16_t PID(void);
+
+Returns the Product ID. The default PID is: ``0x0002``.
+
+firmwareVersion
+^^^^^^^^^^^^^^^
+
+Set the firmware version. This is a 16 bits unsigned value.
+
+.. code-block:: arduino
+    
+    bool firmwareVersion(uint16_t version);
+
+Get the firmware version.
+
+.. code-block:: arduino
+
+    uint16_t firmwareVersion(void);
+
+Return the 16 bits unsigned value. The default value is: ``0x100``.
+
+usbVersion
+^^^^^^^^^^
+
+Set the USB version.
+
+.. code-block:: arduino
+
+    bool usbVersion(uint16_t version);
+
+Get the USB version.
+
+.. code-block:: arduino
+
+    uint16_t usbVersion(void);
+
+Return the USB version. The default value is: ``0x200`` (USB 2.0).
+
+usbPower
+^^^^^^^^
+
+Set the USB power as mA (current).
+
+.. note:: This configuration does not change the physical power output. This is only used for the USB device information.
+
+.. code-block:: arduino
+
+    bool usbPower(uint16_t mA);
+
+Get the USB power configuration.
+
+.. code-block:: arduino
+
+    uint16_t usbPower(void);
+
+Return the current in mA. The default value is: ``0x500`` (500mA).
+
+usbClass
+^^^^^^^^
+
+Set the USB class.
+
+.. code-block:: arduino
+
+    bool usbClass(uint8_t _class);
+
+Get the USB class.
+
+.. code-block:: arduino
+
+    uint8_t usbClass(void);
+
+Return the USB class. The default value is: ``TUSB_CLASS_MISC``.
+
+usbSubClass
+^^^^^^^^^^^
+
+Set the USB sub-class.
+
+.. code-block:: arduino
+
+    bool usbSubClass(uint8_t subClass);
+
+Get the USB sub-class.
+
+.. code-block:: arduino
+
+    uint8_t usbSubClass(void);
+
+Return the USB sub-class. The default value is: ``MISC_SUBCLASS_COMMON``.
+
+usbProtocol
+^^^^^^^^^^^
+
+Define the USB protocol.
+
+.. code-block:: arduino
+
+    bool usbProtocol(uint8_t protocol);
+
+Get the USB protocol.
+
+.. code-block:: arduino
+
+    uint8_t usbProtocol(void);
+
+Return the USB protocol. The default value is: ``MISC_PROTOCOL_IAD``
+
+usbAttributes
+^^^^^^^^^^^^^
+
+Set the USB attributes.
+
+.. code-block:: arduino
+
+    bool usbAttributes(uint8_t attr);
+
+Get the USB attributes.
+
+.. code-block:: arduino
+    
+    uint8_t usbAttributes(void);
+
+Return the USB attributes. The default value is: ``TUSB_DESC_CONFIG_ATT_SELF_POWERED``
+
+webUSB
+^^^^^^
+
+This function is used to enable the ``webUSB`` functionality.
+
+.. code-block:: arduino
+
+    bool webUSB(bool enabled);
+
+This function is used to get the ``webUSB`` setting.
+
+.. code-block:: arduino
+    
+    bool webUSB(void);
+
+Return the ``webUSB`` setting (`Enabled` or `Disabled`)
+
+productName
+^^^^^^^^^^^
+
+This function is used to define the product name.
+
+.. code-block:: arduino
+
+    bool productName(const char * name);
+
+This function is used to get the product's name.
+
+.. code-block:: arduino
+
+    const char * productName(void);
+
+manufacturerName
+^^^^^^^^^^^^^^^^
+
+This function is used to define the manufacturer name.
+
+.. code-block:: arduino
+
+    bool manufacturerName(const char * name);
+
+This function is used to get the manufacturer's name.
+
+.. code-block:: arduino
+    
+    const char * manufacturerName(void);
+
+serialNumber
+^^^^^^^^^^^^
+
+This function is used to define the serial number.
+
+.. code-block:: arduino
+
+    bool serialNumber(const char * name);
+
+This function is used to get the serial number.
+
+.. code-block:: arduino
+
+    const char * serialNumber(void);
+
+The default serial number is: ``0``.
+
+webUSBURL
+^^^^^^^^^
+
+This function is used to define the ``webUSBURL``.
+
+.. code-block:: arduino
+
+    bool webUSBURL(const char * name);
+
+This function is used to get the ``webUSBURL``.
+
+.. code-block:: arduino
+
+    const char * webUSBURL(void);
+
+The default ``webUSBURL`` is: https://espressif.github.io/arduino-esp32/webusb.html
+
+enableDFU
+^^^^^^^^^
+
+This function is used to enable the DFU capability.
+
+.. code-block:: arduino
+
+    bool enableDFU();
+
+begin
+^^^^^
+
+This function is used to start the peripheral using the default configuration.
+
+.. code-block:: arduino
+
+    bool begin();
+
+Example Code
+------------
+
+There are a collection of USB device examples on the project GitHub, including Firmware MSC update, USB CDC, HID and composite device.
+
+.. _USB.org: https://www.usb.org/developers