The driver allows users to use {IDF_TARGET_NAME} chips to develop USB devices on a top of the TinyUSB stack. TinyUSB is integrated with ESP-IDF to provide USB features of the framework. Using this driver the chip works as a composite device supporting several USB devices simultaneously. Currently, only the Communications Device Class (CDC) type of the device with the Abstract Control Model (ACM) subclass and the Musical Instrument Digital Interface (MIDI) are supported.
Our USB-OTG implementation is limited to {IDF_TARGET_USB_EP_NUM} USB endpoints ({IDF_TARGET_USB_EP_NUM_INOUT} IN/OUT endpoints and {IDF_TARGET_USB_EP_NUM_IN} IN endpoint) - find more information in `technical reference manual <{IDF_TARGET_TRM_EN_URL}>`_.
- Several of descriptor's parameters (see: Descriptors Configuration bellow)
- USB Serial low-level Configuration
- The verbosity of the TinyUSB's log
- Disable the TinyUSB main task (for the custom implementation)
Descriptors Configuration
^^^^^^^^^^^^^^^^^^^^^^^^^
The driver's descriptors are provided by the :cpp:type:`tinyusb_config_t` structure's :cpp:member:`descriptor` and :cpp:member:`string_descriptor` members. Therefore, users should initialize :cpp:type:`tinyusb_config_t` to their desired descriptor before calling :cpp:func:`tinyusb_driver_install` to install driver.
However, the driver also provides a default descriptor. The driver can be installed with the default descriptor by setting the :cpp:member:`descriptor` and :cpp:member:`string_descriptor` members of :cpp:type:`tinyusb_config_t` to `NULL` before calling :cpp:func:`tinyusb_driver_install`. The driver's default descriptor is specified using Menuconfig, where the following fields should be configured:
To initialize the driver, users should call :cpp:func:`tinyusb_driver_install`. The driver's configuration is specified in a :cpp:type:`tinyusb_config_t` structure that is passed as an argument to :cpp:func:`tinyusb_driver_install`.
Note that the :cpp:type:`tinyusb_config_t` structure can be zero initialized (e.g. ``tinyusb_config_t tusb_cfg = { 0 }``) or partially (as shown below). For any member that is initialized to `0` or `NULL`, the driver will use its default configuration values for that member (see example below)
USB specification mandates self-powered devices to monitor voltage level on USB's VBUS signal. As opposed to bus-powered devices, a self-powered device can be fully functional even without USB connection. The self-powered device detects connection and disconnection events by monitoring the VBUS voltage level. VBUS is considered valid if it rises above 4.75V and invalid if it falls below 4.35V.
No {IDF_TARGET_NAME} pin is 5V tolerant, so you must connect the VBUS to {IDF_TARGET_NAME} via a comparator with voltage thresholds as described above, or use a simple resistor voltage divider that will output (0.75 x Vdd) if VBUS is 4.4V (see figure below). In both cases, voltage on the sensing pin must be logic low within 3ms after the device is unplugged from USB host.
To use this feature, in :cpp:type:`tinyusb_config_t` you must set :cpp:member:`self_powered` to ``true`` and :cpp:member:`vbus_monitor_io` to GPIO number that will be used for VBUS monitoring.
If the CDC option is enabled in Menuconfig, the USB Serial Device could be initialized with :cpp:func:`tusb_cdc_acm_init` according to the settings from :cpp:type:`tinyusb_config_cdcacm_t` (see example below).
To specify callbacks you can either set the pointer to your :cpp:type:`tusb_cdcacm_callback_t` function in the configuration structure or call :cpp:func:`tinyusb_cdcacm_register_callback` after initialization.
The driver allows to redirect all standard application streams (stdinm stdout, stderr) to the USB Serial Device and return them to UART using :cpp:func:`esp_tusb_init_console`/:cpp:func:`esp_tusb_deinit_console` functions.
