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144 lines
5.5 KiB
ReStructuredText
144 lines
5.5 KiB
ReStructuredText
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USB Driver
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==========
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Overview
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--------
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The driver allows users to use {IDF_TARGET_NAME} chips to develop USB devices on top the TinyUSB stack. TinyUSB is integrating with ESP-IDF to provide USB features of the framework. Using this driver the chip works as a composite device supporting to represent several USB devices simultaneously. Currently, only the communications device class (CDC) type of the device with the ACM (Abstract Control Model) subclass is supported.
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Features
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--------
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- Configuration of device and string USB descriptors
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- USB Serial Device (CDC-ACM)
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- Input and output through USB Serial Device
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Hardware USB Connection
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-----------------------
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- Any board with the {IDF_TARGET_NAME} chip with USB connectors or with exposed USB's D+ and D- (DATA+/DATA-) pins.
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If the board has no USB connector but has the pins, connect pins directly to the host (e.g. with do-it-yourself cable from any USB connection cable). For example, connect GPIO19/20 to D-/D+ respectively for an ESP32-S2 board:
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.. figure:: ../../../_static/usb-board-connection.png
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:align: center
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:alt: Connection of a board to a host ESP32-S2
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:figclass: align-center
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Driver Structure
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----------------
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As the basis is used the TinyUSB stack.
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On top of it the driver implements:
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- Customization of USB descriptors
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- Serial device support
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- Redirecting of standard streams through the Serial device
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- Encapsulated driver's task servicing the TinyuSB
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Configuration
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-------------
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Via Menuconfig options you can specify:
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- Several of descriptor's parameters (see: Descriptors Configuration bellow)
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- USB Serial low-level Configuration
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- The verbosity of the TinyUSB's log
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- Disable the TinyUSB main task (for the custom implementation)
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Descriptors Configuration
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^^^^^^^^^^^^^^^^^^^^^^^^^
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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.
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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:
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- PID
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- VID
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- bcdDevice
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- Manufacturer
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- Product name
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- Name of CDC device if it is On
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- Serial number
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If you want to use own descriptors with extended modification, you can define them during the driver installation process
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Install Driver
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--------------
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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`.
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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)
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.. code-block:: c
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tinyusb_config_t partial_init = {
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.descriptor = NULL; //Uses default descriptor specified in Menuconfig
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.string_descriptor = NULL; //Uses default string specified in Menuconfig
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.external_phy = false;
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}
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USB Serial Device (CDC-ACM)
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---------------------------
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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).
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.. code-block:: c
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tinyusb_config_cdcacm_t amc_cfg = {
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.usb_dev = TINYUSB_USBDEV_0,
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.cdc_port = TINYUSB_CDC_ACM_0,
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.rx_unread_buf_sz = 64,
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.callback_rx = NULL,
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.callback_rx_wanted_char = NULL,
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.callback_line_state_changed = NULL,
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.callback_line_coding_changed = NULL
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};
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tusb_cdc_acm_init(&amc_cfg);
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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.
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USB Serial Console
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^^^^^^^^^^^^^^^^^^
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The driver allows to redirect all standard application strings (stdin/out/err) to the USB Serial Device and return them to UART using :cpp:func:`esp_tusb_init_console`/:cpp:func:`esp_tusb_deinit_console` functions.
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Application Examples
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--------------------
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The table below describes the code examples available in the directory :example:`peripherals/usb/`.
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.. list-table::
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:widths: 35 65
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:header-rows: 1
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* - Code Example
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- Description
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* - :example:`peripherals/usb/tusb_console`
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- How to set up {IDF_TARGET_NAME} chip to get log output via Serial Device connection
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* - :example:`peripherals/usb/tusb_sample_descriptor`
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- How to set up {IDF_TARGET_NAME} chip to work as a Generic USB Device with a user-defined descriptor
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* - :example:`peripherals/usb/tusb_serial_device`
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- How to set up {IDF_TARGET_NAME} chip to work as a USB Serial Device
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API Reference
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-------------
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.. include-build-file:: inc/tinyusb.inc
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.. include-build-file:: inc/tinyusb_types.inc
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.. include-build-file:: inc/tusb_cdc_acm.inc
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.. include-build-file:: inc/tusb_console.inc
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.. include-build-file:: inc/tusb_tasks.inc
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.. include-build-file:: inc/vfs_tinyusb.inc
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