# USB Host

[中文]

The document provides information regarding the USB Host Library. This document is split into the following sections:

## Overview

The USB Host Library (hereinafter referred to as the Host Library) is the lowest layer of the USB Host stack that exposes a public facing API. In most cases, applications that require USB Host functionality do not need to interface with the Host Library directly. Instead, most applications use the API provided by a host class driver that is implemented on top of the Host Library.

However, you may want to use the Host Library directly for some of (but not limited to) the following reasons:

- Implementation of a custom host class driver

- Usage of lower level USB Host API

### Features & Limitations

The Host Library has the following features:

- Supports High Speed (HS), Full Speed (FS) and Low Speed (LS) Devices.

- Supports all four transfer types: Control, Bulk, Interrupt, and Isochronous.

- Supports High-Bandwidth Isochronous endpoints.

- Allows multiple class drivers to run simultaneously, i.e., multiple clients of the Host Library.

- A single device can be used by multiple clients simultaneously, e.g., composite devices.

- The Host Library itself and the underlying Host Stack does not internally instantiate any OS tasks. The number of tasks is entirely controlled by how the Host Library interface is used. However, a general rule of thumb regarding the number of tasks is `(the number of host class drivers running + 1)`.

- Allows single Hub support (If option CONFIG_USB_HOST_HUBS_SUPPORTED is enabled).

- Allows multiple Hubs support (If option CONFIG_USB_HOST_HUB_MULTI_LEVEL is enabled).

Currently, the Host Library and the underlying Host Stack has the following limitations:

- Only supports Asynchronous transfers.

- Only supports using one configuration. Changing to other configurations after enumeration is not supported yet.

- Transfer timeouts are not supported yet.

- ESP32-P4 contains two USB-OTG peripherals USB 2.0 OTG High-Speed and USB 2.0 OTG Full-Speed. Only the High-Speed instance is supported now.

- The External Hub Driver: Remote Wakeup feature is not supported (External Hubs are active, even if there are no devices inserted).

- The External Hub Driver: Doesn't handle error cases (overcurrent handling, errors during initialization etc. are not implemented yet).

- The External Hub Driver: No Interface selection. The Driver uses the first available Interface with Hub Class code (09h).

- The External Port Driver: No downstream port debounce mechanism (not implemented yet)

- The External Hub Driver: No Transaction Translator layer (No FS/LS Devices support when a Hub is attached to HS Host).

## Architecture

Diagram of the key entities involved in USB Host functionality

The diagram above shows the key entities that are involved when implementing USB Host functionality. These entities are:

- The Host Library

- Clients of the Host Library

- Devices

- Host Library Daemon Task

### Host Library

The Host Library is the lowest public-facing API layer of the ESP-IDF USB Host Stack. Any other ESP-IDF component (such as a class driver or a user component) that needs to communicate with a connected USB device can only do so using the Host Library API either directly or indirectly.

The Host Library's API is split into two sub-sets, namely the Library API and Client API.

- The Client API handles the communication between a client of the Host Library and one or more USB devices. The Client API should only be called by registered clients of the Host Library.

- The Library API handles all of the Host Library processing that is not specific to a single client, such as device enumeration. Usually, the library API is called by a Host Library Daemon Task.

### Clients

A client of the Host Library is a software component, such as a host class driver or user component, which utilizes the Host Library to establish communication with a USB device. Generally, each client has a one-to-one relation with a task. This implies that all Client API calls pertaining to a specific client must originate from the context of the same task.

By organizing the software components that use the Host Library's into clients, the Host Library can delegate the handling of all events specific to that client to the client's task. In other words, each client task is responsible for all the required processing and event handling associated with the USB communication that the client initiates.

### Daemon Task

Although the Host Library delegates the handling of client events to the clients themselves, there are still Library events – events that are not specific to any particular client – that need to be handled. Library event handling can include things such as:

- Handling USB device connection, enumeration, and disconnection

- Rerouting control transfers to/from clients

- Forwarding events to clients

Therefore, in addition to the client tasks, the Host Library also requires a task, which is usually the Host Library Daemon Task, to handle all of the library events.

### Devices

The Host Library shields clients from the details of device handling, encompassing details such as connection, memory allocation, and enumeration. The clients are provided only with a list of already connected and enumerated devices to choose from. By default during enumeration, each device is automatically configured to use the first configuration found, namely, the first configuration descriptor returned on a Get Configuration Descriptor request. For most standard devices, the first configuration will have a `bConfigurationValue` of `1`. If option CONFIG_USB_HOST_ENABLE_ENUM_FILTER_CALLBACK is enabled, a different `bConfigurationValue` can be selected, see Multiple Configuration Support for more details.

It is possible for two or more clients to simultaneously communicate with the same device as long as they are not communicating to the same interface. However, multiple clients can simultaneously communicate with the same device's default endpoint (i.e., EP0), which will result in their control transfers being serialized.

For a client to communicate with a device, the client must:

1. Open the device using the device's address. This lets the Host Library know that the client is using that device.

2. Claim the interface(s) that will be used for communication. This prevents other clients from claiming the same interface(s).

3. Send transfers to the endpoints of claimed interfaces. The client's task is responsible for handling its own processing and events related to USB device communication.

## Usage

The Host Library and the underlying Host Stack will not create any tasks. All tasks, namely the client tasks and the Daemon Task, need to be created by the class drivers or the user. Instead, the Host Library provides two event handler functions that handle all of the required Host Library processing, thus these functions should be called repeatedly from the client tasks and the Daemon Task. Therefore, the implementation of client tasks and the Daemon Task will be largely centered around the invocation of these event handler functions.

### Host Library & Daemon Task

#### Basic Usage

The Host Library API provides `usb_host_lib_handle_events()` to handle library events. This function should be called repeatedly, typically from the Daemon Task. Some notable features regarding `usb_host_lib_handle_events()` are:

- The function can block until a library event needs handling.

- Event flags are returned on each invocation. These event flags are useful for knowing when the Host Library can be uninstalled.

A bare-bones Daemon Task would resemble something like the following code snippet:

    #include "usb/usb_host.h"

    void daemon_task(void *arg)
    {
        ...
        bool exit = false;
        while (!exit) {
            uint32_t event_flags;
            usb_host_lib_handle_events(portMAX_DELAY, &event_flags);
            if (event_flags & USB_HOST_LIB_EVENT_FLAGS_NO_CLIENTS) {
                ...
            }
            if (event_flags & USB_HOST_LIB_EVENT_FLAGS_ALL_FREE) {
                ...
            }
            ...
        }
        ...
    }

Note

See the peripherals/usb/host/usb_host_lib example for full implementation of the Daemon Task.

#### Lifecycle

Graph of Typical USB Host Library Lifecycle

The graph above illustrates the typical lifecycle of the Host Library with multiple clients and devices. Specifically, the example involves:

- Two registered clients (Client 1 and Client 2).

- Two connected devices (Device 1 and Device 2), where Client 1 communicates with Device 1 and Client 2 communicates with Device 2.

With reference to the graph above, the typical lifecycle involves the following key stages.

1. The Host Library is installed by calling `usb_host_install()`.

     - Installation must be done before any other Host Library API is called.

     - Where `usb_host_install()` is called (e.g., from the Daemon Task or another task) depends on the synchronization logic between the Daemon Task, client tasks, and the rest of the system.

2. Once the Host Library is installed, the clients can be registered by calling `usb_host_client_register()`.

     - This is typically called from the client task, where the client task waits for a signal from the Daemon Task.

     - This can be called elsewhere if necessary as long it is called after `usb_host_install()`.

3. Device 1 connects and is then enumerated.

     - Each registered client (in this case Client 1 and Client 2) is notified of the new device by way of the `USB_HOST_CLIENT_EVENT_NEW_DEV` event.

     - Client 1 opens Device 1 and begins communication with it.

4. Similarly Device 2 connects and is enumerated.

     - Client 1 and 2 are notified of a new device via a `USB_HOST_CLIENT_EVENT_NEW_DEV` event.

     - Client 2 opens Device 2 and begins communication with it.

5. Device 1 suddenly disconnects.

     - Client 1 is notified by way of `USB_HOST_CLIENT_EVENT_DEV_GONE` and begins its cleanup.

     - Client 2 is not notified as it has not opened Device 1.

6. Client 1 completes its cleanup and deregisters by calling `usb_host_client_deregister()`.

     - This is typically called from the client task before the task exits.

     - This can be called elsewhere if necessary as long as Client 1 has already completed its cleanup.

7. Client 2 completes its communication with Device 2. Client 2 then closes Device 2 and deregisters itself.

     - The Daemon Task is notified of the deregistration of all clients by way the `USB_HOST_LIB_EVENT_FLAGS_NO_CLIENTS` event flag as Client 2 is the last client to deregister.

     - Device 2 is still allocated (i.e., not freed), as it is still connected albeit not currently opened by any client.

8. The Daemon Task decides to clean up as there are no more clients.

     - The Daemon Task must free Device 2 first by calling `usb_host_device_free_all()`.

     - If `usb_host_device_free_all()` was able to free all devices, the function will return ESP_OK indicating that all devices have been freed.

     - If `usb_host_device_free_all()` was unable to free all devices for reasons like the device is still opened by a client, the function will return ESP_ERR_NOT_FINISHED.

     - The Daemon Task must wait for `usb_host_lib_handle_events()` to return the `USB_HOST_LIB_EVENT_FLAGS_ALL_FREE` event flag in order to know when all devices have been freed.

9. Once the Daemon Task has verified that all clients have deregistered and all devices have been freed, it can now uninstall the Host Library by calling `usb_host_uninstall()`.

### Clients & Class Driver

#### Basic Usage

The Host Library API provides `usb_host_client_handle_events()` to handle a particular client's events. This function should be called repeatedly, typically from the client's task. Some notable features regarding `usb_host_client_handle_events()` are:

- The function can block until a client event needs handling.

- The function's primary purpose is to call the various event handling callbacks when a client event occurs.

The following callbacks are called from within `usb_host_client_handle_events()` thus allowing the client task to be notified of events.

- The client event callback of type `usb_host_client_event_cb_t` delivers client event messages to the client. Client event messages indicate events such as the addition or removal of a device.

- The USB transfer completion callback of type `usb_transfer_cb_t` indicates that a particular USB transfer previously submitted by the client has been completed.

Note

Given that the callbacks are called from within `usb_host_client_handle_events()`, users should avoid blocking from within the callbacks as this will result in `usb_host_client_handle_events()` being blocked as well, thus preventing other pending client events from being handled.

The following code snippet demonstrates a bare-bones host class driver and its client task. The code snippet contains:

- A simple client task function `client_task` that calls `usb_host_client_handle_events()` in a loop.

- Implementations of a client event callback and transfer completion callbacks.

- Implementation of a simple state machine for the class driver. The class driver simply opens a device, sends an OUT transfer to EP1, then closes the device.

    #include <string.h>
    #include "usb/usb_host.h"

    #define CLASS_DRIVER_ACTION_OPEN_DEV    0x01
    #define CLASS_DRIVER_ACTION_TRANSFER    0x02
    #define CLASS_DRIVER_ACTION_CLOSE_DEV   0x03

    struct class_driver_control {
        uint32_t actions;
        uint8_t dev_addr;
        usb_host_client_handle_t client_hdl;
        usb_device_handle_t dev_hdl;
    };

    static void client_event_cb(const usb_host_client_event_msg_t *event_msg, void *arg)
    {
        // This function is called from within usb_host_client_handle_events(). Do not block and try to keep it short
        struct class_driver_control *class_driver_obj = (struct class_driver_control *)arg;
        switch (event_msg->event) {
            case USB_HOST_CLIENT_EVENT_NEW_DEV:
                class_driver_obj->actions |= CLASS_DRIVER_ACTION_OPEN_DEV;
                class_driver_obj->dev_addr = event_msg->new_dev.address; //Store the address of the new device
                break;
            case USB_HOST_CLIENT_EVENT_DEV_GONE:
                class_driver_obj->actions |= CLASS_DRIVER_ACTION_CLOSE_DEV;
                break;
            default:
                break;
        }
    }

    static void transfer_cb(usb_transfer_t *transfer)
    {
        // This function is called from within usb_host_client_handle_events(). Do not block and try to keep it short
        struct class_driver_control *class_driver_obj = (struct class_driver_control *)transfer->context;
        printf("Transfer status %d, actual number of bytes transferred %d\n", transfer->status, transfer->actual_num_bytes);
        class_driver_obj->actions |= CLASS_DRIVER_ACTION_CLOSE_DEV;
    }

    void client_task(void *arg)
    {
        ... // Wait until Host Library is installed
        // Initialize class driver objects
        struct class_driver_control class_driver_obj = {0};
        // Register the client
        usb_host_client_config_t client_config = {
            .is_synchronous = false,
            .max_num_event_msg = 5,
            .async = {
                .client_event_callback = client_event_cb,
                .callback_arg = &class_driver_obj,
            }
        };
        usb_host_client_register(&client_config, &class_driver_obj.client_hdl);
        //Allocate a USB transfer
        usb_transfer_t *transfer;
        usb_host_transfer_alloc(1024, 0, &transfer);

        //Event handling loop
        bool exit = false;
        while (!exit) {
            // Call the client event handler function
            usb_host_client_handle_events(class_driver_obj.client_hdl, portMAX_DELAY);
            // Execute pending class driver actions
            if (class_driver_obj.actions & CLASS_DRIVER_ACTION_OPEN_DEV) {
                // Open the device and claim interface 1
                usb_host_device_open(class_driver_obj.client_hdl, class_driver_obj.dev_addr, &class_driver_obj.dev_hdl);
                usb_host_interface_claim(class_driver_obj.client_hdl, class_driver_obj.dev_hdl, 1, 0);
            }
            if (class_driver_obj.actions & CLASS_DRIVER_ACTION_TRANSFER) {
                // Send an OUT transfer to EP1
                memset(transfer->data_buffer, 0xAA, 1024);
                transfer->num_bytes = 1024;
                transfer->device_handle = class_driver_obj.dev_hdl;
                transfer->bEndpointAddress = 0x01;
                transfer->callback = transfer_cb;
                transfer->context = (void *)&class_driver_obj;
                usb_host_transfer_submit(transfer);
            }
            if (class_driver_obj.actions & CLASS_DRIVER_ACTION_CLOSE_DEV) {
                // Release the interface and close the device
                usb_host_interface_release(class_driver_obj.client_hdl, class_driver_obj.dev_hdl, 1);
                usb_host_device_close(class_driver_obj.client_hdl, class_driver_obj.dev_hdl);
                exit = true;
            }
            ... // Handle any other actions required by the class driver
        }

        // Cleanup class driver
        usb_host_transfer_free(transfer);
        usb_host_client_deregister(class_driver_obj.client_hdl);
        ... // Delete the client task. Signal the Daemon Task if necessary.
    }

Note

An actual host class driver is likely to support many more features, thus will have a much more complex state machine. A host class driver is also likely to need to:

- Be able to open multiple devices

- Parse an opened device's descriptors to identify if the device is of the target class

- Communicate with multiple endpoints of an interface in a particular order

- Claim multiple interfaces of a device

- Handle various errors

#### Lifecycle

The typical life cycle of a client task and class driver will go through the following stages:

1. Wait for some signal regarding the Host Library being installed.

2. Register the client via `usb_host_client_register()` and allocate any other class driver resources, such as allocating transfers using `usb_host_transfer_alloc()`.

3. For each new device that the class driver needs to communicate with:

   > 1. Check if the device is already connected via `usb_host_device_addr_list_fill()`.

   > 2. If the device is not already connected, wait for a `USB_HOST_CLIENT_EVENT_NEW_DEV` event from the client event callback.

   > 3. Open the device via `usb_host_device_open()`.

   > 4. Parse the device and configuration descriptors via `usb_host_get_device_descriptor()` and `usb_host_get_active_config_descriptor()` respectively.

   > 5. Claim the necessary interfaces of the device via `usb_host_interface_claim()`.

4. Submit transfers to the device via `usb_host_transfer_submit()` or `usb_host_transfer_submit_control()`.

5. Once an opened device is no longer needed by the class driver, or has disconnected, as indicated by a `USB_HOST_CLIENT_EVENT_DEV_GONE` event:

   > 1. Stop any previously submitted transfers to the device's endpoints by calling `usb_host_endpoint_halt()` and `usb_host_endpoint_flush()` on those endpoints.

   > 2. Release all previously claimed interfaces via `usb_host_interface_release()`.

   > 3. Close the device via `usb_host_device_close()`.

6. Deregister the client via `usb_host_client_deregister()` and free any other class driver resources.

7. Delete the client task. Signal the Daemon Task if necessary.

## Examples

### Host Library Examples

- peripherals/usb/host/usb_host_lib demonstrates how to use the USB Host Library API to install and register a client, wait for a device connection, print the device's information, handle disconnection, and repeat these steps until a user quits the application.

### Class Driver Examples

The USB Host Stack provides a number of examples that implement host class drivers using the Host Library's API.

#### CDC-ACM

- A host class driver for the Communication Device Class (Abstract Control Model) is distributed as a managed component via the ESP Component Registry.

- peripherals/usb/host/cdc/cdc_acm_host demonstrates how to use the CDC-ACM Host Driver to enable communication between ESP32-P4 and a USB CDC-ACM device.

- peripherals/usb/host/cdc/cdc_acm_vcp demonstrates how to extend the CDC-ACM driver for Virtual Communication Port (VCP) devices like CP210x, FTDI FT23x or CH34x devices, and how to control the device and send data using the CDC-ACM API.

- The CDC-ACM driver is also used in esp_modem examples, where it is used for communication with cellular modems.

#### MSC

- A host class driver for the Mass Storage Class (Bulk-Only Transport) is deployed to ESP Component Registry.

- peripherals/usb/host/msc demonstrates how to use USB Mass Storage Class to access, read, write, and perform operations on a USB flash drive, including handling USB reconnections and deinitializing the USB Host Stack.

#### HID

- A host class driver for the HID (Human interface device) is distributed as a managed component via the ESP Component Registry.

- peripherals/usb/host/hid demonstrates how to implement a basic USB Host HID Class Driver on ESP32-P4, enabling communication with USB HID devices like keyboards and mice, and continuously scans for their connection, fetching HID reports once connected.

#### UVC

- A host class driver for the USB Video Device Class is distributed as a managed component via the ESP Component Registry.

- peripherals/usb/host/uvc demonstrates how to capture video frames from a USB camera using the UVC driver.

## Host Stack Configuration

### Non-Compliant Device Support

To support USB devices that are non-compliant in various scenarios or exhibit specific behaviors, it is possible to configure the USB Host stack.

As a USB device may be hot-plugged, it is essential to have configurable delays between power switching and device attachment, and when the device's internal power has stabilized.

#### Enumeration Configuration

During the process of enumerating connected USB devices, several delay values ensure the proper functioning of the device.

USB Root Hub Power-on and Connection Events Timing

The figure above shows all the delay values associated with both turning on port power with a device connected and hot-plugging a device.

- After a port is reset or resumed, the USB system software is expected to provide a "recovery" interval of 10 ms before the device attached to the port is expected to respond to data transfers.

- After the reset/resume recovery interval, if a device receives a `SetAddress()` request, the device must be able to complete processing of the request and be able to successfully complete the Status stage of the request within 50 ms.

- After successful completion of the Status stage, the device is allowed a `SetAddress()` recovery interval of 2 ms.

Note

For more details regarding connection event timings, please refer to USB 2.0 Specification > Chapter 7.1.7.3 Connect and Disconnect Signaling.

Configurable parameters of the USB host stack can be configured with multiple options via Menuconfig.

- For debounce delay, refer to CONFIG_USB_HOST_DEBOUNCE_DELAY_MS.

- For reset hold interval, refer to CONFIG_USB_HOST_RESET_HOLD_MS.

- For reset recovery interval, refer to CONFIG_USB_HOST_RESET_RECOVERY_MS.

- For `SetAddress()` recovery interval, refer to CONFIG_USB_HOST_SET_ADDR_RECOVERY_MS.

### Downstream Port Configuration

When external Hubs feature is supported, there are several parameters which could be configured for the external Hubs port.

Each external Hub has a Hub Descriptor which describes the device characteristics.

Note

For detailed information about Hub Descriptor, please refer to USB 2.0 Specification > Chapter 11.23.2.1 Hub Descriptor.

Configurable parameters of the downstream port can be configured with multiple options via Menuconfig.

- For custom value to stabilize the power after powering on the port (PwrOn2PwrGood value), refer to CONFIG_USB_HOST_EXT_PORT_CUSTOM_POWER_ON_DELAY_MS.

- For reset recovery interval, refer to CONFIG_USB_HOST_EXT_PORT_RESET_RECOVERY_DELAY_MS.

Note

The specification claims, that for a hub with no power switches, PwrOn2PwrGood must be set to zero. Meanwhile, for some devices, this value could be increased to give extra time for device to power-up. To enable this feature, refer to CONFIG_USB_HOST_EXT_PORT_CUSTOM_POWER_ON_DELAY_ENABLE.

#### Host Channels

When external Hubs support feature is enabled (CONFIG_USB_HOST_HUBS_SUPPORTED), the amount of Host channels plays important role, as each downstream device requires vacant channel.

To handle each attached device, different amount of channels are required. This amount does depend on the device class (EPs number).

Supported amount of channels for ESP32-P4 is 16.

Note

- One free channel is required to enumerate the device.

- From 1 to N (when N - number of EPs) free channels are required to claim the interface.

- When there are no more free Host channels available, the device could not be enumerated and its interface cannot be claimed.

### Multiple Configuration Support

To support USB devices that have more than one configuration, it is possible to specify the desired configuration number during a device's enumeration process.

#### Enumeration Filter

The enumeration filter is a callback function of type `usb_host_enum_filter_cb_t` called at the beginning of the enumeration process once a device descriptor is read from a newly attached USB device. Consequently, the user is provided with the obtained device descriptor. Through this callback, the user can:

- Select the configuration of the USB device.

- Filter which USB devices should be enumerated.

To use the enumeration filter, users should enable the CONFIG_USB_HOST_ENABLE_ENUM_FILTER_CALLBACK option using menuconfig. Users can specify the callback by setting `usb_host_config_t::enum_filter_cb` which is then passed to the Host Library when calling `usb_host_install()`.

## API Reference

The API of the USB Host Library is separated into the following header files. However, it is sufficient for applications to only `#include "usb/usb_host.h"` and all USB Host Library headers will also be included.

- usb/include/usb/usb_host.h contains the functions and types of the USB Host Library.

- usb/include/usb/usb_helpers.h contains various helper functions that are related to the USB protocol such as descriptor parsing.

- usb/include/usb/usb_types_stack.h contains types that are used across multiple layers of the USB Host stack.

- usb/include/usb/usb_types_ch9.h contains types and macros related to Chapter 9 of the USB2.0 specification, i.e., descriptors and standard requests.

### Header File

- components/usb/include/usb/usb_host.h

- This header file can be included with:

  >     #include "usb/usb_host.h"

- This header file is a part of the API provided by the `usb` component. To declare that your component depends on `usb`, add the following to your CMakeLists.txt:

  >     REQUIRES usb

  > or

  >     PRIV_REQUIRES usb

### Functions

esp_err_t usb_host_install(const usb_host_config_t *config)

  Install the USB Host Library.

  - This function should be called only once to install the USB Host Library

  - This function should be called before any other USB Host Library functions are called

  Note

  If skip_phy_setup is set in the install configuration, the user is responsible for ensuring that the underlying Host Controller is enabled and the USB PHY (internal or external) is already setup before this function is called.

  Parameters:

    config -- [in] USB Host Library configuration

  Returns:

    - ESP_OK: USB Host installed successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_INVALID_STATE: USB Host Library is not in correct state to be installed (eg. the library itself of one of it's drivers is already installed)

    - ESP_ERR_NO_MEM: Insufficient memory

esp_err_t usb_host_uninstall(void)

  Uninstall the USB Host Library.

  - This function should be called to uninstall the USB Host Library, thereby freeing its resources

  - All clients must have been deregistered before calling this function

  - All devices must have been freed by calling usb_host_device_free_all() and receiving the USB_HOST_LIB_EVENT_FLAGS_ALL_FREE event flag

  Note

  If skip_phy_setup was set when the Host Library was installed, the user is responsible for disabling the underlying Host Controller and USB PHY (internal or external).

  Returns:

    - ESP_OK: USB Host uninstalled successfully

    - ESP_ERR_INVALID_STATE: USB Host Library is not installed, or has unfinished actions

esp_err_t usb_host_lib_handle_events(TickType_t timeout_ticks, uint32_t *event_flags_ret)

  Handle USB Host Library events.

  - This function handles all of the USB Host Library's processing and should be called repeatedly in a loop

  - Check event_flags_ret to see if an flags are set indicating particular USB Host Library events

  - This function should never be called by multiple threads simultaneously

  Note

  This function can block

  Parameters:

    - timeout_ticks -- [in] Timeout in ticks to wait for an event to occur

    - event_flags_ret -- [out] Event flags that indicate what USB Host Library event occurred.

  Returns:

    - ESP_OK: No events to be handled

    - ESP_ERR_INVALID_STATE: USB Host Library is not installed

    - ESP_ERR_TIMEOUT: Semaphore waiting for events has timed out

esp_err_t usb_host_lib_unblock(void)

  Unblock the USB Host Library handler.

  - This function simply unblocks the USB Host Library event handling function (usb_host_lib_handle_events())

  Returns:

    - ESP_OK: USB Host library unblocked successfully

    - ESP_ERR_INVALID_STATE: USB Host Library is not installed

esp_err_t usb_host_lib_info(usb_host_lib_info_t *info_ret)

  Get current information about the USB Host Library.

  Parameters:

    info_ret -- [out] USB Host Library Information

  Returns:

    - ESP_OK: USB Host Library info obtained successfully

    - ESP_ERR_INVALID_STATE: USB Host Library is not installed

    - ESP_ERR_INVALID_ARG: Invalid argument

esp_err_t usb_host_lib_set_root_port_power(bool enable)

  Power the root port ON or OFF.

  - Powering ON the root port will allow device connections to occur

  - Powering OFF the root port will disconnect all devices downstream off the root port and prevent any further device connections.

  Note

  If 'usb_host_config_t.root_port_unpowered' was set on USB Host Library installation, users must call this function to power ON the root port before any device connections can occur.

  Parameters:

    enable -- [in] True to power the root port ON, false to power OFF

  Returns:

    - ESP_OK: Root port power enabled/disabled

    - ESP_ERR_INVALID_STATE: Root port already powered or HUB driver not installed

esp_err_t usb_host_client_register(const usb_host_client_config_t *client_config, usb_host_client_handle_t *client_hdl_ret)

  Register a client of the USB Host Library.

  - This function registers a client of the USB Host Library

  - Once a client is registered, its processing function usb_host_client_handle_events() should be called repeatedly

  Parameters:

    - client_config -- [in] Client configuration

    - client_hdl_ret -- [out] Client handle

  Returns:

    - ESP_OK: USB Host Library client registered successfully

    - ESP_ERR_INVALID_STATE: USB Host Library is not installed

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_NO_MEM: Insufficient memory

esp_err_t usb_host_client_deregister(usb_host_client_handle_t client_hdl)

  Deregister a USB Host Library client.

  - This function deregisters a client of the USB Host Library

  - The client must have closed all previously opened devices before attempting to deregister

  Parameters:

    client_hdl -- [in] Client handle

  Returns:

    - ESP_OK: USB Host Library client deregistered successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

esp_err_t usb_host_client_handle_events(usb_host_client_handle_t client_hdl, TickType_t timeout_ticks)

  USB Host Library client processing function.

  - This function handles all of a client's processing and should be called repeatedly in a loop

  - For a particular client, this function should never be called by multiple threads simultaneously

  Note

  This function can block

  Parameters:

    - client_hdl -- [in] Client handle

    - timeout_ticks -- [in] Timeout in ticks to wait for an event to occur

  Returns:

    - ESP_OK: No event to be handled

    - ESP_ERR_INVALID_STATE: USB Host Library is not installed

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_TIMEOUT: Semaphore waiting for events has timed out

esp_err_t usb_host_client_unblock(usb_host_client_handle_t client_hdl)

  Unblock a client.

  - This function simply unblocks a client if it is blocked on the usb_host_client_handle_events() function.

  - This function is useful when need to unblock a client in order to deregister it.

  Parameters:

    client_hdl -- [in] Client handle

  Returns:

    - ESP_OK: Client unblocked successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

esp_err_t usb_host_device_open(usb_host_client_handle_t client_hdl, uint8_t dev_addr, usb_device_handle_t *dev_hdl_ret)

  Open a device.

  - This function allows a client to open a device

  - A client must open a device first before attempting to use it (e.g., sending transfers, device requests etc.)

  Parameters:

    - client_hdl -- [in] Client handle

    - dev_addr -- [in] Device's address

    - dev_hdl_ret -- [out] Device's handle

  Returns:

    - ESP_OK: Device opened successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

esp_err_t usb_host_device_close(usb_host_client_handle_t client_hdl, usb_device_handle_t dev_hdl)

  Close a device.

  - This function allows a client to close a device

  - A client must close a device after it has finished using the device (claimed interfaces must also be released)

  - A client must close all devices it has opened before de-registering

  Note

  This function can block

  Parameters:

    - client_hdl -- [in] Client handle

    - dev_hdl -- [in] Device handle

  Returns:

    - ESP_OK: Device closed successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_NOT_FOUND: The client never opened the device (the device address not found among opened devices)

    - ESP_ERR_INVALID_STATE: The client has not released all interfaces from the device

esp_err_t usb_host_device_free_all(void)

  Indicate that all devices can be freed when possible.

  - This function marks all devices as waiting to be freed

  - If a device is not opened by any clients, it will be freed immediately

  - If a device is opened by at least one client, the device will be free when the last client closes that device.

  - Wait for the USB_HOST_LIB_EVENT_FLAGS_ALL_FREE flag to be set by usb_host_lib_handle_events() in order to know when all devices have been freed

  - This function is useful when cleaning up devices before uninstalling the USB Host Library

  Returns:

    - ESP_OK: All devices already freed (i.e., there were no devices)

    - ESP_ERR_INVALID_STATE: Client must be deregistered

    - ESP_ERR_NOT_FINISHED: There are one or more devices that still need to be freed, wait for USB_HOST_LIB_EVENT_FLAGS_ALL_FREE event

esp_err_t usb_host_device_addr_list_fill(int list_len, uint8_t *dev_addr_list, int *num_dev_ret)

  Fill a list of device address.

  - This function fills an empty list with the address of connected devices

  - The Device addresses can then used in usb_host_device_open()

  - If there are more devices than the list_len, this function will only fill up to list_len number of devices.

  Parameters:

    - list_len -- [in] Length of the empty list

    - dev_addr_list -- [inout] Empty list to be filled

    - num_dev_ret -- [out] Number of devices

  Returns:

    - ESP_OK: Device list filled successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

esp_err_t usb_host_device_info(usb_device_handle_t dev_hdl, usb_device_info_t *dev_info)

  Get device's information.

  - This function gets some basic information of a device

  - The device must be opened first before attempting to get its information

  Note

  This function can block

  Parameters:

    - dev_hdl -- [in] Device handle

    - dev_info -- [out] Device information

  Returns:

    - ESP_OK: Device information obtained successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

esp_err_t usb_host_get_device_descriptor(usb_device_handle_t dev_hdl, const usb_device_desc_t **device_desc)

  Get device's device descriptor.

  - A client must call usb_host_device_open() first

  - No control transfer is sent. The device's descriptor is cached on enumeration

  - This function simple returns a pointer to the cached descriptor

  Note

  No control transfer is sent. The device's descriptor is cached on enumeration

  Parameters:

    - dev_hdl -- [in] Device handle

    - device_desc -- [out] Device descriptor

  Returns:

    - ESP_OK: Device descriptor obtained successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

esp_err_t usb_host_get_active_config_descriptor(usb_device_handle_t dev_hdl, const usb_config_desc_t **config_desc)

  Get device's active configuration descriptor.

  - A client must call usb_host_device_open() first

  - No control transfer is sent. The device's active configuration descriptor is cached on enumeration

  - This function simple returns a pointer to the cached descriptor

  Note

  This function can block

  Note

  No control transfer is sent. A device's active configuration descriptor is cached on enumeration

  Parameters:

    - dev_hdl -- [in] Device handle

    - config_desc -- [out] Configuration descriptor

  Returns:

    - ESP_OK: Active configuration descriptor obtained successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

esp_err_t usb_host_get_config_desc(usb_host_client_handle_t client_hdl, usb_device_handle_t dev_hdl, uint8_t bConfigurationValue, const usb_config_desc_t **config_desc_ret)

  Get get device's configuration descriptor.

  - The USB Host library only caches a device's active configuration descriptor.

  - This function reads any configuration descriptor of a particular device (specified by bConfigurationValue).

  - This function will read the specified configuration descriptor via control transfers, and allocate memory to store that descriptor.

  - Users can call usb_host_free_config_desc() to free the descriptor's memory afterwards.

  Note

  This function can block

  Note

  A client must call usb_host_device_open() on the device first

  Note

  bConfigurationValue starts from index 1

  Parameters:

    - client_hdl -- [in] Client handle - usb_host_client_handle_events() should be called repeatedly in a separate task to handle client events

    - dev_hdl -- [in] Device handle

    - bConfigurationValue -- [in] Index of device's configuration descriptor to be read

    - config_desc_ret -- [out] Returned configuration descriptor

  Returns:

    - ESP_OK: Configuration descriptor obtained successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_NOT_SUPPORTED: Invalid bConfigurationValue value (the device does not have this configuration value)

    - ESP_ERR_NO_MEM: Insufficient memory

esp_err_t usb_host_free_config_desc(const usb_config_desc_t *config_desc)

  Free a configuration descriptor.

  This function frees a configuration descriptor that was returned by usb_host_get_config_desc()

  Parameters:

    config_desc -- [out] Configuration descriptor

  Returns:

    - ESP_OK: Configuration descriptor freed successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

esp_err_t usb_host_interface_claim(usb_host_client_handle_t client_hdl, usb_device_handle_t dev_hdl, uint8_t bInterfaceNumber, uint8_t bAlternateSetting)

  Function for a client to claim a device's interface.

  - A client must claim a device's interface before attempting to communicate with any of its endpoints

  - Once an interface is claimed by a client, it cannot be claimed by any other client.

  Note

  This function can block

  Parameters:

    - client_hdl -- [in] Client handle

    - dev_hdl -- [in] Device handle

    - bInterfaceNumber -- [in] Interface number

    - bAlternateSetting -- [in] Interface alternate setting number

  Returns:

    - ESP_OK: Interface claimed successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_INVALID_STATE: USB Host is not a correct state to claim an interface

    - ESP_ERR_NOT_FOUND: Interface or EP not found

    - ESP_ERR_NO_MEM: Insufficient memory

esp_err_t usb_host_interface_release(usb_host_client_handle_t client_hdl, usb_device_handle_t dev_hdl, uint8_t bInterfaceNumber)

  Function for a client to release a previously claimed interface.

  - A client should release a device's interface after it no longer needs to communicate with the interface

  - A client must release all of its interfaces of a device it has claimed before being able to close the device

  Note

  This function can block

  Parameters:

    - client_hdl -- [in] Client handle

    - dev_hdl -- [in] Device handle

    - bInterfaceNumber -- [in] Interface number

  Returns:

    - ESP_OK: Interface released successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_INVALID_STATE: Client never opened the USB Device, or interface currently can not be freed

    - ESP_ERR_NOT_FOUND: Interface number not found in the list of interfaces

esp_err_t usb_host_endpoint_halt(usb_device_handle_t dev_hdl, uint8_t bEndpointAddress)

  Halt a particular endpoint.

  - The device must have been opened by a client

  - The endpoint must be part of an interface claimed by a client

  - Once halted, the endpoint must be cleared using usb_host_endpoint_clear() before it can communicate again

  Note

  This function can block

  Parameters:

    - dev_hdl -- [in] Device handle

    - bEndpointAddress -- [in] Endpoint address

  Returns:

    - ESP_OK: Endpoint halted successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_NOT_FOUND: Endpoint address not found

    - ESP_ERR_INVALID_STATE: Endpoint pipe is not in the correct state/condition to execute a command

esp_err_t usb_host_endpoint_flush(usb_device_handle_t dev_hdl, uint8_t bEndpointAddress)

  Flush a particular endpoint.

  - The device must have been opened by a client

  - The endpoint must be part of an interface claimed by a client

  - The endpoint must have been halted (either through a transfer error, or usb_host_endpoint_halt())

  - Flushing an endpoint will caused an queued up transfers to be canceled

  Note

  This function can block

  Parameters:

    - dev_hdl -- [in] Device handle

    - bEndpointAddress -- [in] Endpoint address

  Returns:

    - ESP_OK: Endpoint flushed successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_NOT_FOUND: Endpoint address not found

    - ESP_ERR_INVALID_STATE: Endpoint pipe is not in the correct state/condition to execute a command

esp_err_t usb_host_endpoint_clear(usb_device_handle_t dev_hdl, uint8_t bEndpointAddress)

  Clear a halt on a particular endpoint.

  - The device must have been opened by a client

  - The endpoint must be part of an interface claimed by a client

  - The endpoint must have been halted (either through a transfer error, or usb_host_endpoint_halt())

  - If the endpoint has any queued up transfers, clearing a halt will resume their execution

  Note

  This function can block

  Parameters:

    - dev_hdl -- [in] Device handle

    - bEndpointAddress -- [in] Endpoint address

  Returns:

    - ESP_OK: Endpoint cleared successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_NOT_FOUND: Endpoint address not found

    - ESP_ERR_INVALID_STATE: Endpoint pipe is not in the correct state/condition to execute a command

esp_err_t usb_host_transfer_alloc(size_t data_buffer_size, int num_isoc_packets, usb_transfer_t **transfer)

  Allocate a transfer object.

  - This function allocates a transfer object

  - Each transfer object has a fixed sized buffer specified on allocation

  - The resulting data_buffer_size can be bigger that the requested size. This is to ensure that the data buffer is cache aligned

  - A transfer object can be re-used indefinitely

  - A transfer can be submitted using usb_host_transfer_submit() or usb_host_transfer_submit_control()

  Parameters:

    - data_buffer_size -- [in] Size of the transfer's data buffer

    - num_isoc_packets -- [in] Number of isochronous packets in transfer (set to 0 for non-isochronous transfers)

    - transfer -- [out] Transfer object

  Returns:

    - ESP_OK: Transfer object allocated successfully

    - ESP_ERR_NO_MEM: Insufficient memory

esp_err_t usb_host_transfer_free(usb_transfer_t *transfer)

  Free a transfer object.

  - Free a transfer object previously allocated using usb_host_transfer_alloc()

  - The transfer must not be in-flight when attempting to free it

  - If a NULL pointer is passed, this function will simply return ESP_OK

  Parameters:

    transfer -- [in] Transfer object

  Returns:

    - ESP_OK: Transfer object freed successfully

esp_err_t usb_host_transfer_submit(usb_transfer_t *transfer)

  Submit a non-control transfer.

  - Submit a transfer to a particular endpoint. The device and endpoint number is specified inside the transfer

  - The transfer must be properly initialized before submitting

  - On completion, the transfer's callback will be called from the client's usb_host_client_handle_events() function.

  Parameters:

    transfer -- [in] Initialized transfer object

  Returns:

    - ESP_OK: Transfer submitted successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_NOT_FINISHED: Transfer already in-flight

    - ESP_ERR_NOT_FOUND: Endpoint address not found

    - ESP_ERR_INVALID_STATE: Endpoint pipe is not in a correct state to submit transfer

esp_err_t usb_host_transfer_submit_control(usb_host_client_handle_t client_hdl, usb_transfer_t *transfer)

  Submit a control transfer.

  - Submit a control transfer to a particular device. The client must have opened the device first

  - The transfer must be properly initialized before submitting. The first 8 bytes of the transfer's data buffer should contain the control transfer setup packet

  - On completion, the transfer's callback will be called from the client's usb_host_client_handle_events() function.

  Parameters:

    - client_hdl -- [in] Client handle

    - transfer -- [in] Initialized transfer object

  Returns:

    - ESP_OK: Control transfer submitted successfully

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_NOT_FINISHED: Transfer already in-flight

    - ESP_ERR_NOT_FOUND: Endpoint address not found

    - ESP_ERR_INVALID_STATE: Endpoint pipe is not in a correct state to submit transfer

### Structures

struct usb_host_client_event_msg_t

  Client event message.

  Client event messages are sent to each client of the USB Host Library in order to notify them of various USB Host Library events such as:

  - Addition of new devices

  - Removal of existing devices

  Note

  The event message structure has a union with members corresponding to each particular event. Based on the event type, only the relevant member field should be accessed.

  Public Members

  usb_host_client_event_t event

    Type of event

  uint8_t address

    New device's address

  struct usb_host_client_event_msg_t new_dev

    New device info

  usb_device_handle_t dev_hdl

    The handle of the device that was gone

  struct usb_host_client_event_msg_t dev_gone

    Gone device info

struct usb_host_lib_info_t

  Current information about the USB Host Library obtained via usb_host_lib_info()

  Public Members

  int num_devices

    Current number of connected (and enumerated) devices

  int num_clients

    Current number of registered clients

struct usb_host_config_t

  USB Host Library configuration.

  Configuration structure of the USB Host Library. Provided in the usb_host_install() function

  Public Members

  bool skip_phy_setup

    If set, the USB Host Library will not configure the USB PHY thus allowing the user to manually configure the USB PHY before calling usb_host_install(). Users should set this if they want to use an external USB PHY. Otherwise, the USB Host Library will automatically configure the internal USB PHY

  bool root_port_unpowered

    If set, the USB Host Library will not power on the root port on installation. This allows users to power on the root port manually by calling usb_host_lib_set_root_port_power().

  int intr_flags

    Interrupt flags for the underlying ISR used by the USB Host stack

  usb_host_enum_filter_cb_t enum_filter_cb

    Enumeration filter callback. Enable CONFIG_USB_HOST_ENABLE_ENUM_FILTER_CALLBACK to use this feature. Set to NULL otherwise.

  uint32_t nptx_fifo_lines

    Required: Number of non-periodic TX FIFO lines. Must be > 0 to enable custom configuration.

  uint32_t ptx_fifo_lines

    Optional: Number of periodic TX FIFO lines. Can be 0 if periodic TX endpoints are not used.

  uint32_t rx_fifo_lines

    Required: Number of RX FIFO lines. Must be > 0 to enable custom configuration.

  struct usb_host_config_t fifo_settings_custom

    Optional custom FIFO configuration (advanced use). RX and NPTX must be > 0. If all fields are zero, a default configuration will be selected based on Kconfig bias.

struct usb_host_client_config_t

  USB Host Library Client configuration.

  Configuration structure for a USB Host Library client. Provided in usb_host_client_register()

  Public Members

  bool is_synchronous

    Whether the client is asynchronous or synchronous or not. Set to false for now.

  int max_num_event_msg

    Maximum number of event messages that can be stored (e.g., 3)

  usb_host_client_event_cb_t client_event_callback

    Client's event callback function

  void *callback_arg

    Event callback function argument

  struct usb_host_client_config_t async

    Async callback config

### Macros

USB_HOST_LIB_EVENT_FLAGS_NO_CLIENTS

  All clients have been deregistered from the USB Host Library

USB_HOST_LIB_EVENT_FLAGS_ALL_FREE

  The USB Host Library has freed all devices

### Type Definitions

typedef struct usb_host_client_handle_s *usb_host_client_handle_t

  Handle to a USB Host Library asynchronous client.

  An asynchronous client can be registered using usb_host_client_register()

  Note

  Asynchronous API

typedef void (*usb_host_client_event_cb_t)(const usb_host_client_event_msg_t *event_msg, void *arg)

  Client event callback.

  - Each client of the USB Host Library must register an event callback to receive event messages from the USB Host Library.

  - The client event callback is run from the context of the clients usb_host_client_handle_events() function

### Enumerations

enum usb_host_client_event_t

  The type event in a client event message.

  Values:

  enumerator USB_HOST_CLIENT_EVENT_NEW_DEV

    A new device has been enumerated and added to the USB Host Library

  enumerator USB_HOST_CLIENT_EVENT_DEV_GONE

    A device opened by the client is now gone

### Header File

- components/usb/include/usb/usb_helpers.h

- This header file can be included with:

  >     #include "usb/usb_helpers.h"

- This header file is a part of the API provided by the `usb` component. To declare that your component depends on `usb`, add the following to your CMakeLists.txt:

  >     REQUIRES usb

  > or

  >     PRIV_REQUIRES usb

### Functions

const usb_standard_desc_t *usb_parse_next_descriptor(const usb_standard_desc_t *cur_desc, uint16_t wTotalLength, int *offset)

  Get the next descriptor.

  Given a particular descriptor within a full configuration descriptor, get the next descriptor within the configuration descriptor. This is a convenience function that can be used to walk each individual descriptor within a full configuration descriptor.

  Parameters:

    - cur_desc -- [in] Current descriptor

    - wTotalLength -- [in] Total length of the configuration descriptor

    - offset -- [inout] Byte offset relative to the start of the configuration descriptor. On input, it is the offset of the current descriptor. On output, it is the offset of the returned descriptor.

  Returns:

    usb_standard_desc_t* Next descriptor, NULL if end of configuration descriptor reached

const usb_standard_desc_t *usb_parse_next_descriptor_of_type(const usb_standard_desc_t *cur_desc, uint16_t wTotalLength, uint8_t bDescriptorType, int *offset)

  Get the next descriptor of a particular type.

  Given a particular descriptor within a full configuration descriptor, get the next descriptor of a particular type (i.e., using the bDescriptorType value) within the configuration descriptor.

  Parameters:

    - cur_desc -- [in] Current descriptor

    - wTotalLength -- [in] Total length of the configuration descriptor

    - bDescriptorType -- [in] Type of the next descriptor to get

    - offset -- [inout] Byte offset relative to the start of the configuration descriptor. On input, it is the offset of the current descriptor. On output, it is the offset of the returned descriptor.

  Returns:

    usb_standard_desc_t* Next descriptor, NULL if end descriptor is not found or configuration descriptor reached

int usb_parse_interface_number_of_alternate(const usb_config_desc_t *config_desc, uint8_t bInterfaceNumber)

  Get the number of alternate settings for a bInterfaceNumber.

  Given a particular configuration descriptor, for a particular bInterfaceNumber, get the number of alternate settings available for that interface (i.e., the max possible value of bAlternateSetting for that bInterfaceNumber).

  Parameters:

    - config_desc -- [in] Pointer to the start of a full configuration descriptor

    - bInterfaceNumber -- [in] Interface number

  Returns:

    int The number of alternate settings that the interface has, -1 if bInterfaceNumber not found

const usb_intf_desc_t *usb_parse_interface_descriptor(const usb_config_desc_t *config_desc, uint8_t bInterfaceNumber, uint8_t bAlternateSetting, int *offset)

  Get a particular interface descriptor (using bInterfaceNumber and bAlternateSetting)

  Given a full configuration descriptor, get a particular interface descriptor.

  Note

  To get the number of alternate settings for a particular bInterfaceNumber, call usb_parse_interface_number_of_alternate()

  Parameters:

    - config_desc -- [in] Pointer to the start of a full configuration descriptor

    - bInterfaceNumber -- [in] Interface number

    - bAlternateSetting -- [in] Alternate setting number

    - offset -- [out] Byte offset of the interface descriptor relative to the start of the configuration descriptor. Can be NULL.

  Returns:

    const usb_intf_desc_t* Pointer to interface descriptor, NULL if not found.

const usb_ep_desc_t *usb_parse_endpoint_descriptor_by_index(const usb_intf_desc_t *intf_desc, int index, uint16_t wTotalLength, int *offset)

  Get an endpoint descriptor within an interface descriptor.

  Given an interface descriptor, get the Nth endpoint descriptor of the interface. The number of endpoints in an interface is indicated by the bNumEndpoints field of the interface descriptor.

  Note

  If bNumEndpoints is 0, it means the interface uses the default endpoint only

  Parameters:

    - intf_desc -- [in] Pointer to thee start of an interface descriptor

    - index -- [in] Endpoint index

    - wTotalLength -- [in] Total length of the containing configuration descriptor

    - offset -- [inout] Byte offset relative to the start of the configuration descriptor. On input, it is the offset of the interface descriptor. On output, it is the offset of the endpoint descriptor.

  Returns:

    const usb_ep_desc_t* Pointer to endpoint descriptor, NULL if not found.

const usb_ep_desc_t *usb_parse_endpoint_descriptor_by_address(const usb_config_desc_t *config_desc, uint8_t bInterfaceNumber, uint8_t bAlternateSetting, uint8_t bEndpointAddress, int *offset)

  Get an endpoint descriptor based on an endpoint's address.

  Given a configuration descriptor, get an endpoint descriptor based on it's bEndpointAddress, bAlternateSetting, and bInterfaceNumber.

  Parameters:

    - config_desc -- [in] Pointer to the start of a full configuration descriptor

    - bInterfaceNumber -- [in] Interface number

    - bAlternateSetting -- [in] Alternate setting number

    - bEndpointAddress -- [in] Endpoint address

    - offset -- [out] Byte offset of the endpoint descriptor relative to the start of the configuration descriptor. Can be NULL

  Returns:

    const usb_ep_desc_t* Pointer to endpoint descriptor, NULL if not found.

void usb_print_device_descriptor(const usb_device_desc_t *devc_desc)

  Print device descriptor.

  Parameters:

    devc_desc -- [in] Device descriptor

void usb_print_config_descriptor(const usb_config_desc_t *cfg_desc, print_class_descriptor_cb class_specific_cb)

  Print configuration descriptor.

  - This function prints the full contents of a configuration descriptor (including interface and endpoint descriptors)

  - When a non-standard descriptor is encountered, this function will call the class_specific_cb if it is provided

  Parameters:

    - cfg_desc -- [in] Configuration descriptor

    - class_specific_cb -- [in] Class specific descriptor callback. Can be NULL

void usb_print_string_descriptor(const usb_str_desc_t *str_desc)

  Print a string descriptor.

  This function will only print ASCII characters of the UTF-16 encoded string

  Parameters:

    str_desc -- [in] String descriptor

static inline int usb_round_up_to_mps(int num_bytes, int mps)

  Round up to an integer multiple of endpoint's MPS.

  This is a convenience function to round up a size/length to an endpoint's MPS (Maximum packet size). This is useful when calculating transfer or buffer lengths of IN endpoints.

  - If MPS <= 0, this function will return 0

  - If num_bytes <= 0, this function will return 0

  Parameters:

    - num_bytes -- [in] Number of bytes

    - mps -- [in] MPS

  Returns:

    int Round up integer multiple of MPS

### Type Definitions

typedef void (*print_class_descriptor_cb)(const usb_standard_desc_t*)

  Print class specific descriptor callback.

  Optional callback to be provided to usb_print_config_descriptor() function. The callback is called when when a non-standard descriptor is encountered. The callback should decode the descriptor as print it.

### Header File

- components/usb/include/usb/usb_types_stack.h

- This header file can be included with:

  >     #include "usb/usb_types_stack.h"

- This header file is a part of the API provided by the `usb` component. To declare that your component depends on `usb`, add the following to your CMakeLists.txt:

  >     REQUIRES usb

  > or

  >     PRIV_REQUIRES usb

### Structures

struct usb_parent_dev_info_t

  Parent device information.

  Public Members

  usb_device_handle_t dev_hdl

    Device's parent handle

  uint8_t port_num

    Device's parent port number

struct usb_device_info_t

  Basic information of an enumerated device.

  Public Members

  usb_parent_dev_info_t parent

    Device's parent information

  usb_speed_t speed

    Device's speed

  uint8_t dev_addr

    Device's address

  uint8_t bMaxPacketSize0

    The maximum packet size of the device's default endpoint

  uint8_t bConfigurationValue

    Device's current configuration number

  const usb_str_desc_t *str_desc_manufacturer

    Pointer to Manufacturer string descriptor (can be NULL)

  const usb_str_desc_t *str_desc_product

    Pointer to Product string descriptor (can be NULL)

  const usb_str_desc_t *str_desc_serial_num

    Pointer to Serial Number string descriptor (can be NULL)

struct usb_isoc_packet_desc_t

  Isochronous packet descriptor.

  If the number of bytes in an Isochronous transfer is larger than the MPS of the endpoint, the transfer is split into multiple packets transmitted at the endpoint's specified interval. An array of Isochronous packet descriptors describes how an Isochronous transfer should be split into multiple packets.

  Public Members

  int num_bytes

    Number of bytes to transmit/receive in the packet. IN packets should be integer multiple of MPS

  int actual_num_bytes

    Actual number of bytes transmitted/received in the packet

  usb_transfer_status_t status

    Status of the packet

struct usb_transfer_s

  USB transfer structure.

  Public Members

  uint8_t *const data_buffer

    Pointer to data buffer

  const size_t data_buffer_size

    Size of the data buffer in bytes

  int num_bytes

    Number of bytes to transfer. Control transfers should include the size of the setup packet. Isochronous transfer should be the total transfer size of all packets. For non-control IN transfers, num_bytes should be an integer multiple of MPS.

  int actual_num_bytes

    Actual number of bytes transferred

  uint32_t flags

    Transfer flags

  usb_device_handle_t device_handle

    Device handle

  uint8_t bEndpointAddress

    Endpoint Address

  usb_transfer_status_t status

    Status of the transfer

  uint32_t timeout_ms

    Timeout (in milliseconds) of the packet (currently not supported yet)

  usb_transfer_cb_t callback

    Transfer callback

  void *context

    Context variable for transfer to associate transfer with something

  const int num_isoc_packets

    Only relevant to Isochronous. Number of service periods (i.e., intervals) to transfer data buffer over.

  usb_isoc_packet_desc_t isoc_packet_desc[]

    Descriptors for each Isochronous packet

### Macros

USB_TRANSFER_FLAG_ZERO_PACK

  Terminate Bulk/Interrupt OUT transfer with a zero length packet.

  OUT transfers normally terminate when the Host has transferred the exact amount of data it needs to the device. However, for bulk and interrupt OUT transfers, if the transfer size just happened to be a multiple of MPS, it will be impossible to know the boundary between two consecutive transfers to the same endpoint.

  Therefore, this flag will cause the transfer to automatically add a zero length packet (ZLP) at the end of the transfer if the following conditions are met:

  - The target endpoint is a Bulk/Interrupt OUT endpoint (Host to device)

  - The transfer's length (i.e., transfer.num_bytes) is a multiple of the endpoint's MPS

  Otherwise, this flag has no effect.

  Users should check whether their target device's class requires a ZLP, as not all Bulk/Interrupt OUT endpoints require them. For example:

  - For MSC Bulk Only Transport class, the Host MUST NEVER send a ZLP. Bulk transfer boundaries are determined by the CBW and CSW instead

  - For CDC Ethernet, the Host MUST ALWAYS send a ZLP if a segment (i.e., a transfer) is a multiple of MPS (See 3.3.1 Segment Delineation)

  Note

  See USB2.0 specification 5.7.3 and 5.8.3 for more details

  Note

  IN transfers normally terminate when the Host as receive the exact amount of data it needs (must be multiple of MPS) or the endpoint sends a short packet to the Host (For bulk OUT only). Indicates that a bulk OUT transfers should always terminate with a short packet, even if it means adding an extra zero length packet

### Type Definitions

typedef struct usb_device_handle_s *usb_device_handle_t

  Handle of a USB Device connected to a USB Host.

typedef bool (*usb_host_enum_filter_cb_t)(const usb_device_desc_t *dev_desc, uint8_t *bConfigurationValue)

  Enumeration filter callback.

  This callback is called at the beginning of the enumeration process for a newly attached device. Through this callback, users are able to:

  - filter which devices should be enumerated

  - select the configuration number to use when enumerating the device

  The device descriptor is passed to this callback to allow users to filter devices based on Vendor ID, Product ID, and class code.

  Attention

    This callback must be non-blocking

  Attention

    This callback must not submit any USB transfers

  Param dev_desc:

    [in] Device descriptor of the device to enumerate

  Param bConfigurationValue:

    [out] Configuration number to use when enumerating the device (starts with 1)

  Return:

    bool

    - true: USB device will be enumerated

    - false: USB device will not be enumerated

typedef struct usb_transfer_s usb_transfer_t

  USB transfer structure.

  This structure is used to represent a transfer from a software client to an endpoint over the USB bus. Some of the fields are made const on purpose as they are fixed on allocation. Users should call the appropriate USB Host Library function to allocate a USB transfer structure instead of allocating this structure themselves.

  The transfer type is inferred from the endpoint this transfer is sent to. Depending on the transfer type, users should note the following:

  - Bulk: This structure represents a single bulk transfer. If the number of bytes exceeds the endpoint's MPS, the transfer will be split into multiple MPS sized packets followed by a short packet.

  - Control: This structure represents a single control transfer. This first 8 bytes of the data_buffer must be filled with the setup packet (see usb_setup_packet_t). The num_bytes field should be the total size of the transfer (i.e., size of setup packet + wLength).

  - Interrupt: Represents an interrupt transfer. If num_bytes exceeds the MPS of the endpoint, the transfer will be split into multiple packets, and each packet is transferred at the endpoint's specified interval.

  - Isochronous: Represents a stream of bytes that should be transferred to an endpoint at a fixed rate. The transfer is split into packets according to the each isoc_packet_desc. A packet is transferred at each interval of the endpoint. If an entire ISOC URB was transferred without error (skipped packets do not count as errors), the URB's overall status and the status of each packet descriptor will be updated, and the actual_num_bytes reflects the total bytes transferred over all packets. If the ISOC URB encounters an error, the entire URB is considered erroneous so only the overall status will updated.

  Note

  For Bulk/Control/Interrupt IN transfers, the num_bytes must be a integer multiple of the endpoint's MPS

  Note

  This structure should be allocated via usb_host_transfer_alloc()

  Note

  Once the transfer has be submitted, users should not modify the structure until the transfer has completed

typedef void (*usb_transfer_cb_t)(usb_transfer_t *transfer)

  USB transfer completion callback.

### Enumerations

enum usb_speed_t

  USB Standard Speeds.

  Values:

  enumerator USB_SPEED_LOW

    USB Low Speed (1.5 Mbit/s)

  enumerator USB_SPEED_FULL

    USB Full Speed (12 Mbit/s)

  enumerator USB_SPEED_HIGH

    USB High Speed (480 Mbit/s)

enum usb_transfer_type_t

  The type of USB transfer.

  Note

  The enum values need to match the bmAttributes field of an EP descriptor

  Values:

  enumerator USB_TRANSFER_TYPE_CTRL
  enumerator USB_TRANSFER_TYPE_ISOCHRONOUS
  enumerator USB_TRANSFER_TYPE_BULK
  enumerator USB_TRANSFER_TYPE_INTR

enum usb_transfer_status_t

  The status of a particular transfer.

  Values:

  enumerator USB_TRANSFER_STATUS_COMPLETED

    The transfer was successful (but may be short)

  enumerator USB_TRANSFER_STATUS_ERROR

    The transfer failed because due to excessive errors (e.g. no response or CRC error)

  enumerator USB_TRANSFER_STATUS_TIMED_OUT

    The transfer failed due to a time out

  enumerator USB_TRANSFER_STATUS_CANCELED

    The transfer was canceled

  enumerator USB_TRANSFER_STATUS_STALL

    The transfer was stalled

  enumerator USB_TRANSFER_STATUS_OVERFLOW

    The transfer as more data was sent than was requested

  enumerator USB_TRANSFER_STATUS_SKIPPED

    ISOC packets only. The packet was skipped due to system latency or bus overload

  enumerator USB_TRANSFER_STATUS_NO_DEVICE

    The transfer failed because the target device is gone

### Header File

- components/usb/include/usb/usb_types_ch9.h

- This header file can be included with:

  >     #include "usb/usb_types_ch9.h"

- This header file is a part of the API provided by the `usb` component. To declare that your component depends on `usb`, add the following to your CMakeLists.txt:

  >     REQUIRES usb

  > or

  >     PRIV_REQUIRES usb

### Unions

union usb_setup_packet_t
  #include <usb_types_ch9.h>

  Structure representing a USB control transfer setup packet.

  See Table 9-2 of USB2.0 specification for more details

  Public Members

  uint8_t bmRequestType

    Characteristics of request

  uint8_t bRequest

    Specific request

  uint16_t wValue

    Word-sized field that varies according to request

  uint16_t wIndex

    Word-sized field that varies according to request; typically used to pass an index or offset

  uint16_t wLength

    Number of bytes to transfer if there is a data stage

  struct usb_setup_packet_t USB_DESC_ATTR

    USB descriptor attributes

  uint8_t val[USB_SETUP_PACKET_SIZE]

    Descriptor value

union usb_device_status_t
  #include <usb_types_ch9.h>

  Structure representing a USB device status.

  See Figures 9-4 Information Returned by a GetStatus() Request to a Device of USB2.0 specification for more details

  Public Members

  uint16_t self_powered

    1 - Device is currently self-powered, 0 - bus powered

  uint16_t remote_wakeup

    1 - the ability of the device to signal remote wakeup is enabled, 0 - the ability of the device to signal remote wakeup is disabled.

  uint16_t reserved

    reserved

  struct usb_device_status_t USB_DESC_ATTR

    Packed

  uint16_t val

    Device status value

union usb_standard_desc_t
  #include <usb_types_ch9.h>

  USB standard descriptor.

  All USB standard descriptors start with these two bytes. Use this type when traversing over configuration descriptors

  Public Members

  uint8_t bLength

    Size of the descriptor in bytes

  uint8_t bDescriptorType

    Descriptor Type

  struct usb_standard_desc_t USB_DESC_ATTR

    USB descriptor attributes

  uint8_t val[USB_STANDARD_DESC_SIZE]

    Descriptor value

union usb_device_desc_t
  #include <usb_types_ch9.h>

  Structure representing a USB device descriptor.

  See Table 9-8 of USB2.0 specification for more details

  Public Members

  uint8_t bLength

    Size of the descriptor in bytes

  uint8_t bDescriptorType

    DEVICE Descriptor Type

  uint16_t bcdUSB

    USB Specification Release Number in Binary-Coded Decimal (i.e., 2.10 is 210H)

  uint8_t bDeviceClass

    Class code (assigned by the USB-IF)

  uint8_t bDeviceSubClass

    Subclass code (assigned by the USB-IF)

  uint8_t bDeviceProtocol

    Protocol code (assigned by the USB-IF)

  uint8_t bMaxPacketSize0

    Maximum packet size for endpoint zero (only 8, 16, 32, or 64 are valid)

  uint16_t idVendor

    Vendor ID (assigned by the USB-IF)

  uint16_t idProduct

    Product ID (assigned by the manufacturer)

  uint16_t bcdDevice

    Device release number in binary-coded decimal

  uint8_t iManufacturer

    Index of string descriptor describing manufacturer

  uint8_t iProduct

    Index of string descriptor describing product

  uint8_t iSerialNumber

    Index of string descriptor describing the device’s serial number

  uint8_t bNumConfigurations

    Number of possible configurations

  struct usb_device_desc_t USB_DESC_ATTR

    USB descriptor attributes

  uint8_t val[USB_DEVICE_DESC_SIZE]

    Descriptor value

union usb_config_desc_t
  #include <usb_types_ch9.h>

  Structure representing a short USB configuration descriptor.

  See Table 9-10 of USB2.0 specification for more details

  Note

  The full USB configuration includes all the interface and endpoint descriptors of that configuration.

  Public Members

  uint8_t bLength

    Size of the descriptor in bytes

  uint8_t bDescriptorType

    CONFIGURATION Descriptor Type

  uint16_t wTotalLength

    Total length of data returned for this configuration

  uint8_t bNumInterfaces

    Number of interfaces supported by this configuration

  uint8_t bConfigurationValue

    Value to use as an argument to the SetConfiguration() request to select this configuration

  uint8_t iConfiguration

    Index of string descriptor describing this configuration

  uint8_t bmAttributes

    Configuration characteristics

  uint8_t bMaxPower

    Maximum power consumption of the USB device from the bus in this specific configuration when the device is fully operational.

  struct usb_config_desc_t USB_DESC_ATTR

    USB descriptor attributes

  uint8_t val[USB_CONFIG_DESC_SIZE]

    Descriptor value

union usb_iad_desc_t
  #include <usb_types_ch9.h>

  Structure representing a USB interface association descriptor.

  Public Members

  uint8_t bLength

    Size of the descriptor in bytes

  uint8_t bDescriptorType

    INTERFACE ASSOCIATION Descriptor Type

  uint8_t bFirstInterface

    Interface number of the first interface that is associated with this function

  uint8_t bInterfaceCount

    Number of contiguous interfaces that are associated with this function

  uint8_t bFunctionClass

    Class code (assigned by USB-IF)

  uint8_t bFunctionSubClass

    Subclass code (assigned by USB-IF)

  uint8_t bFunctionProtocol

    Protocol code (assigned by USB-IF)

  uint8_t iFunction

    Index of string descriptor describing this function

  struct usb_iad_desc_t USB_DESC_ATTR

    USB descriptor attributes

  uint8_t val[USB_IAD_DESC_SIZE]

    Descriptor value

union usb_intf_desc_t
  #include <usb_types_ch9.h>

  Structure representing a USB interface descriptor.

  See Table 9-12 of USB2.0 specification for more details

  Public Members

  uint8_t bLength

    Size of the descriptor in bytes

  uint8_t bDescriptorType

    INTERFACE Descriptor Type

  uint8_t bInterfaceNumber

    Number of this interface.

  uint8_t bAlternateSetting

    Value used to select this alternate setting for the interface identified in the prior field

  uint8_t bNumEndpoints

    Number of endpoints used by this interface (excluding endpoint zero).

  uint8_t bInterfaceClass

    Class code (assigned by the USB-IF)

  uint8_t bInterfaceSubClass

    Subclass code (assigned by the USB-IF)

  uint8_t bInterfaceProtocol

    Protocol code (assigned by the USB)

  uint8_t iInterface

    Index of string descriptor describing this interface

  struct usb_intf_desc_t USB_DESC_ATTR

    USB descriptor attributes

  uint8_t val[USB_INTF_DESC_SIZE]

    Descriptor value

union usb_ep_desc_t
  #include <usb_types_ch9.h>

  Structure representing a USB endpoint descriptor.

  See Table 9-13 of USB2.0 specification for more details

  Public Members

  uint8_t bLength

    Size of the descriptor in bytes

  uint8_t bDescriptorType

    ENDPOINT Descriptor Type

  uint8_t bEndpointAddress

    The address of the endpoint on the USB device described by this descriptor

  uint8_t bmAttributes

    This field describes the endpoint’s attributes when it is configured using the bConfigurationValue.

  uint16_t wMaxPacketSize

    Maximum packet size this endpoint is capable of sending or receiving when this configuration is selected.

  uint8_t bInterval

    Interval for polling Isochronous and Interrupt endpoints. Expressed in frames or microframes depending on the device operating speed (1 ms for Low-Speed and Full-Speed or 125 us for USB High-Speed and above).

  struct usb_ep_desc_t USB_DESC_ATTR

    USB descriptor attributes

  uint8_t val[USB_EP_DESC_SIZE]

    Descriptor value

union usb_str_desc_t
  #include <usb_types_ch9.h>

  Structure representing a USB string descriptor.

  Public Members

  uint8_t bLength

    Size of the descriptor in bytes

  uint8_t bDescriptorType

    STRING Descriptor Type

  uint16_t wData[]

    UTF-16LE encoded

  struct usb_str_desc_t USB_DESC_ATTR

    USB descriptor attributes

  uint8_t val[USB_STR_DESC_SIZE]

    Descriptor value

### Macros

USB_DESC_ATTR

USB_B_DESCRIPTOR_TYPE_DEVICE

  Descriptor types from USB2.0 specification table 9.5.

USB_B_DESCRIPTOR_TYPE_CONFIGURATION

USB_B_DESCRIPTOR_TYPE_STRING

USB_B_DESCRIPTOR_TYPE_INTERFACE

USB_B_DESCRIPTOR_TYPE_ENDPOINT

USB_B_DESCRIPTOR_TYPE_DEVICE_QUALIFIER

USB_B_DESCRIPTOR_TYPE_OTHER_SPEED_CONFIGURATION

USB_B_DESCRIPTOR_TYPE_INTERFACE_POWER

USB_B_DESCRIPTOR_TYPE_OTG

  Descriptor types from USB 2.0 ECN.

USB_B_DESCRIPTOR_TYPE_DEBUG

USB_B_DESCRIPTOR_TYPE_INTERFACE_ASSOCIATION

USB_B_DESCRIPTOR_TYPE_SECURITY

  Descriptor types from Wireless USB spec.

USB_B_DESCRIPTOR_TYPE_KEY

USB_B_DESCRIPTOR_TYPE_ENCRYPTION_TYPE

USB_B_DESCRIPTOR_TYPE_BOS

USB_B_DESCRIPTOR_TYPE_DEVICE_CAPABILITY

USB_B_DESCRIPTOR_TYPE_WIRELESS_ENDPOINT_COMP

USB_B_DESCRIPTOR_TYPE_WIRE_ADAPTER

USB_B_DESCRIPTOR_TYPE_RPIPE

USB_B_DESCRIPTOR_TYPE_CS_RADIO_CONTROL

USB_B_DESCRIPTOR_TYPE_PIPE_USAGE

  Descriptor types from UAS specification.

USB_SETUP_PACKET_SIZE

  Size of a USB control transfer setup packet in bytes.

USB_BM_REQUEST_TYPE_DIR_OUT

  Bit masks belonging to the bmRequestType field of a setup packet.

USB_BM_REQUEST_TYPE_DIR_IN

USB_BM_REQUEST_TYPE_TYPE_STANDARD

USB_BM_REQUEST_TYPE_TYPE_CLASS

USB_BM_REQUEST_TYPE_TYPE_VENDOR

USB_BM_REQUEST_TYPE_TYPE_RESERVED

USB_BM_REQUEST_TYPE_TYPE_MASK

USB_BM_REQUEST_TYPE_RECIP_DEVICE

USB_BM_REQUEST_TYPE_RECIP_INTERFACE

USB_BM_REQUEST_TYPE_RECIP_ENDPOINT

USB_BM_REQUEST_TYPE_RECIP_OTHER

USB_BM_REQUEST_TYPE_RECIP_MASK

USB_B_REQUEST_GET_STATUS

  Bit masks belonging to the bRequest field of a setup packet.

USB_B_REQUEST_CLEAR_FEATURE

USB_B_REQUEST_SET_FEATURE

USB_B_REQUEST_SET_ADDRESS

USB_B_REQUEST_GET_DESCRIPTOR

USB_B_REQUEST_SET_DESCRIPTOR

USB_B_REQUEST_GET_CONFIGURATION

USB_B_REQUEST_SET_CONFIGURATION

USB_B_REQUEST_GET_INTERFACE

USB_B_REQUEST_SET_INTERFACE

USB_B_REQUEST_SYNCH_FRAME

USB_W_VALUE_DT_DEVICE

  Bit masks belonging to the wValue field of a setup packet.

USB_W_VALUE_DT_CONFIG

USB_W_VALUE_DT_STRING

USB_W_VALUE_DT_INTERFACE

USB_W_VALUE_DT_ENDPOINT

USB_W_VALUE_DT_DEVICE_QUALIFIER

USB_W_VALUE_DT_OTHER_SPEED_CONFIG

USB_W_VALUE_DT_INTERFACE_POWER

USB_SETUP_PACKET_INIT_GET_STATUS(setup_pkt_ptr)

  Initializer for a GET_STATUS request.

  Sets the address of a connected device

USB_SETUP_PACKET_INIT_SET_ADDR(setup_pkt_ptr, addr)

  Initializer for a SET_ADDRESS request.

  Sets the address of a connected device

USB_SETUP_PACKET_INIT_GET_DEVICE_DESC(setup_pkt_ptr)

  Initializer for a request to get a device's device descriptor.

USB_SETUP_PACKET_INIT_GET_CONFIG(setup_pkt_ptr)

  Initializer for a request to get a device's current configuration number.

USB_SETUP_PACKET_INIT_GET_CONFIG_DESC(setup_pkt_ptr, desc_index, desc_len)

  Initializer for a request to get one of the device's current configuration descriptor.

  - desc_index indicates the configuration's index number

  - Number of bytes of the configuration descriptor to get

USB_SETUP_PACKET_INIT_SET_CONFIG(setup_pkt_ptr, config_num)

  Initializer for a request to set a device's current configuration number.

USB_SETUP_PACKET_INIT_SET_INTERFACE(setup_pkt_ptr, intf_num, alt_setting_num)

  Initializer for a request to set an interface's alternate setting.

USB_SETUP_PACKET_INIT_GET_STR_DESC(setup_pkt_ptr, string_index, lang_id, desc_len)

  Initializer for a request to get an string descriptor.

USB_STANDARD_DESC_SIZE

  Size of dummy USB standard descriptor.

USB_DEVICE_DESC_SIZE

  Size of a USB device descriptor in bytes.

USB_CLASS_PER_INTERFACE

  Possible base class values of the bDeviceClass field of a USB device descriptor.

USB_CLASS_AUDIO

USB_CLASS_COMM

USB_CLASS_HID

USB_CLASS_PHYSICAL

USB_CLASS_STILL_IMAGE

USB_CLASS_PRINTER

USB_CLASS_MASS_STORAGE

USB_CLASS_HUB

USB_CLASS_CDC_DATA

USB_CLASS_CSCID

USB_CLASS_CONTENT_SEC

USB_CLASS_VIDEO

USB_CLASS_WIRELESS_CONTROLLER

USB_CLASS_PERSONAL_HEALTHCARE

USB_CLASS_AUDIO_VIDEO

USB_CLASS_BILLBOARD

USB_CLASS_USB_TYPE_C_BRIDGE

USB_CLASS_MISC

USB_CLASS_APP_SPEC

USB_CLASS_VENDOR_SPEC

USB_SUBCLASS_VENDOR_SPEC

  Vendor specific subclass code.

USB_CONFIG_DESC_SIZE

  Size of a short USB configuration descriptor in bytes.

  Note

  The size of a full USB configuration includes all the interface and endpoint descriptors of that configuration.

USB_BM_ATTRIBUTES_ONE

  Bit masks belonging to the bmAttributes field of a configuration descriptor.

  Must be set

USB_BM_ATTRIBUTES_SELFPOWER

  Self powered

USB_BM_ATTRIBUTES_WAKEUP

  Can wake-up

USB_BM_ATTRIBUTES_BATTERY

  Battery powered

USB_IAD_DESC_SIZE

  Size of a USB interface association descriptor in bytes.

USB_INTF_DESC_SIZE

  Size of a USB interface descriptor in bytes.

USB_EP_DESC_SIZE

  Size of a USB endpoint descriptor in bytes.

USB_B_ENDPOINT_ADDRESS_EP_NUM_MASK

  Bit masks belonging to the bEndpointAddress field of an endpoint descriptor.

USB_B_ENDPOINT_ADDRESS_EP_DIR_MASK

USB_W_MAX_PACKET_SIZE_MPS_MASK

  Bit masks belonging to the wMaxPacketSize field of endpoint descriptor.

USB_W_MAX_PACKET_SIZE_MULT_MASK

USB_BM_ATTRIBUTES_XFERTYPE_MASK

  Bit masks belonging to the bmAttributes field of an endpoint descriptor.

USB_BM_ATTRIBUTES_XFER_CONTROL

USB_BM_ATTRIBUTES_XFER_ISOC

USB_BM_ATTRIBUTES_XFER_BULK

USB_BM_ATTRIBUTES_XFER_INT

USB_BM_ATTRIBUTES_SYNCTYPE_MASK

USB_BM_ATTRIBUTES_SYNC_NONE

USB_BM_ATTRIBUTES_SYNC_ASYNC

USB_BM_ATTRIBUTES_SYNC_ADAPTIVE

USB_BM_ATTRIBUTES_SYNC_SYNC

USB_BM_ATTRIBUTES_USAGETYPE_MASK

USB_BM_ATTRIBUTES_USAGE_DATA

USB_BM_ATTRIBUTES_USAGE_FEEDBACK

USB_BM_ATTRIBUTES_USAGE_IMPLICIT_FB

USB_EP_DESC_GET_XFERTYPE(desc_ptr)

  Macro helpers to get information about an endpoint from its descriptor.

USB_EP_DESC_GET_EP_NUM(desc_ptr)

USB_EP_DESC_GET_EP_DIR(desc_ptr)

USB_EP_DESC_GET_MPS(desc_ptr)

USB_EP_DESC_GET_MULT(desc_ptr)

USB_EP_DESC_GET_SYNCTYPE(desc_ptr)

USB_EP_DESC_GET_USAGETYPE(desc_ptr)

USB_STR_DESC_SIZE

  Size of a short USB string descriptor in bytes.

### Enumerations

enum usb_device_state_t

  USB2.0 device states.

  See Table 9-1 of USB2.0 specification for more details

  Note

  The USB_DEVICE_STATE_NOT_ATTACHED is not part of the USB2.0 specification, but is a catch all state for devices that need to be cleaned up after a sudden disconnection or port error.

  Values:

  enumerator USB_DEVICE_STATE_NOT_ATTACHED

    The device was previously configured or suspended, but is no longer attached (either suddenly disconnected or a port error)

  enumerator USB_DEVICE_STATE_ATTACHED

    Device is attached to the USB, but is not powered.

  enumerator USB_DEVICE_STATE_POWERED

    Device is attached to the USB and powered, but has not been reset.

  enumerator USB_DEVICE_STATE_DEFAULT

    Device is attached to the USB and powered and has been reset, but has not been assigned a unique address. Device responds at the default address.

  enumerator USB_DEVICE_STATE_ADDRESS

    Device is attached to the USB, powered, has been reset, and a unique device address has been assigned. Device is not configured.

  enumerator USB_DEVICE_STATE_CONFIGURED

    Device is attached to the USB, powered, has been reset, has a unique address, is configured, and is not suspended. The host may now use the function provided by the device.

  enumerator USB_DEVICE_STATE_SUSPENDED

    Device is, at minimum, attached to the USB and is powered and has not seen bus activity for 3 ms. It may also have a unique address and be configured for use. However, because the device is suspended, the host may not use the device’s function.

## Maintainers Notes

Note

For more details regarding the internal implementation details of the USB Host stack, please refer to USB Host Maintainers Notes (Introduction).

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