USBAudioHostBackendESP32 Class Reference

USBAudioHostBackend for the ESP-IDF usb_host library which is part of arduino-esp32 (ESP32-S2, ESP32-S3 and ESP32-P4). More...

#include <USBAudioHostBackendESP32.h>

Inheritance diagram for USBAudioHostBackendESP32:

Classes
struct	Interface
struct	Stream

Public Member Functions
	~USBAudioHostBackendESP32 ()
bool	begin (USBAudioHostEvents *events, const USBAudioConfig &cfg) override
	Start the host stack and register the event receiver.
void	closeStream (uint8_t daddr, uint8_t ep_addr) override
	Stop streaming the indicated endpoint.
bool	control (uint8_t daddr, const UsbSetupPacket &setup, uint8_t *data) override
void	end () override
	Stop all streams (the host stack itself keeps running).
uint32_t	millis () const override
	Milliseconds since start (for control request timeouts).
bool	openStream (uint8_t daddr, const UsbEndpointDescriptorView &ep, UsbHostStreamRole role) override
bool	setInterface (uint8_t daddr, uint8_t itf, uint8_t alt) override
UsbSpeed	speed () const override
	Bus speed of the attached device.
void	task () override
	Pump the host stack on platforms where the application drives it.

Static Public Attributes
static constexpr int	kPacketsPerTransfer = 4
	Number of isochronous packets (1 ms at full speed) per transfer.
static constexpr int	kTransfersInFlight = 2
	Number of transfers which are kept in flight per endpoint.

Protected Member Functions
void	closeDevice ()
Interface *	findInterface (uint8_t itf)
Stream *	findStream (uint8_t ep_addr)
Stream *	findStream (usb_transfer_t *xfer)
void	freeTransfers (Stream &s)
void	openDevice (uint8_t address)
bool	releaseInterface (Interface &itf)
void	submit (Stream &s, usb_transfer_t *xfer)

Static Protected Member Functions
static void	clientEvent (const usb_host_client_event_msg_t *msg, void *arg)
static void	controlComplete (usb_transfer_t *xfer)
static bool	installLibrary ()
static void	isoComplete (usb_transfer_t *xfer)
static void	libraryTask (void *)

Protected Attributes
usb_host_client_handle_t	client_ = nullptr
uint8_t *	ctrl_data_ = nullptr
uint16_t	ctrl_len_ = 0
usb_transfer_t *	ctrl_xfer_ = nullptr
uint8_t	daddr_ = 0
usb_device_handle_t	dev_ = nullptr
USBAudioHostEvents *	events_ = nullptr
std::vector< Interface >	interfaces_
std::vector< Stream >	streams_

Static Protected Attributes
static constexpr size_t	kCtrlXferSize = 8 + 512
static bool	s_library_installed_ = false
static TaskHandle_t	s_library_task_ = nullptr

Detailed Description

USBAudioHostBackend for the ESP-IDF usb_host library which is part of arduino-esp32 (ESP32-S2, ESP32-S3 and ESP32-P4).

begin() installs the USB host library (unless it was already installed, e.g. by another library) and starts a task which processes the library events. The client events and transfer completions are processed by task(), which is called continuously by the USB task of USBAudioHostESP32.

Isochronous endpoints are streamed with two transfers in flight, each covering kPacketsPerTransfer service intervals.

Author

Phil Schatzmann

Copyright

GPLv3

Constructor & Destructor Documentation

~USBAudioHostBackendESP32()

~USBAudioHostBackendESP32 ( )

inline

Member Function Documentation

begin()

bool begin ( USBAudioHostEvents *  events, const USBAudioConfig &  cfg  )

inlineoverridevirtual

Start the host stack and register the event receiver.

Implements USBAudioHostBackend.

clientEvent()

static void clientEvent ( const usb_host_client_event_msg_t *  msg, void *  arg  )

inlinestaticprotected

closeDevice()

void closeDevice ( )

inlineprotected

closeStream()

void closeStream ( uint8_t  daddr, uint8_t  ep_addr  )

inlineoverridevirtual

Stop streaming the indicated endpoint.

Implements USBAudioHostBackend.

control()

bool control ( uint8_t  daddr, const UsbSetupPacket &  setup, uint8_t *  data  )

inlineoverridevirtual

Asynchronous control request on EP0. For IN requests data receives up to setup.wLength bytes; for OUT requests it holds the payload. data must stay valid until onControlComplete().

Implements USBAudioHostBackend.

controlComplete()

static void controlComplete ( usb_transfer_t *  xfer )

inlinestaticprotected

end()

void end ( )

inlineoverridevirtual

Stop all streams (the host stack itself keeps running).

Implements USBAudioHostBackend.

findInterface()

Interface * findInterface ( uint8_t  itf )

inlineprotected

findStream() [1/2]

Stream * findStream ( uint8_t  ep_addr )

inlineprotected

findStream() [2/2]

Stream * findStream ( usb_transfer_t *  xfer )

inlineprotected

freeTransfers()

void freeTransfers ( Stream &  s )

inlineprotected

installLibrary()

static bool installLibrary ( )

inlinestaticprotected

Installs the USB host library and starts the task which handles its events

isoComplete()

static void isoComplete ( usb_transfer_t *  xfer )

inlinestaticprotected

libraryTask()

static void libraryTask ( void *  )

inlinestaticprotected

millis()

uint32_t millis ( ) const

inlineoverridevirtual

Milliseconds since start (for control request timeouts).

Implements USBAudioHostBackend.

openDevice()

void openDevice ( uint8_t  address )

inlineprotected

Opens a newly enumerated device and provides its audio control interface to the class logic

openStream()

bool openStream ( uint8_t  daddr, const UsbEndpointDescriptorView &  ep, UsbHostStreamRole  role  )

inlineoverridevirtual

Open an isochronous endpoint of the currently selected alternate setting and start streaming it in the indicated role.

Implements USBAudioHostBackend.

releaseInterface()

bool releaseInterface ( Interface &  itf )

inlineprotected

Releasing an interface requires that its endpoints are idle: when transfers are still being returned this fails and setInterface() is retried by the class logic.

setInterface()

bool setInterface ( uint8_t  daddr, uint8_t  itf, uint8_t  alt  )

inlineoverridevirtual

Claims the interface with the alternate setting (which allocates its endpoints) and sends SET_INTERFACE.

Implements USBAudioHostBackend.

speed()

UsbSpeed speed ( ) const

inlineoverridevirtual

Bus speed of the attached device.

Reimplemented from USBAudioHostBackend.

submit()

void submit ( Stream &  s, usb_transfer_t *  xfer  )

inlineprotected

task()

void task ( )

inlineoverridevirtual

Pump the host stack on platforms where the application drives it.

Implements USBAudioHostBackend.

Member Data Documentation

client_

usb_host_client_handle_t client_ = nullptr

protected

ctrl_data_

uint8_t* ctrl_data_ = nullptr

protected

ctrl_len_

uint16_t ctrl_len_ = 0

protected

ctrl_xfer_

usb_transfer_t* ctrl_xfer_ = nullptr

protected

daddr_

uint8_t daddr_ = 0

protected

dev_

usb_device_handle_t dev_ = nullptr

protected

events_

USBAudioHostEvents* events_ = nullptr

protected

interfaces_

std::vector<Interface> interfaces_

protected

kCtrlXferSize

constexpr size_t kCtrlXferSize = 8 + 512

staticconstexprprotected

kPacketsPerTransfer

constexpr int kPacketsPerTransfer = 4

staticconstexpr

Number of isochronous packets (1 ms at full speed) per transfer.

kTransfersInFlight

constexpr int kTransfersInFlight = 2

staticconstexpr

Number of transfers which are kept in flight per endpoint.

s_library_installed_

bool s_library_installed_ = false

inlinestaticprotected

s_library_task_

TaskHandle_t s_library_task_ = nullptr

inlinestaticprotected

streams_

std::vector<Stream> streams_

protected

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The documentation for this class was generated from the following file:

• src/AudioTools/Communication/USB/USBAudioHostBackendESP32.h