Abstract seam for every raw USB-stack call the UAC2 driver (USBAudioDeviceBase) needs. Concrete subclasses wrap TinyUSB (USBAudioBackendTinyUSB, today) or a native peripheral driver (STM32 HAL / Renesas USBFS — future work). More...

#include <USBAudioBackend.h>

Inheritance diagram for USBAudioBackend:

Public Member Functions
virtual	~USBAudioBackend ()=default

virtual bool	claimEndpoint (uint8_t rhport, uint8_t ep_addr)=0

virtual bool	clearStall (uint8_t rhport, uint8_t ep_addr)=0
	Clear a halted/stalled condition on an endpoint.

virtual bool	closeEndpoint (uint8_t rhport, uint8_t ep_addr)=0

virtual bool	controlStatus (uint8_t rhport, const UsbSetupPacket &request)=0
	Send a zero-length-packet status acknowledgement.

virtual bool	controlTransfer (uint8_t rhport, const UsbSetupPacket &request, uint8_t *buffer, uint16_t length)=0
	Complete a GET/SET control transfer's data stage with `buffer`.

virtual void	enableSof (uint8_t rhport, bool enable)=0

bool	isFullSpeed () const
	Convenience: speed() == UsbSpeed::Full.

bool	isHighSpeed () const
	Convenience: speed() == UsbSpeed::High.

virtual bool	isoActivateEndpoint (uint8_t rhport, const UsbEndpointDescriptorView &ep)=0

virtual bool	isoAllocEndpoint (uint8_t rhport, uint8_t ep_addr, uint16_t max_packet_size)=0

virtual bool	mounted () const =0
	True once the device has completed USB enumeration.

virtual bool	openEndpoint (uint8_t rhport, const UsbEndpointDescriptorView &ep)=0

virtual bool	releaseEndpoint (uint8_t rhport, uint8_t ep_addr)=0

virtual UsbSpeed	speed () const =0
	Current negotiated bus speed.

virtual bool	transfer (uint8_t rhport, uint8_t ep_addr, uint8_t *buffer, uint16_t length)=0

virtual bool	usesIsoAlloc () const =0

Detailed Description

Abstract seam for every raw USB-stack call the UAC2 driver (USBAudioDeviceBase) needs. Concrete subclasses wrap TinyUSB (USBAudioBackendTinyUSB, today) or a native peripheral driver (STM32 HAL / Renesas USBFS — future work).

Only linear-buffer transfers are supported — there is no FIFO-mode transfer API.

Author: Phil Schatzmann

Copyright: GPLv3

Constructor & Destructor Documentation

◆ ~USBAudioBackend()

virtual ~USBAudioBackend ( )

virtualdefault

Member Function Documentation

◆ claimEndpoint()

virtual bool claimEndpoint	(	uint8_t	rhport,
		uint8_t	ep_addr
	)

pure virtual

True if the endpoint is currently free to accept a new transfer (used to gate feedback sends from the SOF ISR).

Implemented in USBAudioBackendTinyUSB.

◆ clearStall()

virtual bool clearStall	(	uint8_t	rhport,
		uint8_t	ep_addr
	)

pure virtual

Clear a halted/stalled condition on an endpoint.

Implemented in USBAudioBackendTinyUSB.

◆ closeEndpoint()

virtual bool closeEndpoint	(	uint8_t	rhport,
		uint8_t	ep_addr
	)

pure virtual

Close a previously opened endpoint. Only called when usesIsoAlloc() is false (backends using iso-alloc keep the endpoint reserved and just re-activate it on the next alt-setting).

Implemented in USBAudioBackendTinyUSB.

◆ controlStatus()

virtual bool controlStatus	(	uint8_t	rhport,
		const UsbSetupPacket &	request
	)

pure virtual

Send a zero-length-packet status acknowledgement.

Implemented in USBAudioBackendTinyUSB.

◆ controlTransfer()

virtual bool controlTransfer	(	uint8_t	rhport,
		const UsbSetupPacket &	request,
		uint8_t *	buffer,
		uint16_t	length
	)

pure virtual

Complete a GET/SET control transfer's data stage with buffer.

Implemented in USBAudioBackendTinyUSB.

◆ enableSof()

virtual void enableSof	(	uint8_t	rhport,
		bool	enable
	)

pure virtual

Enable/disable the start-of-frame interrupt for the audio feedback consumer. Backends without a SOF concept (e.g. one that polls instead) may implement this as a no-op, but must then drive the feedback-interval logic themselves — not a concern for the TinyUSB backend.

Implemented in USBAudioBackendTinyUSB.

◆ isFullSpeed()

bool isFullSpeed ( ) const

inline

Convenience: speed() == UsbSpeed::Full.

◆ isHighSpeed()

bool isHighSpeed ( ) const

inline

Convenience: speed() == UsbSpeed::High.

◆ isoActivateEndpoint()

virtual bool isoActivateEndpoint	(	uint8_t	rhport,
		const UsbEndpointDescriptorView &	ep
	)

pure virtual

Activate a previously iso-allocated endpoint for the given descriptor (arms it to accept traffic at the given alt setting's packet size).

Implemented in USBAudioBackendTinyUSB.

◆ isoAllocEndpoint()

virtual bool isoAllocEndpoint	(	uint8_t	rhport,
		uint8_t	ep_addr,
		uint16_t	max_packet_size
	)

pure virtual

Reserve buffer space for an isochronous endpoint. Only called when usesIsoAlloc() is true. Safe to call once per endpoint lifetime.

Implemented in USBAudioBackendTinyUSB.

◆ mounted()

virtual bool mounted ( ) const

pure virtual

True once the device has completed USB enumeration.

Implemented in USBAudioBackendTinyUSB.

◆ openEndpoint()

virtual bool openEndpoint	(	uint8_t	rhport,
		const UsbEndpointDescriptorView &	ep
	)

pure virtual

Open a non-isochronous endpoint (used for the AC interrupt EP, and for data endpoints on backends where usesIsoAlloc() is false).

Implemented in USBAudioBackendTinyUSB.

◆ releaseEndpoint()

virtual bool releaseEndpoint	(	uint8_t	rhport,
		uint8_t	ep_addr
	)

pure virtual

Release the busy/claim flag on an iso endpoint without closing it (used right after a pre-activation during enumeration so a later transfer can arm normally).

Implemented in USBAudioBackendTinyUSB.

◆ speed()

virtual UsbSpeed speed ( ) const

pure virtual

Current negotiated bus speed.

Implemented in USBAudioBackendTinyUSB.

◆ transfer()

virtual bool transfer	(	uint8_t	rhport,
		uint8_t	ep_addr,
		uint8_t *	buffer,
		uint16_t	length
	)

pure virtual

Arm one linear-buffer IN or OUT transfer. buffer must stay valid until the transfer-complete callback fires. Returns false if the endpoint could not be armed (already busy, not open, etc).

Implemented in USBAudioBackendTinyUSB.

◆ usesIsoAlloc()

virtual bool usesIsoAlloc ( ) const

pure virtual

True if this backend must pre-allocate iso endpoint buffer space once (in audiod_open) and only (re)activate it on each SET_INTERFACE, rather than open/close per alt-setting (mirrors TinyUSB's TUP_DCD_EDPT_ISO_ALLOC platform capability). Lets the UAC2 driver pick one code path at runtime instead of branching on a preprocessor macro.

Implemented in USBAudioBackendTinyUSB.

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

src/AudioTools/Communication/USB/USBAudioBackend.h

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ ~USBAudioBackend()

Member Function Documentation

◆ claimEndpoint()

◆ clearStall()

◆ closeEndpoint()

◆ controlStatus()

◆ controlTransfer()

◆ enableSof()

◆ isFullSpeed()

◆ isHighSpeed()

◆ isoActivateEndpoint()

◆ isoAllocEndpoint()

◆ mounted()

◆ openEndpoint()

◆ releaseEndpoint()

◆ speed()

◆ transfer()

◆ usesIsoAlloc()