#include <USBAudio.h>

Inheritance diagram for USBAudio:

Public Member Functions
	USBAudio (bool connect=true, uint32_t frequency_rx=48000, uint8_t channel_count_rx=1, uint32_t frequency_tx=8000, uint8_t channel_count_tx=1, uint32_t buffer_ms=10, uint16_t vendor_id=0x7bb8, uint16_t product_id=0x1111, uint16_t product_release=0x0100)
	Basic constructor. More...

	USBAudio (USBPhy *phy, uint32_t frequency_rx, uint8_t channel_count_rx, uint32_t frequency_tx, uint8_t channel_count_tx, uint32_t buffer_ms, uint16_t vendor_id, uint16_t product_id, uint16_t product_release)
	Fully featured constructor. More...

virtual	~USBAudio ()
	Destroy this object. More...

void	connect ()
	Connect USBAudio. More...

void	disconnect ()
	Disconnect USBAudio. More...

bool	read (uint8_t *buf, uint32_t size)
	Read audio data. More...

void	read_nb (uint8_t buf, uint32_t size, uint32_t actual)
	Nonblocking audio data read. More...

uint32_t	read_overflows (bool clear=false)
	Return the number read packets dropped due to overflow. More...

bool	read_ready ()
	Check if the audio read channel is open. More...

void	read_wait_ready ()
	Wait until the audio read channel is open. More...

bool	write (uint8_t *buf, uint32_t size)
	Write audio data. More...

void	write_nb (uint8_t buf, uint32_t size, uint32_t actual)
	Nonblocking audio data write. More...

uint32_t	write_underflows (bool clear=false)
	Return the number write packets not sent due to underflow. More...

bool	write_ready ()
	Check if the audio write channel is open. More...

void	write_wait_ready ()
	Wait until the audio write channel is open. More...

float	get_volume ()
	Get current volume between 0.0 and 1.0. More...

void	attach (mbed::Callback< void()> &cb)
	Attach a Callback to update the volume. More...

void	attach_tx (mbed::Callback< void(AudioEvent)> &cb)
	attach a Callback to Tx Done More...

void	attach_rx (mbed::Callback< void(AudioEvent)> &cb)
	attach a Callback to Rx Done More...

Protected Member Functions
virtual void	callback_state_change (DeviceState new_state)
	Called when USB changes state. More...

virtual void	callback_request (const setup_packet_t *setup)
	Called by USBDevice on Endpoint0 request. More...

virtual void	callback_request_xfer_done (const setup_packet_t *setup, bool aborted)
	Called by USBDevice on data stage completion. More...

void	init ()
	Initialize this instance. More...

void	deinit ()
	Power down this instance. More...

bool	configured ()
	Check if the device is configured. More...

void	sof_enable ()
	Enable the start of frame interrupt. More...

void	sof_disable ()
	Disable the start of frame interrupt. More...

bool	endpoint_add (usb_ep_t endpoint, uint32_t max_packet, usb_ep_type_t type, mbed::Callback< void()> callback=nullptr)
	Add an endpoint. More...

template<typename T >
bool	endpoint_add (usb_ep_t endpoint, uint32_t max_packet, usb_ep_type_t type, void(T::*callback)())
	Add an endpoint. More...

void	endpoint_remove (usb_ep_t endpoint)
	Remove an endpoint. More...

void	endpoint_remove_all ()
	Remove all non-zero endpoints. More...

void	endpoint_stall (usb_ep_t endpoint)
	Stall an endpoint. More...

void	endpoint_unstall (usb_ep_t endpoint)
	Un-stall an endpoint. More...

uint32_t	endpoint_max_packet_size (usb_ep_t endpoint)
	Get the current maximum size for this endpoint. More...

void	endpoint_abort (usb_ep_t endpoint)
	Abort the current transfer on this endpoint. More...

bool	read_start (usb_ep_t endpoint, uint8_t *buffer, uint32_t size)
	start a read on the given endpoint More...

uint32_t	read_finish (usb_ep_t endpoint)
	Get the status of a read. More...

bool	write_start (usb_ep_t endpoint, uint8_t *buffer, uint32_t size)
	Write a data to the given endpoint. More...

uint32_t	write_finish (usb_ep_t endpoint)
	Get the status of a write. More...

virtual void	callback_power (bool powered)
	Called by USBDevice layer on power state change. More...

virtual void	callback_sof (int frame_number)
	Called by USBDevice layer on each new USB frame. More...

virtual void	callback_reset ()
	Called by USBDevice layer on bus reset. More...

void	complete_request (RequestResult result, uint8_t *data=NULL, uint32_t size=0)
	Called to complete the setup stage of a callback request. More...

void	complete_request_xfer_done (bool success)
	Called to complete the data stage of a callback request. More...

void	complete_set_configuration (bool success)
	Called to complete a set configuration command. More...

void	complete_set_interface (bool success)
	Called to complete a set interface command. More...

uint8_t *	find_descriptor (uint8_t descriptor_type, uint8_t index=0)
	Find a descriptor type inside the configuration descriptor. More...

const usb_ep_table_t *	endpoint_table ()
	Get the endpoint table of this device. More...

virtual void	start_process ()
	Callback called to indicate the USB processing needs to be done. More...

virtual void	lock ()
	Acquire exclusive access to this instance USBDevice. More...

virtual void	unlock ()
	Release exclusive access to this instance USBDevice. More...

virtual void	assert_locked ()
	Assert that the current thread of execution holds the lock. More...

Detailed Description

USBAudio example.

#include "mbed.h"
#include "USBAudio.h"
 
// Audio loopback example use:
// 1. Select "Mbed Audio" as your sound device
// 2. Play a song or audio file
// 3. Record the output using a program such as Audacity
 
int main() {
 
    USBAudio audio(true, 44100, 2, 44100, 2);
 
    printf("Looping audio\r\n");
    static uint8_t buf[128];
    while (true) {
        if (!audio.read(buf, sizeof(buf))) {
            memset(buf, 0, sizeof(buf));
        }
        audio.write(buf, sizeof(buf));
    }
}

Definition at line 69 of file USBAudio.h.

Constructor & Destructor Documentation

◆ USBAudio() [1/2]

USBAudio	(	bool	connect = `true`,
		uint32_t	frequency_rx = `48000`,
		uint8_t	channel_count_rx = `1`,
		uint32_t	frequency_tx = `8000`,
		uint8_t	channel_count_tx = `1`,
		uint32_t	buffer_ms = `10`,
		uint16_t	vendor_id = `0x7bb8`,
		uint16_t	product_id = `0x1111`,
		uint16_t	product_release = `0x0100`
	)

Basic constructor.

Construct this object optionally connecting.

Note: Do not use this constructor in derived classes.

Parameters

connect	Call connect on initialization
frequency_rx	frequency in Hz (default: 48000)
channel_count_rx	channel number (1 or 2) (default: 1)
frequency_tx	frequency in Hz (default: 8000)
channel_count_tx	channel number (1 or 2) (default: 1)
buffer_ms	time audio can be buffered without overflowing in milliseconds
vendor_id	Your vendor_id
product_id	Your product_id
product_release	Your product_release

◆ USBAudio() [2/2]

USBAudio	(	USBPhy *	phy,
		uint32_t	frequency_rx,
		uint8_t	channel_count_rx,
		uint32_t	frequency_tx,
		uint8_t	channel_count_tx,
		uint32_t	buffer_ms,
		uint16_t	vendor_id,
		uint16_t	product_id,
		uint16_t	product_release
	)

Fully featured constructor.

Construct this object with the supplied USBPhy and parameters. The user this object is responsible for calling connect() or init().

Note: Derived classes must use this constructor and call init() or connect() themselves. Derived classes should also call deinit() in their destructor. This ensures that no interrupts can occur when the object is partially constructed or destroyed.

Parameters

phy	USB phy to use
frequency_rx	frequency in Hz (default: 48000)
channel_count_rx	channel number (1 or 2) (default: 1)
frequency_tx	frequency in Hz (default: 8000)
channel_count_tx	channel number (1 or 2) (default: 1)
buffer_ms	time audio can be buffered without overflowing in milliseconds
vendor_id	Your vendor_id
product_id	Your product_id
product_release	Your product_release

◆ ~USBAudio()

virtual ~USBAudio ( )

virtual

Destroy this object.

Any classes which inherit from this class must call deinit before this destructor runs.

Member Function Documentation

◆ connect()

void connect ( )

Connect USBAudio.

◆ disconnect()

void disconnect ( )

Disconnect USBAudio.

This unblocks all calls to read_ready and write_ready.

◆ read()

bool read	(	uint8_t *	buf,
		uint32_t	size
	)

Read audio data.

Parameters

buf	pointer on a buffer which will be filled with audio data
size	size to read

Returns: true if successful

◆ read_nb()

void read_nb	(	uint8_t *	buf,
		uint32_t	size,
		uint32_t *	actual
	)

Nonblocking audio data read.

Read the available audio data.

Parameters

buf	pointer on a buffer which will be filled with audio data
size	size to read
actual	size actually read

Note: This function is safe to call from USBAudio callbacks.

◆ read_overflows()

uint32_t read_overflows ( bool clear = false )

Return the number read packets dropped due to overflow.

Parameters

clear Reset the overflow count back to 0

Returns: Number of packets dropped due to overflow

◆ read_ready()

bool read_ready ( )

Check if the audio read channel is open.

Returns: true if the audio read channel open, false otherwise

◆ read_wait_ready()

void read_wait_ready ( )

Wait until the audio read channel is open.

◆ write()

bool write	(	uint8_t *	buf,
		uint32_t	size
	)

Write audio data.

Parameters

buf	pointer to audio data to write
size	size to write

Returns: true if successful

◆ write_nb()

void write_nb	(	uint8_t *	buf,
		uint32_t	size,
		uint32_t *	actual
	)

Nonblocking audio data write.

Write the available audio data.

Parameters

buf	pointer to audio data to write
size	size to write
actual	actual size written

Note: This function is safe to call from USBAudio callbacks.

◆ write_underflows()

uint32_t write_underflows ( bool clear = false )

Return the number write packets not sent due to underflow.

Parameters

clear Reset the underflow count back to 0

Returns: Number of packets that should have been sent but weren't due to overflow

◆ write_ready()

bool write_ready ( )

Check if the audio write channel is open.

Returns: true if the audio write channel open, false otherwise

◆ write_wait_ready()

void write_wait_ready ( )

Wait until the audio write channel is open.

◆ get_volume()

float get_volume ( )

Get current volume between 0.0 and 1.0.

Returns: volume

◆ attach()

void attach ( mbed::Callback< void()> & cb )

Attach a Callback to update the volume.

Parameters

cb	Callback to attach

◆ attach_tx()

void attach_tx ( mbed::Callback< void(AudioEvent)> & cb )

attach a Callback to Tx Done

Parameters

cb	Callback to attach

◆ attach_rx()

void attach_rx ( mbed::Callback< void(AudioEvent)> & cb )

attach a Callback to Rx Done

Parameters

cb	Callback to attach

◆ callback_state_change()

virtual void callback_state_change ( DeviceState new_state )

protectedvirtual

Called when USB changes state.

Parameters

new_state The new state of the USBDevice

Warning: Called in ISR context

Implements USBDevice.

◆ callback_request()

virtual void callback_request ( const setup_packet_t * setup )

protectedvirtual

Called by USBDevice on Endpoint0 request.

This is used to handle extensions to standard requests and class specific requests. The function complete_request must be always be called in response to this callback.

Warning: Called in ISR context

Implements USBDevice.

◆ callback_request_xfer_done()

virtual void callback_request_xfer_done	(	const setup_packet_t *	setup,
		bool	aborted
	)

protectedvirtual

Called by USBDevice on data stage completion.

The function complete_request_xfer_done must be always be called in response to this callback.

Parameters

setup	Setup packet of the current request
aborted	false if the operation was aborted, true otherwise

Warning: Called in ISR context

Implements USBDevice.

◆ init()

void init ( )

inherited

Initialize this instance.

This function must be called before calling any other functions of this class, unless specifically

◆ deinit()

void deinit ( )

inherited

Power down this instance.

Disable interrupts and stop sending events. This method can be used for temporary power-saving; This call can allow USB to be temporarily disabled to permit power saving. However, it is up to the user to make sure all the transfers have concluded (for example when USB power is lost). USBDevice::connect can be used to resume USB operation.

◆ configured()

bool configured ( )

inherited

Check if the device is configured.

Returns: true if configured, false otherwise

◆ sof_enable()

void sof_enable ( )

inherited

Enable the start of frame interrupt.

Call USBDevice::callback_sof on every frame.

◆ sof_disable()

void sof_disable ( )

inherited

Disable the start of frame interrupt.

Stop calling USBDevice::callback_sof.

◆ endpoint_add() [1/2]

bool endpoint_add	(	usb_ep_t	endpoint,
		uint32_t	max_packet,
		usb_ep_type_t	type,
		mbed::Callback< void()>	callback = `nullptr`
	)

inherited

Add an endpoint.

Parameters

endpoint	Endpoint to enable
max_packet	Maximum size of a packet which can be sent or received on this endpoint
type	Endpoint type - USB_EP_TYPE_BULK, USB_EP_TYPE_INT or USB_EP_TYPE_ISO
callback	Method pointer to be called when a packet is transferred

Returns: true if successful, false otherwise

◆ endpoint_add() [2/2]

bool endpoint_add	(	usb_ep_t	endpoint,
		uint32_t	max_packet,
		usb_ep_type_t	type,
		void(T::*)()	callback
	)

inherited

Add an endpoint.

Parameters

endpoint	Endpoint to enable
max_packet	Maximum size of a packet which can be sent or received on this endpoint
type	Endpoint type - USB_EP_TYPE_BULK, USB_EP_TYPE_INT or USB_EP_TYPE_ISO
callback	Method pointer to be called when a packet is transferred

Returns: true if successful, false otherwise

Definition at line 162 of file USBDevice.h.

◆ endpoint_remove()

void endpoint_remove ( usb_ep_t endpoint )

inherited

Remove an endpoint.

Parameters

endpoint Endpoint to disable

Note: This endpoint must already have been setup with endpoint_add

◆ endpoint_remove_all()

void endpoint_remove_all ( )

inherited

Remove all non-zero endpoints.

◆ endpoint_stall()

void endpoint_stall ( usb_ep_t endpoint )

inherited

Stall an endpoint.

If there is an ongoing transfer on this endpoint then it will be aborted.

Parameters

endpoint Endpoint to stall

Note: You cannot stall endpoint 0 with this function; This endpoint must already have been setup with endpoint_add

◆ endpoint_unstall()

void endpoint_unstall ( usb_ep_t endpoint )

inherited

Un-stall an endpoint.

Un-stalling an endpoint resets data toggle back to DATA0. Additionally, if there is an ongoing transfer on this endpoint it will be aborted.

Parameters

endpoint Endpoint to un-stall

Note: This endpoint must already have been setup with endpoint_add

◆ endpoint_max_packet_size()

uint32_t endpoint_max_packet_size ( usb_ep_t endpoint )

inherited

Get the current maximum size for this endpoint.

Return the currently configured maximum packet size, wMaxPacketSize, for this endpoint.

Note: This endpoint must already have been setup with endpoint_add

◆ endpoint_abort()

void endpoint_abort ( usb_ep_t endpoint )

inherited

Abort the current transfer on this endpoint.

Parameters

endpoint endpoint with transfer to abort

Note: This endpoint must already have been setup with endpoint_add

◆ read_start()

bool read_start	(	usb_ep_t	endpoint,
		uint8_t *	buffer,
		uint32_t	size
	)

inherited

start a read on the given endpoint

Start a read on the given endpoint. The data buffer must remain unchanged until the transfer either completes or is aborted.

Parameters

endpoint	endpoint to read data from
buffer	buffer to fill with read data
size	The size of data to read. This must be greater than or equal to the max packet size for this endpoint

Returns: true if the read was completed, otherwise false

Note: This endpoint must already have been setup with endpoint_add

◆ read_finish()

uint32_t read_finish ( usb_ep_t endpoint )

inherited

Get the status of a read.

Parameters

endpoint endpoint to get the status of

Returns: number of bytes read by this endpoint

◆ write_start()

bool write_start	(	usb_ep_t	endpoint,
		uint8_t *	buffer,
		uint32_t	size
	)

inherited

Write a data to the given endpoint.

Write data to an endpoint. The data sent must remain unchanged until the transfer either completes or is aborted.

Parameters

endpoint	endpoint to write data to
buffer	data to write
size	the size of data to send. This must be less than or equal to the max packet size of this endpoint

Note: This endpoint must already have been setup with endpoint_add

◆ write_finish()

uint32_t write_finish ( usb_ep_t endpoint )

inherited

Get the status of a write.

Parameters

endpoint endpoint to get the status of

Returns: number of bytes sent by this endpoint

◆ callback_power()

virtual void callback_power ( bool powered )

protectedvirtualinherited

Called by USBDevice layer on power state change.

Parameters

powered true if device is powered, false otherwise

Warning: Called in ISR context

Definition at line 342 of file USBDevice.h.

◆ callback_sof()

virtual void callback_sof ( int frame_number )

protectedvirtualinherited

Called by USBDevice layer on each new USB frame.

Callbacks are enabled and disabled by calling sof_enable and sof_disable.

Parameters

frame_number The current frame number

Warning: Called in ISR context

Definition at line 357 of file USBDevice.h.

◆ callback_reset()

virtual void callback_reset ( )

protectedvirtualinherited

Called by USBDevice layer on bus reset.

complete_reset must be called after the device is fully reset.

Warning: Called in ISR context

Reimplemented in USBCDC_ECM, and USBCDC.

Definition at line 370 of file USBDevice.h.

◆ complete_request()

void complete_request	(	RequestResult	result,
		uint8_t *	data = `NULL`,
		uint32_t	size = `0`
	)

protectedinherited

Called to complete the setup stage of a callback request.

Possible options that can be passed as a result are:

Receive - Start the data OUT phase of this control transfer
Send - Start the data IN phase of this control transfer
Success - Operation was a success so start the status phase
Failure - Operation failed or is unsupported so send a stall
PassThrough - Pass on the request for standard processing

Parameters

result	The result of the setup phase.
data	Buffer to send or receive if the result is Send or Receive
size	Size to transfer if the result is Send or Receive

◆ complete_request_xfer_done()

void complete_request_xfer_done ( bool success )

protectedinherited

Called to complete the data stage of a callback request.

Parameters

success true if the operation was successful, false otherwise

◆ complete_set_configuration()

void complete_set_configuration ( bool success )

protectedinherited

Called to complete a set configuration command.

Parameters

success true if the configuration was set, false otherwise

◆ complete_set_interface()

void complete_set_interface ( bool success )

protectedinherited

Called to complete a set interface command.

Parameters

success true if the interface was set, false otherwise

◆ find_descriptor()

uint8_t * find_descriptor	(	uint8_t	descriptor_type,
		uint8_t	index = `0`
	)

protectedinherited

Find a descriptor type inside the configuration descriptor.

Parameters

descriptor_type	Type of descriptor to find
index	Configuration descriptor index ( 0 if only one configuration present )

Returns: A descriptor of the given type or NULL if none were found

◆ endpoint_table()

const usb_ep_table_t * endpoint_table ( )

protectedinherited

Get the endpoint table of this device.

Returns: Endpoint table of the USBPhy attached to this USBDevice

◆ start_process()

virtual void start_process ( )

protectedvirtualinherited

Callback called to indicate the USB processing needs to be done.

Implements USBPhyEvents.

◆ lock()

virtual void lock ( )

protectedvirtualinherited

Acquire exclusive access to this instance USBDevice.

◆ unlock()

virtual void unlock ( )

protectedvirtualinherited

Release exclusive access to this instance USBDevice.

◆ assert_locked()

virtual void assert_locked ( )

protectedvirtualinherited

Assert that the current thread of execution holds the lock.

Public Member Functions

Protected Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ USBAudio() [1/2]

◆ USBAudio() [2/2]

◆ ~USBAudio()

Member Function Documentation

◆ connect()

◆ disconnect()

◆ read()

◆ read_nb()

◆ read_overflows()

◆ read_ready()

◆ read_wait_ready()

◆ write()

◆ write_nb()

◆ write_underflows()

◆ write_ready()

◆ write_wait_ready()

◆ get_volume()

◆ attach()

◆ attach_tx()

◆ attach_rx()

◆ callback_state_change()

◆ callback_request()

◆ callback_request_xfer_done()

◆ init()

◆ deinit()

◆ configured()

◆ sof_enable()

◆ sof_disable()

◆ endpoint_add() [1/2]

◆ endpoint_add() [2/2]

◆ endpoint_remove()

◆ endpoint_remove_all()

◆ endpoint_stall()

◆ endpoint_unstall()

◆ endpoint_max_packet_size()

◆ endpoint_abort()

◆ read_start()

◆ read_finish()

◆ write_start()

◆ write_finish()

◆ callback_power()

◆ callback_sof()

◆ callback_reset()

◆ complete_request()

◆ complete_request_xfer_done()

◆ complete_set_configuration()

◆ complete_set_interface()

◆ find_descriptor()

◆ endpoint_table()

◆ start_process()

◆ lock()

◆ unlock()

◆ assert_locked()