ESP32PDMAudio Class Reference

PDM object with IRQ-based callbacks to a FreeRTOS task, for use with BackgroundAudio. More...

#include <ESP32PDMAudio.h>

Inheritance diagram for ESP32PDMAudio:

Collaboration diagram for ESP32PDMAudio:

Public Member Functions
	ESP32PDMAudio (int8_t dout=0)
	Construct ESP32-based PDM object with IRQ-based callbacks to a FreeRTOS task, for use with BackgroundAudio.
void	setPin (int8_t dout)
	Set the PDM GPIO pin before calling begin
bool	setFrequency (int freq) override
	Set the sample rate of the PDM interface. Can be called while running.
bool	begin () override
	Start the PDM interface.
Public Member Functions inherited from ESP32I2SAudio
	ESP32I2SAudio (int8_t bclk=0, int8_t ws=1, int8_t dout=2, int8_t mclk=-1)
	Construct ESP32-based I2S object with IRQ-based callbacks to a FreeRTOS task, for use with BackgroundAudio.
void	setPins (int8_t bclk, int8_t ws, int8_t dout, int8_t mclk=-1)
	Set the I2S GPIO pins before calling begin
void	setInverted (bool bclk, bool ws, bool mclk=false)
	Set the I2S GPIO inversions before calling begin
bool	setBuffers (size_t buffers, size_t bufferWords, int32_t silenceSample=0) override
	Set the size and number of the I2S buffers before begin
bool	setBitsPerSample (int bps) override
	Set the bits per sample for the I2S output. Only 16-bit supported.
bool	setFrequency (int freq) override
	Set the sample rate (LRCLK/WS) of the I2S interface. Can be called while running.
bool	setStereo (bool stereo=true) override
	Set mono or stereo mode. Only stereo supported.
bool	begin () override
	Start the I2S interface.
void	_backgroundTask ()
	Background I2S DMA buffer notification task. Tracks number of bytes available to be written.
void	_saturating_add_available (uint32_t add)
void	_saturating_sub_available (uint32_t sub)
uint32_t	frames ()
	Get number of DMA frames(buffers) processed.
uint32_t	irqs ()
	Get the number of input data shifts processed by decoder since begin
uint32_t	underflows ()
	Get the number of times the MP3 decoder has underflowed waiting on raw data since begin
IRAM_ATTR bool	_onSentCB (i2s_chan_handle_t handle, i2s_event_data_t *event)
	Object-based callback for I2S Sent notification.
bool	end () override
	Stop the I2S device.
bool	getUnderflow () override
	Determine if there was an underflow since the last time this was called. Cleared on read.
void	onTransmit (void(*cb)(void *), void *cbData) override
	Set the callback function to be called every DMA buffer completion.
size_t	write (const uint8_t *buffer, size_t size) override
	Write data to the I2S interface. Not legal from IRQ context. Will not block and may write less than requested.
size_t	write (uint8_t d) override
	Write single byte to I2S buffers. Not supported.
int	availableForWrite () override
	Determine the number of frames we can write to the DMA buffers at this instant.

Additional Inherited Members
Static Public Member Functions inherited from ESP32I2SAudio
static IRAM_ATTR bool	_onSent (i2s_chan_handle_t handle, i2s_event_data_t *event, void *user_ctx)
	C-language wrapper for I2S Sent event.
static void	_taskShim (void *pvParameters)
	C-language shim to start the real object's task.
Protected Attributes inherited from ESP32I2SAudio
bool	_running
int8_t	_bclk = 0
int8_t	_ws = 1
int8_t	_dout = 2
int8_t	_mclk = -1
bool	_bclkInv = false
bool	_wsInv = false
bool	_mclkInv = false
std::atomic< bool >	_underflowed {false}
size_t	_sampleRate
size_t	_buffers
size_t	_bufferWords
uint32_t	_silenceSample
TaskHandle_t	_taskHandle = 0
void(*	_cb )(void *)
void *	_cbData
i2s_chan_handle_t	_tx_handle
size_t	_totalAvailable = 0
std::atomic< uint32_t >	_available {0}
uint32_t	_irqs = 0
uint32_t	_frames = 0
std::atomic< uint32_t >	_underflows {0}

Detailed Description

PDM object with IRQ-based callbacks to a FreeRTOS task, for use with BackgroundAudio.

Constructor & Destructor Documentation

ESP32PDMAudio()

ESP32PDMAudio::ESP32PDMAudio ( int8_t  dout = 0 )

inline

Construct ESP32-based PDM object with IRQ-based callbacks to a FreeRTOS task, for use with BackgroundAudio.

Parameters

[in]

dout

GPIO pin to use as the DOUT from the PDM device

Member Function Documentation

begin()

bool ESP32PDMAudio::begin ( )

inlineoverride

Start the PDM interface.

Allocates an I2S hardware device with the requested number and size of DMA buffers and pinout. A FreeRTOS task is started, awoken from the I2S DMA buffer complete interrupt, to process the reading and writing and keep track of the available sample space for upper layers.

Returns

True on success

setFrequency()

bool ESP32PDMAudio::setFrequency ( int  freq )

inlineoverride

Set the sample rate of the PDM interface. Can be called while running.

Parameters

[in]

freq

New sampling frequency in hertz

Returns

True if succeeded

setPin()

void ESP32PDMAudio::setPin ( int8_t  dout )

inline

Set the PDM GPIO pin before calling begin

Parameters

[in]

dout

GPIO pin to use as the PDM output (connected to the LPF and speaker/amp)

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

• ESP32PDMAudio.h