Class AudioCodec

Description

A class used for general control and management of the hardware audio codec functions.

Syntax

class AudioCodec

Members

Public Constructors

The public constructor should not be used as this class is intended to be a singleton class. Access member functions using the object instance named Codec.

Public Methods

AudioCodec::begin

Configure and start the audio codec for transmit and receive operation

AudioCodec::end

Stop all audio codec operation

AudioCodec::getBufferPageSize

Get the byte size of a single page of the audio codec buffer

AudioCodec::setSampleRate

Configure the audio codec transmit and receive sampling rate

AudioCodec::setBitDepth

Configure the audio codec transmit and receive bit depth (bits per sample)

AudioCodec::setChannelCount

Configure the audio codec transmit and receive channel count

AudioCodec::setInputMicType

Configure for analog or digital input microphone type

AudioCodec::setInputLRMux

Configure input left right channel multiplexing

AudioCodec::setDMicBoost

Configure boost gain for digital microphone input

AudioCodec::setAMicBoost

Configure boost gain for analog microphone input

AudioCodec::setADCGain

Configure gain of ADC used to acquire analog input

AudioCodec::muteInput

Mute input audio data stream

AudioCodec::setOutputVolume

Configure output audio volume

AudioCodec::muteOutput

Mute output audio

AudioCodec::writeAvaliable

Check for free buffer page available for data write

AudioCodec::writeDataPage

Write audio data to an available buffer page

AudioCodec::readAvaliable

Check for buffer page with new data available for read

AudioCodec::readDataPage

Read audio data from a ready buffer page

AudioCodec::setWriteCallback

Set a callback function to be notified when a free buffer page is available for write

AudioCodec::setReadCallback

Set a callback function to be notified when a buffer page with new data is available for read
AudioCodec::begin

Description

Configure and start the audio codec for transmit and receive operation.

Syntax

void begin(bool input, bool output);

Parameters

input : enable audio codec data input

output: enable audio codec data output

Returns

The function returns nothing.

Example Code

Example: BasicInputOutput

Notes and Warnings

NA

AudioCodec::end

Description

Stop all audio codec operation.

Syntax

void end();

Parameters

The function requires no input parameter.

Returns

The function returns nothing.

Example Code

NA

Notes and Warnings

NA

AudioCodec::getBufferPageSize

Description

Get the byte size of a single page of the audio codec buffer.

Syntax

uint32_t getBufferPageSize();

Parameters

The function requires no input parameter.

Returns

The size of a audio codec buffer page, in number of bytes.

Example Code

NA

Notes and Warnings

The AudioCodec class includes a transmit and receive buffer to store audio sample data while transferring to and from the DAC output and ADC input. The buffer is divided into pages of fixed size, and audio data can be read and written one page at a time. Depending on the configured bit depth (bits per audio sample) and channel count, a buffer page may contain a different number of audio samples.

AudioCodec::setSampleRate

Description

Configure the audio codec transmit and receive sampling rate.

Syntax

void setSampleRate(uint32_t sampleRate);

Parameters

sampleRate : desired audio codec sampling rate in Hz. Default value of 1. Supported values: 8000, 16000, 32000, 44100, 48000, 88200, 96000.

Returns

The function returns nothing.

Example Code

Example: BasicInputOutput

Notes and Warnings

High sample rates above 48000Hz will require frequent buffer reads and writes to keep up with the large amount of data input and output. If there is insufficient processing time dedicated to this task, audio quality will be degraded.

AudioCodec::setBitDepth

Description

Configure the audio codec transmit and receive bit depth (bits per sample).

Syntax

void setBitDepth(uint8_t bitDepth);

Parameters

bitDepth : desired number of bits per sample. Default value of 16. Supported values: 8, 16, 24.

Returns

The function returns nothing.

Example Code

NA

Notes and Warnings

Setting a bit depth of 24 bits per sample will require 32 bits (4 bytes) of buffer space for storing each sample, with the most significant byte ignored.

AudioCodec::setChannelCount

Description

Configure the audio codec transmit and receive channel count.

Syntax

void setChannelCount(uint8_t monoStereo);

Parameters

monoStereo : number of channels. Default value of 1. Supported values: 1, 2.

Returns

The function returns nothing.

Example Code

Example: BasicInputOutput

Notes and Warnings

NA

AudioCodec::setInputMicType

Description

Configure for analog or digital input microphone type.

Syntax

Void setInputMicType(Mic_Type micType);

Parameters

micType : Input microphone type. Default value ANALOGMIC. Valid values:

  • ANALOGMIC – microphone with an analog output

  • PDMMIC – digital microphone with a PDM output

Returns

The function returns nothing.

Example Code

NA

Notes and Warnings

For analog single-ended output, connect to PA_4 for the left channel and PA_2 for the right channel.

For digital PDM output, connect the PDM clock to PB_1 and PDM data to PB_2.

AudioCodec::setInputLRMux

Description

Configure input left right channel multiplexing.

Syntax

void setInputLRMux(uint32_t mux);

Parameters

mux : desired left right audio channel multiplexing setting. Default value RX_CH_LR. Valid values:

  • RX_CH_LR

  • RX_CH_RL

  • RX_CH_LL

  • RX_CH_RR

Returns

The function returns nothing.

Example Code

NA

Notes and Warnings

In mono channel mode, both RX_CH_LR and RX_CH_LL will result in the audio codec sampling input data from the left channel microphone. Similarly, both RX_CH_RL and RX_CH_RR will result in the audio codec sampling input data from the right channel microphone.

In stereo channel mode, RX_CH_RL will switch the positions of input data sampled from the microphones. RX_CH_RR and RX_CH_LL will result in duplicated samples from the right and left microphones respectively.** **

AudioCodec::setDMicBoost

Description

Configure boost gain for digital microphone input.

Syntax

void setDMicBoost(uint32_t leftBoost, uint32_t rightBoost);

Parameters

leftBoost : boost gain for left channel digital microphone input

rightBoost: boost gain for right channel digital microphone input

Valid boost gain values:

  • 0 : 0dB

  • 1 : 12dB

  • 2 : 24dB

  • 3 : 36dB

Returns

The function returns nothing.

Example Code

NA

Notes and Warnings

NA

AudioCodec::setAMicBoost

Description

Configure boost gain for analog microphone input.

Syntax

void setAMicBoost(uint32_t leftBoost, uint32_t rightBoost);

Parameters

leftBoost : boost gain for left channel analog microphone input

rightBoost : boost gain for right channel analog microphone input

Valid boost gain values:

  • 0 : 0dB

  • 1 : 20dB

  • 2 : 30dB

  • 3 : 40dB

Returns

The function returns nothing.

Example Code

NA

Notes and Warnings

Only use this function if additional gain is required after using setADCGain function.

AudioCodec::setADCGain

Description

Configure gain of ADC used to acquire analog input.

Syntax

void setADCGain(uint32_t leftGain, uint32_t rightGain);

Parameters

leftGain : Gain for left channel ADC

rightGain : Gain for right channel ADC

Valid value range is from 0x00 to 0x7f. Gain increases by 0.375dB for every increment in value:

  • 0x00 : -17.625dB

  • 0x01 : -17.25dB

  • 0x2f : 0dB

  • 0x30 : 0.375dB

  • 0x7f : 30dB

Returns

The function returns nothing.

Example Code

NA

Notes and Warnings

NA

AudioCodec::muteInput

Description

Mute input audio data stream.

Syntax

void muteInput(uint8_t leftMute, uint8_t rightMute);

Parameters

leftMute : 1 to mute left channel input, 0 to unmute

rightMute : 1 to mute right channel input, 0 to unmute

Returns

The function returns nothing.

Example Code

NA

Notes and Warnings

NA

AudioCodec::setOutputVolume

Description

Configure output audio volume.

Syntax

void setOutputVolume(uint8_t leftVol, uint8_t rightVol);

Parameters

leftVol : left channel output volume

rightVol : right channel output volume

Valid value ranges from 0 to 100, corresponding to a volume of -65.625dB to 0dB.

Returns

The function returns nothing.

Example Code

Example: BasicInputOutput

Notes and Warnings

NA

AudioCodec::muteOutput

Description

Mute output audio.

Syntax

void muteOutput(uint8_t leftMute, uint8_t rightMute);

Parameters

leftMute : 1 to mute left channel output, 0 to unmute

rightMute : 1 to mute right channel output, 0 to unmute

Returns

The function returns nothing.

Example Code

NA

Notes and Warnings

NA

AudioCodec::writeAvaliable

Description

Check for free buffer page available for data write.

Syntax

bool writeAvaliable();

Parameters

The function requires no input parameter.

Returns

Returns true if there is a buffer page that is available for writing data into. Returns false if all buffer pages are full.

Example Code

Example: BasicInputOutput

Notes and Warnings

NA

AudioCodec::writeDataPage

Description

Write audio data to an available buffer page.

Syntax

uint32_t writeDataPage(int8_t*src, uint32_t len);

uint32_t writeDataPage(int16_t*src, uint32_t len);

Parameters

src : pointer to array containing audio samples to write to audio codec.

len : number of audio samples in array.

Returns

The function returns the number of audio samples written to the audio codec.

Example Code

Example: BasicInputOutput

Notes and Warnings

NA

AudioCodec::readAvaliable

Description

Check for buffer page with new data available for read.

Syntax

bool readAvaliable();

Parameters

The function requires no input parameter.

Returns

Returns true if there is a buffer page with new data that is ready for reading data from. Returns false if all buffer pages are empty.

Example Code

Example: BasicInputOutput

Notes and Warnings

NA

AudioCodec::readDataPage

Description

Read audio data from a ready buffer page.

Syntax

uint32_t readDataPage(int8_t*dst, uint32_t len);

uint32_t readDataPage(int16_t*dst, uint32_t len);

Parameters

dst : pointer to array to contain audio samples read from audio codec.

len : number of audio samples to read.

Returns

The function returns the number of audio samples read from the audio codec.

Example Code

Example: BasicInputOutput

Notes and Warnings

NA

AudioCodec::setWriteCallback

Description

Set a callback function to be notified when a free buffer page is available for write.

Syntax

void setWriteCallback(void(*writeCB)(void));

Parameters

writeCB: function to be called when a buffer page becomes available for data write. Takes no arguments and returns nothing

Returns

The function returns nothing.

Example Code

NA

Notes and Warnings

After starting the audio codec with AudioCodec::begin(), the callback function will be called each time the audio codec finishes outputting the data in a buffer page.

AudioCodec::setReadCallback

Description

Set a callback function to be notified when a buffer page with new data is available for read.

Syntax

void setReadCallback(void(*readCB)(void));

Parameters

readCB: function to be called when a buffer page with new data becomes available for data read. Takes no arguments and returns nothing

Returns

The function returns nothing.

Example Code

NA

Notes and Warnings

After starting the audio codec with AudioCodec::begin(), the callback function will be called each time the audio codec fills up a buffer page with newly acquired audio samples.