AudioCodec Class
AudioCodec Class
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(void);
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(void);
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 48000. 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(void);
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(void);
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.
