Inter-Integrated Sound (I2S)

Modules
	I2S_Registers

Data Structures
struct	mxc_i2s_req_t

Enumerations
enum	mxc_i2s_stereo_t
enum	mxc_i2s_polarity_t
enum	mxc_i2s_bitorder_t
enum	mxc_i2s_justify_t
enum	mxc_i2s_clksrc_t
enum	mxc_i2s_wsize_t
enum	mxc_i2s_adjust_t
enum	mxc_i2s_ch_mode_t

Functions
int	MXC_I2S_Init (mxc_i2s_req_t *req)
int	MXC_I2S_Shutdown (void)
int	MXC_I2S_ConfigData (mxc_i2s_req_t *req)
int	MXC_I2S_SelectClockSource (mxc_i2s_clksrc_t clk_src, uint32_t freq_ext)
void	MXC_I2S_TXEnable (void)
void	MXC_I2S_TXDisable (void)
void	MXC_I2S_RXEnable (void)
void	MXC_I2S_RXDisable (void)
int	MXC_I2S_SetRXThreshold (uint8_t threshold)
int	MXC_I2S_SetFrequency (mxc_i2s_ch_mode_t mode, uint16_t clkdiv)
int	MXC_I2S_SetSampleRate (uint32_t smpl_rate, mxc_i2s_wsize_t smpl_sz)
int	MXC_I2S_GetSampleRate (void)
int	MXC_I2S_CalculateClockDiv (uint32_t smpl_rate, mxc_i2s_wsize_t smpl_sz)
void	MXC_I2S_Flush (void)
int	MXC_I2S_FillTXFIFO (void *txData, mxc_i2s_wsize_t wordSize, int len, int smpl_cnt)
int	MXC_I2S_ReadRXFIFO (void *rxData, mxc_i2s_wsize_t wordSize, int len, int smpl_cnt)
void	MXC_I2S_EnableInt (uint32_t flags)
void	MXC_I2S_DisableInt (uint32_t flags)
int	MXC_I2S_GetFlags (void)
void	MXC_I2S_ClearFlags (uint32_t flags)
int	MXC_I2S_Transaction (mxc_i2s_req_t *i2s_req)
int	MXC_I2S_TransactionAsync (mxc_i2s_req_t *i2s_req)
int	MXC_I2S_TXDMAConfig (void *src_addr, int len)
int	MXC_I2S_RXDMAConfig (void *dest_addr, int len)
void	MXC_I2S_Handler (void)
void	MXC_I2S_RegisterDMACallback (void(*callback)(int, int))
void	MXC_I2S_RegisterAsyncCallback (void(*callback)(int))

Variables
mxc_i2s_samplesize_t	sampleSize
uint8_t	bitsWord

Detailed Description

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Data Structure Documentation

mxc_i2s_req_t

struct mxc_i2s_req_t

I2S Configuration Struct.

Most common audio configurations.

---

| Audio Sample | bitsWord | sampleSize | wordSize | | Width / Samples | | | mxc_i2s_wsize_t | |---------------------------------------------------------------—| | 8 bits / 16 | 8 | 8 | MXC_I2S_WSIZE_BYTE | | 16 bits / 32 | 16 | 16 | MXC_I2S_WSIZE_HALFWORD | | 20 bits / 40 | 20 | 20 | MXC_I2S_WSIZE_WORD | | 24 bits / 48 | 24 | 24 | MXC_I2S_WSIZE_WORD | | 24 bits / 64 | 32 | 24 | MXC_I2S_WSIZE_WORD | | 32 bits / 64 | 32 | 32 | MXC_I2S_WSIZE_WORD | |_________________|__________|____________|________________________|

Data Fields
mxc_i2s_samplesize_t	sampleSize
uint8_t	bitsWord

Enumeration Type Documentation

mxc_i2s_adjust_t

enum mxc_i2s_adjust_t

I2S transaction adjust position.

This field is used to determine which bits are used if the sample size is less than the bits per word.

mxc_i2s_wsize_t

enum mxc_i2s_wsize_t

I2S transaction word size.

Set this field to the desired width for data writes and reads from the FIFO.

Enumerator
MXC_I2S_WSIZE_BYTE	Set 8-bit FIFO transactions.
MXC_I2S_WSIZE_HALFWORD	Set 16-bit FIFO transactions.
MXC_I2S_WSIZE_WORD	Set 32-bit FIFO transactions.
MXC_I2S_DATASIZE_BYTE	Legacy name. Use MXC_I2S_WSIZE_BYTE instead.
MXC_I2S_DATASIZE_HALFWORD	Legacy name. Use MXC_I2S_WSIZE_HALFWORD instead.
MXC_I2S_DATASIZE_WORD	Legacy name. Use MXC_I2S_WSIZE_WORD instead.

Function Documentation

MXC_I2S_CalculateClockDiv()

int MXC_I2S_CalculateClockDiv	(	uint32_t	smpl_rate,
		mxc_i2s_wsize_t	smpl_sz
	)

Calculates the value of the clock divider that should be used in order to get the desired sampling frequency.

Parameters

smpl_rate	Desired sampling rate.
smple_sz	The size of each I2S word.

Returns

If successful, the clock divider value. Otherwise, an error code. See Error Codes for a list of return codes.

MXC_I2S_ClearFlags()

void MXC_I2S_ClearFlags

(

uint32_t

flags

)

Clears Interrupt Flags.

Parameters

flags

Interrupt flags to be cleared

MXC_I2S_ConfigData()

int MXC_I2S_ConfigData

(

mxc_i2s_req_t *

req

)

Configure data to be transmitted based on word and sample size.

Parameters

req	see mxc_i2s_req_t I2S Request Struct

Returns

Success/Fail, see Error Codes for a list of return codes.

MXC_I2S_DisableInt()

void MXC_I2S_DisableInt

(

uint32_t

flags

)

Disable Interrupt.

Parameters

flags

Interrupt mask

MXC_I2S_EnableInt()

void MXC_I2S_EnableInt

(

uint32_t

flags

)

Enable Interrupts.

Parameters

flags

Interrupt mask

MXC_I2S_FillTXFIFO()

int MXC_I2S_FillTXFIFO	(	void *	txData,
		mxc_i2s_wsize_t	wordSize,
		int	len,
		int	smpl_cnt
	)

Fill I2S FIFO with data to transmit.

Parameters

txData	Pointer to base address of the data buffer
wordSize	Size of the data samples
len	Number of samples in the data buffer
smpl_cnt	Number of samples already sent from the data buffer

Returns

If successful the number of samples successfuly written to the FIFO. Otherwise, an error code. See Error Codes for a list of return codes.

MXC_I2S_GetFlags()

int MXC_I2S_GetFlags

(

void

)

Get the set interrupt flags.

Returns

int return the mask of the set interrupt flags

MXC_I2S_GetSampleRate()

int MXC_I2S_GetSampleRate

(

void

)

Returns the current sampling rate.

Returns

If successful, sampling rate. Otherwise, an error code. See Error Codes for a list of return codes.

MXC_I2S_Init()

int MXC_I2S_Init

(

mxc_i2s_req_t *

req

)

Initialize I2S resources.

Parameters

req	see mxc_i2s_req_t I2S Request Struct

Returns

Success/Fail, see Error Codes for a list of return codes.

MXC_I2S_ReadRXFIFO()

int MXC_I2S_ReadRXFIFO	(	void *	rxData,
		mxc_i2s_wsize_t	wordSize,
		int	len,
		int	smpl_cnt
	)

Read audio samples from I2S receive buffer.

Parameters

rxData	Pointer to data buffer that will store the audio samples
wordSize	Size of the samples in the FIFO
len	Number of samples to read
smpl_cnt	Number of samples already received in the data buffer

Returns

If successful, the number of samples actually read from the buffer. Otherwise, an error code. See Error Codes for a list of return codes.

MXC_I2S_RegisterAsyncCallback()

void MXC_I2S_RegisterAsyncCallback

(

void(*)(int)

callback

)

Sets the callback function for asynchronous I2S transactions.

Parameters

callback

Function pointer to the asynchronous transaction callback

MXC_I2S_RegisterDMACallback()

void MXC_I2S_RegisterDMACallback

(

void(*)(int, int)

callback

)

Set the callback function pointer for I2S DMA transactions.

Parameters

callback

Function pointer to the DMA callback function

MXC_I2S_RXDMAConfig()

int MXC_I2S_RXDMAConfig	(	void *	dest_addr,
		int	len
	)

Configure RX DMA transaction.

Parameters

dest_addr	destination address
len	length of the data to be received

Returns

If successful, the DMA channel number used for the request. Otherwise, an error code. See Error Codes for a list of return codes.

MXC_I2S_SelectClockSource()

int MXC_I2S_SelectClockSource	(	mxc_i2s_clksrc_t	clk_src,
		uint32_t	freq_ext
	)

This function enables and selects the source clock for I2S master mode. By default the driver assumes the ERFO will be used so this function only needs to be called if switching to/from the external clock is required for the application.

Warning

This function should be called before MXC_I2S_SetSampleRate, MXC_I2S_GetSampleRate, and MXC_I2S_CalculateClockDiv to ensure they operate correctly.

Parameters

clk_src	Selects which clock source to use.
freq_ext	Frequency of the clock source. This param only required if MXC_I2S_CLKSRC_EXT selected for clk_src.

Returns

Success/Fail, see Error Codes for a list of return codes.

MXC_I2S_SetFrequency()

int MXC_I2S_SetFrequency	(	mxc_i2s_ch_mode_t	mode,
		uint16_t	clkdiv
	)

Set I2S Frequency, automatically called by I2S_Init.

Parameters

mode	Channel mode to select clock
clkdiv	clock divider to set baudrate

Returns

Success/Fail, see Error Codes for a list of return codes.

MXC_I2S_SetRXThreshold()

int MXC_I2S_SetRXThreshold

(

uint8_t

threshold

)

Set threshold for RX FIFO

Parameters

threshold

Returns

Success/Fail, see Error Codes for a list of return codes.

MXC_I2S_SetSampleRate()

int MXC_I2S_SetSampleRate	(	uint32_t	smpl_rate,
		mxc_i2s_wsize_t	smpl_sz
	)

Sets the clock divider to provide the desired sampling rate.

Parameters

smpl_rate	The desired sampling rate.
smpl_sz	The size of each sample.

Returns

If successful, the actual sampling rate. Otherwise, an error code. See Error Codes for a list of return codes.

MXC_I2S_Shutdown()

int MXC_I2S_Shutdown

(

void

)

Release I2S, clear configuration and flush FIFOs.

Returns

Success/Fail, see Error Codes for a list of return codes.

MXC_I2S_Transaction()

int MXC_I2S_Transaction

(

mxc_i2s_req_t *

i2s_req

)

Performs a blocking I2S transaction.

Parameters

Pointer

to transaction request structure

Returns

If successful, E_NO_ERROR. Otherwise, an error code. See Error Codes for a list of return codes.

MXC_I2S_TransactionAsync()

int MXC_I2S_TransactionAsync

(

mxc_i2s_req_t *

i2s_req

)

Sets up an asynchronous I2S transaction.

Parameters

Pointer

to transaction request structure

Returns

If successful, E_NO_ERROR. Otherwise, an error code. See Error Codes for a list of return codes.

MXC_I2S_TXDMAConfig()

int MXC_I2S_TXDMAConfig	(	void *	src_addr,
		int	len
	)

Configure TX DMA transaction.

Parameters

src_addr	source address of data
len	length od the data to be transmitted

Returns

If successful, the DMA channel number used for the request. Otherwise, an error code. See Error Codes for a list of return codes.