Microphone

Maple driver for microphone input devices More...

Files
file	sip.h
	Definitions for using the Sound Input Peripheral.

Data Structures
struct	sip_state_t
	SIP status structure. More...

Macros
#define	SIP_SUBCOMMAND_GET_SAMPLES   0x01
	Get recorded samples from the microphone device.
#define	SIP_SUBCOMMAND_BASIC_CTRL   0x02
	Start and stop sampling.
#define	SIP_MIN_GAIN   0x00
	Minimum microphone gain.
#define	SIP_DEFAULT_GAIN   0x0F
	Default microphone gain.
#define	SIP_MAX_GAIN   0x1F
	Maximum microphone gain.
#define	SIP_SAMPLE_16BIT_SIGNED   0x00
	Record 16-bit signed integer samples.
#define	SIP_SAMPLE_8BIT_ULAW   0x01
	Record 8-bit ulaw samples.
#define	SIP_SAMPLE_11KHZ   0x00
	Record samples at 11.025kHz.
#define	SIP_SAMPLE_8KHZ   0x01
	Record samples at 8kHz.

Typedefs
typedef void(*	sip_sample_cb) (maple_device_t *dev, uint8 *samples, size_t len)
	Type for a microphone sample callback.

Functions
int	sip_set_gain (maple_device_t *dev, unsigned int g)
	Set the microphone's gain value.
int	sip_set_sample_type (maple_device_t *dev, unsigned int type)
	Set the sample type to be recorded by the microphone.
int	sip_set_frequency (maple_device_t *dev, unsigned int freq)
	Set the sample frequency to be recorded by the microphone.
int	sip_start_sampling (maple_device_t *dev, sip_sample_cb cb, int block)
	Start sampling on a microphone.
int	sip_stop_sampling (maple_device_t *dev, int block)
	Stop sampling on a microphone.

Detailed Description

Maple driver for microphone input devices

Macro Definition Documentation

SIP_DEFAULT_GAIN

#define SIP_DEFAULT_GAIN   0x0F

Default microphone gain.

SIP_MAX_GAIN

#define SIP_MAX_GAIN   0x1F

Maximum microphone gain.

SIP_MIN_GAIN

#define SIP_MIN_GAIN   0x00

Minimum microphone gain.

SIP_SAMPLE_11KHZ

#define SIP_SAMPLE_11KHZ   0x00

Record samples at 11.025kHz.

SIP_SAMPLE_16BIT_SIGNED

#define SIP_SAMPLE_16BIT_SIGNED   0x00

Record 16-bit signed integer samples.

SIP_SAMPLE_8BIT_ULAW

#define SIP_SAMPLE_8BIT_ULAW   0x01

Record 8-bit ulaw samples.

SIP_SAMPLE_8KHZ

#define SIP_SAMPLE_8KHZ   0x01

Record samples at 8kHz.

SIP_SUBCOMMAND_BASIC_CTRL

#define SIP_SUBCOMMAND_BASIC_CTRL   0x02

Start and stop sampling.

This subcommand is used with the MAPLE_COMMAND_MICCONTROL command to start and stop sampling on the microphone.

SIP_SUBCOMMAND_GET_SAMPLES

#define SIP_SUBCOMMAND_GET_SAMPLES   0x01

Get recorded samples from the microphone device.

This subcommand is used with the MAPLE_COMMAND_MICCONTROL command to fetch samples from the microphone.

Typedef Documentation

sip_sample_cb

typedef void(* sip_sample_cb) (maple_device_t *dev, uint8 *samples, size_t len)

Type for a microphone sample callback.

This is the signature that is required for a function to accept samples from the microphone as it is sampling. This function will be called about once per frame, and in an interrupt context (so it should be pretty quick to execute). Basically, all you should do in one of these is copy the samples out to your own buffer – do not do any processing on the samples in your callback other than to copy them out!

Parameters

dev	The device the samples are coming from.
samples	Pointer to the sample buffer.
len	The number of bytes in the sample buffer.

Function Documentation

sip_set_frequency()

int sip_set_frequency	(	maple_device_t *	dev,
		unsigned int	freq )

Set the sample frequency to be recorded by the microphone.

This function sets the sample frequency that the microphone will record. The default value for this is about 11.025kHz samples. You must call this prior to sip_start_sampling() if you wish to change it from the default.

Parameters

dev	The microphone device to set sample type on.
freq	The type of samples requested.

Return values

MAPLE_EOK	On success.
MAPLE_EINVALID	If freq is invalid.
MAPLE_EFAIL	If the microphone is sampling.

See also

SIP_SAMPLE_11KHZ

SIP_SAMPLE_8KHZ

sip_set_gain()

int sip_set_gain	(	maple_device_t *	dev,
		unsigned int	g )

Set the microphone's gain value.

This function sets the gain value of the specified microphone device to the value given. This should only be called prior to sampling so as to keep the amplification constant throughout the sampling process, but can be changed on the fly if you really want to.

Parameters

dev	The microphone device to set gain on.
g	The value to set as the gain.

Return values

MAPLE_EOK	On success.
MAPLE_EINVALID	If g is out of range.

See also

SIP_MIN_GAIN

SIP_DEFAULT_GAIN

SIP_MAX_GAIN

sip_set_sample_type()

int sip_set_sample_type	(	maple_device_t *	dev,
		unsigned int	type )

Set the sample type to be recorded by the microphone.

This function sets the sample type that the microphone will return. The default value for this is 16-bit signed integer samples. You must call this prior to sip_start_sampling() if you wish to change it from the default.

Parameters

dev	The microphone device to set sample type on.
type	The type of samples requested.

Return values

MAPLE_EOK	On success.
MAPLE_EINVALID	If type is invalid.
MAPLE_EFAIL	If the microphone is sampling.

See also

SIP_SAMPLE_16BIT_SIGNED

SIP_SAMPLE_8BIT_ULAW

sip_start_sampling()

int sip_start_sampling	(	maple_device_t *	dev,
		sip_sample_cb	cb,
		int	block )

Start sampling on a microphone.

This function informs a microphone it should start recording samples.

Parameters

dev	The device to start sampling on.
cb	A callback to call when samples are ready.
block	Set to 1 to wait for the SIP to start sampling. Otherwise check the is_sampling member of the status for dev to know when it has started.

Return values

MAPLE_EOK	On success.
MAPLE_EAGAIN	If the command couldn't be sent, try again later.
MAPLE_EFAIL	If the microphone is already sampling or the callback function is NULL.
MAPLE_ETIMEOUT	If the command timed out while blocking.

sip_stop_sampling()

int sip_stop_sampling	(	maple_device_t *	dev,
		int	block )

Stop sampling on a microphone.

This function informs a microphone it should stop recording samples.

Parameters

dev	The device to stop sampling on.
block	Set to 1 to wait for the SIP to stop sampling. Otherwise check the is_sampling member of the status for dev to know when it has finished.

Return values

MAPLE_EOK	On success.
MAPLE_EAGAIN	If the command couldn't be sent, try again later.
MAPLE_EFAIL	If the microphone is not sampling.
MAPLE_ETIMEOUT	If the command timed out while blocking.