AUDIO - Mono Audio PWM DAC

Mono Audio DAC implemented with a PWM hardware module.

This software module constructs a 16-bit DAC output using two 8-bit PWM channels combined with a resistor ladder network. The interface provides functions to configure and control this software DAC.

Functions
void	pwm_dac_decrease_volume (void)
	Decreases the output volume of the DAC. More...
void	pwm_dac_flush (void)
	Flushes the sample buffer being output to the DAC. More...
uint8_t	pwm_dac_get_volume (void)
	Return the current volume. More...
void	pwm_dac_increase_volume (void)
	Increases the output volume of the DAC. More...
bool	pwm_dac_is_volume_boosted (void)
	Returns the state of the boost mode of the DAC. More...
bool	pwm_dac_is_volume_muted (void)
	Returns the state of the mute mode of the DAC. More...
void	pwm_dac_mute (bool mute)
	Mute audio if mute set to true. More...
bool	pwm_dac_output (void *sample_buffer, size_t sample_length)
	Outputs a sample buffer to the DAC. More...
void	pwm_dac_set_volume (uint8_t volume)
	Set the current volume. More...
void	pwm_dac_setup (uint32_t sample_rate_hz, uint8_t num_channels, uint8_t bits_per_sample, bool swap_channels, void(*callback)(uint32_t arg), uint32_t callback_opt, uint32_t pba_hz)
	Sets the DAC up with new settings. More...
void	pwm_dac_start (uint32_t sample_rate_hz, uint8_t num_channels, uint8_t bits_per_sample, bool swap_channels, void(*callback)(uint32_t arg), uint32_t callback_opt, uint32_t pba_hz)
	Starts the DAC. More...
void	pwm_dac_stop (void)
	Stops the DAC. More...

void pwm_dac_decrease_volume

(

void

)

Decreases the output volume of the DAC.

Note

The DAC must have been started beforehand.

References pwm_dac_output_params.

void pwm_dac_flush

(

void

)

Flushes the sample buffer being output to the DAC.

References pwm_dac_output_params, pwm_dac_output_sample(), PWM_DAC_PWM_CHANNEL_LSB, and PWM_DAC_PWM_CHANNEL_MSB.

Referenced by pwm_dac_stop().

uint8_t pwm_dac_get_volume

(

void

)

Return the current volume.

Note

The DAC must have been started beforehand.

References pwm_dac_output_params.

void pwm_dac_increase_volume

(

void

)

Increases the output volume of the DAC.

Note

The DAC must have been started beforehand.

References pwm_dac_output_params.

bool pwm_dac_is_volume_boosted

(

void

)

Returns the state of the boost mode of the DAC.

Note

The DAC must have been started beforehand.

bool pwm_dac_is_volume_muted

(

void

)

Returns the state of the mute mode of the DAC.

Note

The DAC must have been started beforehand.

void pwm_dac_mute

(

bool

mute

)

Mute audio if mute set to true.

bool pwm_dac_output	(	void *	sample_buffer,
		size_t	sample_length
	)

Outputs a sample buffer to the DAC.

Note

The DAC must have been started beforehand.

References pwm_dac_get_log2_aligned_byte_size(), pwm_dac_output_params, PWM_DAC_PWM_CHANNEL_LSB, PWM_DAC_PWM_CHANNEL_MSB, sample_buffer, and sample_length.

void pwm_dac_set_volume

(

uint8_t

volume

)

Set the current volume.

Note

The DAC must have been started beforehand.

References pwm_dac_output_params.

void pwm_dac_setup	(	uint32_t	sample_rate_hz,
		uint8_t	num_channels,
		uint8_t	bits_per_sample,
		bool	swap_channels,
		void(*)(uint32_t arg)	callback,
		uint32_t	callback_opt,
		uint32_t	pba_hz
	)

Sets the DAC up with new settings.

Note

The DAC must have been started beforehand.

References bits_per_sample, callback, callback_opt, max, min, num_channels, pwm_dac_get_log2_aligned_byte_size(), PWM_DAC_GET_SAMPLE, pwm_dac_output_params, and swap_channels.

Referenced by pwm_dac_start().

void pwm_dac_start	(	uint32_t	sample_rate_hz,
		uint8_t	num_channels,
		uint8_t	bits_per_sample,
		bool	swap_channels,
		void(*)(uint32_t arg)	callback,
		uint32_t	callback_opt,
		uint32_t	pba_hz
	)

Starts the DAC.

References callback, gpio_enable_module(), INTC_register_interrupt(), pwm_dac_output_sample(), PWM_DAC_PWM_CHANNEL_LSB, PWM_DAC_PWM_CHANNEL_MSB, pwm_dac_pwm_int_handler(), PWM_DAC_PWM_INT_LEVEL, PWM_DAC_PWM_IRQ, pwm_dac_setup(), and pwm_dac_stop().

void pwm_dac_stop

(

void

)

Stops the DAC.

References gpio_enable_gpio(), pwm_dac_flush(), pwm_dac_output_params, PWM_DAC_PWM_CHANNEL_LSB, and PWM_DAC_PWM_CHANNEL_MSB.

Referenced by pwm_dac_start().