dac_dds.h File Reference

Use a DAC to play a buffer of samples. More...

Detailed Description

Use a DAC to play a buffer of samples.

         A buffer of (audio) samples can be played on a DAC with
         a given sample rate.
         To supply a steady stream of samples, a double buffer is
         used.
         While buffer A is played on the DAC the user can fill buffer
         B with the next batch of samples by calling @ref dac_dds_play
         again. Once buffer A has finished playing, buffer B will
         automatically be used instead.

         A callback can be registered that signals when the next buffer
         is ready to be filled.
         Do not do the actual buffer filling inside the callback as this
         is called from the timer context that is used to play the samples.
         Instead, use it to wake a thread that then provides the samples
         and calls @ref dac_dds_play.
         If the next sample buffer is already prepared, you can also call
         `dac_dds_play` within the callback, just don't do any I/O or
         heavy processing.

Author

Benjamin Valentin benpi.nosp@m.cco@.nosp@m.beuth.nosp@m.-hoc.nosp@m.hschu.nosp@m.le.d.nosp@m.e

Definition in file dac_dds.h.

#include <stddef.h>
#include <stdint.h>
#include <limits.h>
#include "periph/dac.h"
#include "periph/timer.h"

Include dependency graph for dac_dds.h:

Go to the source code of this file.

Data Structures
struct	dac_dds_params_t
	Configuration struct for a DAC DDS channel. More...

Macros
#define	DAC_FLAG_8BIT   (0x0)
	A sample has a resolution of 8 bit.
#define	DAC_FLAG_16BIT   (0x1)
	A sample has a resolution of 16 bit.

Typedefs
typedef void(*	dac_dds_cb_t) (void *arg)
	The callback that will be called when the end of the current sample buffer has been reached.
typedef uint8_t	dac_dds_t
	Index of the DAC DDS channel.

Functions
void	dac_dds_init (dac_dds_t dac, uint16_t sample_rate, uint8_t flags, dac_dds_cb_t cb, void *cb_arg)
	Initialize a DAC for playing audio samples A user defined callback can be provided that will be called when the next buffer can be queued.
void	dac_dds_set_cb (dac_dds_t dac, dac_dds_cb_t cb, void *cb_arg)
	Change the 'buffer done' callback.
bool	dac_dds_play (dac_dds_t dac, const void *buf, size_t len)
	Play a buffer of (audio) samples on a DAC.
void	dac_dds_stop (dac_dds_t dac)
	Stop playback of the current sample buffer.