PWMDriverSTM32 Class Reference

Audio output to PWM pins for STM32. We use one timer to generate the sample rate and one timer for the PWM signal. More...

#include <PWMDriverSTM32.h>

Inheritance diagram for PWMDriverSTM32:

Public Member Functions
PWMConfig &	audioInfo ()
virtual int	availableForWrite ()
bool	begin (PWMConfig cfg)
virtual PWMConfig	defaultConfig ()
virtual int	effectiveOutputSampleRate ()
	Provides the effective sample rate.
virtual void	end () override
uint32_t	framesPerSecond ()
bool	isTimerStarted ()
void	setBuffer (BaseBuffer< uint8_t > *buffer)
void	setPWMTimer (HardwareTimer &t)
	Defines the timer which is used to generate the PWM signal.
uint32_t	underflowsPerSecond ()
void	updateStatistics ()
virtual size_t	write (const uint8_t *data, size_t len)

Protected Member Functions
virtual int	decimation ()
	Decimation factor to reduce the sample rate.
void	deleteBuffer ()
virtual bool	isDecimateActive ()
virtual int	maxChannels ()
	One timer supports max 4 output pins.
virtual int	maxOutputValue ()
	provides the max value for the configured resulution
virtual int	maxSampleRate ()
	Provides the max working sample rate.
virtual int	nextValue ()
	determines the next scaled value
void	playNextFrame ()
	writes the next frame to the output pins
virtual void	pwmWrite (int channel, int value)
virtual void	setupPWM ()
	Setup PWM Pins.
virtual void	setupTimer ()
virtual void	startTimer () override

Static Protected Member Functions
static void	defaultPWMAudioOutputCallback (void *obj)
	timer callback: write the next frame to the pins

Protected Attributes
AudioInfo	actual_info
PWMConfig	audio_config
BaseBuffer< uint8_t > *	buffer = nullptr
Decimate	decimate
int	decimation_factor = 0
uint32_t	frame_count = 0
uint32_t	frame_size = 0
uint32_t	frames_per_second = 0
bool	is_blocking_write = true
bool	is_timer_started = false
int64_t	max_value
HardwareTimer *	p_pwm_timer = nullptr
PWM	pwm
TimerAlarmRepeating	ticker
uint32_t	time_1_sec
uint32_t	underflow_count = 0
uint32_t	underflow_per_second = 0

Detailed Description

Audio output to PWM pins for STM32. We use one timer to generate the sample rate and one timer for the PWM signal.

Author

Phil Schatzmann

Copyright

GPLv3

Member Function Documentation

decimation()

virtual int decimation ( )

inlineprotectedvirtualinherited

Decimation factor to reduce the sample rate.

Reimplemented in PWMDriverRenesas.

end()

virtual void end ( )

inlineoverridevirtual

Reimplemented from DriverPWMBase.

isDecimateActive()

virtual bool isDecimateActive ( )

inlineprotectedvirtualinherited

The requested sampling rate is too hight: we only process half of the samples so we can half the sampling rate

maxChannels()

virtual int maxChannels ( )

inlineprotectedvirtual

One timer supports max 4 output pins.

Implements DriverPWMBase.

maxOutputValue()

virtual int maxOutputValue ( )

inlineprotectedvirtual

provides the max value for the configured resulution

Implements DriverPWMBase.

maxSampleRate()

virtual int maxSampleRate ( )

inlineprotectedvirtualinherited

Provides the max working sample rate.

Reimplemented in PWMDriverRenesas.

pwmWrite()

virtual void pwmWrite ( int  channel, int  value  )

inlineprotectedvirtual

write a pwm value to the indicated channel. The max value depends on the resolution

Implements DriverPWMBase.

setBuffer()

void setBuffer ( BaseBuffer< uint8_t > *  buffer )

inlineinherited

You can assign your own custom buffer impelementation: must be allocated on the heap and will be cleaned up by this class

setupPWM()

virtual void setupPWM ( )

inlineprotectedvirtual

Setup PWM Pins.

Implements DriverPWMBase.

setupTimer()

virtual void setupTimer ( )

inlineprotectedvirtual

Implements DriverPWMBase.

startTimer()

virtual void startTimer ( )

inlineoverrideprotectedvirtual

when we get the first write -> we activate the timer to start with the output of data

Implements DriverPWMBase.

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The documentation for this class was generated from the following file:

• src/AudioTools/CoreAudio/AudioPWM/PWMDriverSTM32.h