/**
@page DFSDM_PulseSkipper Description
@verbatim
******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
* @file DFSDM/DFSDM_PulseSkipper/readme.txt
* @author MCD Application Team
* @brief Description of the DFSDM audio record example.
******************************************************************************
* @attention
*
* Copyright (c) 2017 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
@endverbatim
@par Example Description
This example shows how to use the DFSDM HAL API to perform stereo audio recording.
For this audio record we will use two MP34DT01 digital microphones mounted on the board(2micros) or
those integrated on extension boards( 2 micro from MB1299).
MP34DT01 runs with a clock frequency from 1MHz to 3,25MHz.
This clock frequency has to be delivered by DFSDM. So first channel of DFSDM will be
configurated to enable output clock generation, to choose audio clock as output clock source,
and output clock divider will be set to generate output clock on MP34DT01 frequency clock range.
Audio clock will be configurated to 49.142MHz, so DFSDM output clock divider will be set to 24.
The user can select 2 microphones at the same time from the extension board MB1299
if it is fitted otherwise the 2 microphones embedded on STM32F413H-Discovery will be used.
//#define PLAY_DFSDM2_DATIN01 /* Use Mics: U2 and U3 from extension board */
//#define PLAY_DFSDM2_DATIN06 /* Use Mics: U2 and U4 from extension board */
//#define PLAY_DFSDM2_DATIN07 /* Use Mics: U2 and U5 from extension board */
//#define PLAY_DFSDM2_DATIN16 /* Use Mics: U3 and U4 from extension board */
//#define PLAY_DFSDM2_DATIN17 /* Use Mics: U3 and U5 from extension board */
//#define PLAY_DFSDM2_DATIN67 /* Use Mics: U4 and U5 from extension board */
#define PLAY_DFSDM12_DATIN10 /* Use Mics: U1 and U2 from extension board or U16 and U17 from discovery */
//#define PLAY_DFSDM12_DATIN11 /* Use Mics: U1 and U3 from extension board */
//#define PLAY_DFSDM12_DATIN16 /* Use Mics: U1 and U4 from extension board */
//#define PLAY_DFSDM12_DATIN17 /* Use Mics: U1 and U5 from extension board */
In addition, this example shows how to implement a pulse skipper to generate a delay on a selected channel.
In main.h, uncomment #define USE_CHANNEL_DELAY to enable pulse skipper.
Purpose of pulses skipper is to implement delay line for given input channel(s).
Given number of samples from input serial data stream will be discarded before they enter into the filter.
The implementation of the Clock skipping is based on block MultiChannelDelay, Tim3 and TIM4.
The clock injected to digital microphones is provided by DFSDM2 clock out. It is distributed to
OR gates, Trigger inputs of two timers and DFSDM1_CKOUT and DFSDM2_CKOUT to generate output clock
signal for DFSDM pins.
@note Refer to the application note AN4957 "How to synchronize the DFSDMs filters
and how to program the pulse skipper on STM32F413/423 line devices" for more details.
For each two Microphones selected, the user can select in which channel to generate pulse delay.
#if defined(PLAY_DFSDM12_DATIN10)
/* Select channel to generate delay: either DFSDM1 CH1 or DFSDM2 CH0 */
//#define GENERATE_DELAY_DFSDM1_CH1
//#define GENERATE_DELAY_DFSDM2_CH0
#elif defined(PLAY_DFSDM12_DATIN11)
/* Select channel to generate delay: either DFSDM1 CH1 or DFSDM2 CH1 */
//#define GENERATE_DELAY_DFSDM1_CH1
//#define GENERATE_DELAY_DFSDM2_CH1
...
#endif
Playback of the recorded data will be performed on headset using HAL_I2S and WM8994 audio codec.
A circular playback buffer will be filled as soon as recorded data are available.
When half left and right buffers will be filled, we put first parts of left and right channels data
on first half of playback buffer.
When left and right buffers will be full filled, we put second parts of left and right channels data
on second half of playback buffer.
@note Care must be taken when using HAL_Delay(), this function provides accurate
delay (in milliseconds) based on variable incremented in SysTick ISR. This
implies that if HAL_Delay() is called from a peripheral ISR process, then
the SysTick interrupt must have higher priority (numerically lower)
than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
@note The application need to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@par Keywords
Audio, DFSDM, Pulse skipper, Audio record, Digital Microphone, MP34DT01, Playback, Audio codec
@par Directory contents
- DFSDM/DFSDM_PulseSkipper/Src/main.c Main program
- DFSDM/DFSDM_PulseSkipper/Src/system_stm32f4xx.c STM32F4xx system source file
- DFSDM/DFSDM_PulseSkipper/Src/stm32f4xx_it.c Interrupt handlers
- DFSDM/DFSDM_PulseSkipper/Inc/main.h Main program header file
- DFSDM/DFSDM_PulseSkipper/Inc/stm32f4xx_hal_conf.h HAL configuration file
- DFSDM/DFSDM_PulseSkipper/Inc/stm32f4xx_it.h Interrupt handlers header file
@par Hardware and Software environment
- This example runs on STM32F413xx devices.
- This example has been tested with STMicroelectronics STM32F413ZH-Discovery revB
board and can be easily tailored to any other supported device
and development board.
- STM32F413H-Discovery Set-up :
- Plug headset on AUDIO JACK connector CN5.
@par How to use it ?
In order to make the program work, you must do the following :
- Open your preferred toolchain
- Rebuild all files and load your image into target memory
- Run the example
*/
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