134 lines
6.1 KiB
Plaintext
134 lines
6.1 KiB
Plaintext
/**
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@page I2S_AUDIO I2S Audio example
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@verbatim
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******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
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* @file I2S/I2S_Audio/readme.txt
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* @author MCD Application Team
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* @brief Description of the I2S Audio example.
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******************************************************************************
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* @attention
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*
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* Copyright (c) 2017 STMicroelectronics.
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* All rights reserved.
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*
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* This software is licensed under terms that can be found in the LICENSE file
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* in the root directory of this software component.
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* If no LICENSE file comes with this software, it is provided AS-IS.
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*
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******************************************************************************
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@endverbatim
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@par Example Description
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Basic implementation of audio features. This example allows playing an audio
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file with an external codec on the STM324xG_EVAL board through the I2S
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peripheral using DMA transfer.
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In this example the I2S input clock, provided by a dedicated PLL (PLLI2S), is
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configured to have an audio sampling frequency at 48 KHz with Master clock enabled.
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This example uses an audio codec driver which consists of three independent layers:
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- Codec Hardware layer: which controls and communicates with the audio codec
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(CS43L22) implemented on the evaluation board.
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- MAL (Media Access Layer): which controls and interfaces with storage media
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storing or providing the audio file/stream.
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- The high layer: which implements overall control and interfacing API allowing
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to perform basic audio operations (Init, Play, Pause, Resume, Stop, Volume
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control and audio file pointer management)
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In this example the audio file is stored in the internal flash memory (Stereo,
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16-bit, 48 KHz). The analog output device is automatically detected (Speaker or
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Headphone) when the Headphone is plugged/unplugged in/from the audio jack of the
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evaluation board. The example also manages information display and control interface
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through push buttons:
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- When the application is Playing audio file:
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+ Key : Pause
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+ Tamper: Volume UP
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+ Wakeup: Volume DOWN
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- When the application is Paused:
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+ Key : Play
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+ Tamper: Switch output target to Headphone
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+ Wakeup: Switch output target to Speaker
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This example plays the audio file stored in internal flash memory and replay it
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when it reach end of file. But it can be tailored to used different media storage
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devices; SDCard (through SDIO), external Memory (through FSMC) ...) or to play
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in streaming mode (ie. from USB port in device or host mode). In this case, Circular
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DMA mode should be preferred (by enabling the define AUDIO_MAL_MODE_CIRCULAR in
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stm324xg_eval_audio.h file).
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List of Known Limitations and more detailed user notes are provided in file
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stm324xg_eval_audio.c (under Drivers/BSP/STM324xG_EVAL)
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The provided sample audio file, under "/Utilities/Media/Audio/audio_sample_wav.bin"
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that must be stored in internal flash memory, is extracted from:
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- Title: artofgardens-instr
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- Artist/Composer: Dan O'Connor
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- Creative Commons license: Attribution 3.0 United States
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Please read the license following this link:
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http://creativecommons.org/licenses/by/3.0/us/
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@note When using the Speaker, if the audio file quality is not high enough, the speaker output
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may produce high and uncomfortable noise level. To avoid this issue, to use speaker
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output properly, try to increase audio file sampling rate (typically higher than 48KHz).
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This operation will lead to larger file size.
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@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
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based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
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a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
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than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
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To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
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@note The application needs to ensure that the SysTick time base is always set to 1 millisecond
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to have correct HAL operation.
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@par Keywords
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Connectivity, I2S, DMA, Audio codec
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@par Directory contents
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- I2S/I2S_Audio/Inc/stm32f4xx_hal_conf.h HAL configuration file
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- I2S/I2S_Audio/Inc/stm32f4xx_it.h Interrupt handlers header file
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- I2S/I2S_Audio/Inc/main.h Main program header file
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- I2S/I2S_Audio/Src/audio_if.h Audio Out (playback) interface API header file
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- I2S/I2S_Audio/Src/stm32f4xx_it.c Interrupt handlers
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- I2S/I2S_Audio/Src/main.c Main program
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- I2S/I2S_Audio/Src/system_stm32f4xx.c STM32F4xx system clock configuration file
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- I2S/I2S_Audio/Src/stm32f4xx_hal_msp.c HAL MSP module
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- I2S/I2S_Audio/Src/audio_if.c Audio Out (playback) interface API file
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@par Hardware and Software environment
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- This example runs on STM32F407xx/417xx devices.
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- This example has been tested with STMicroelectronics STM324xG-EVAL RevC
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evaluation boards and can be easily tailored to any other supported device
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and development board.
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- STM324xG-EVAL RevC Set-up
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- Please ensure that the jumper JP16 is in the position 2-3.
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@par How to use it ?
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- Use STLink utility, available on www.st.com or any other in system programming
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tool to load "/Utilities/Media/Audio/audio_sample_wav.bin" file to the STM32
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internal flash at the address 0x08080000.
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Make sure the audio file size does not exceed 512KB. When using STLink utility change
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the audio file extension to "*.bin" in order to be able to load it directly to flash memory.
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In order to make the program work, you must do the following :
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- Open your preferred toolchain
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- Rebuild all files and load your image into target memory
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- Run the example
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@note Make sure that the tool flash loader does not erase or overwrite the
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loaded audio file at address 0x08080000 by limiting the application
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end address to 0x0807FFFF. This is already done for the example project
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- Connect a headphone or a speaker to the audio jack connector (CN11).
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*/
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