查看“SAI internal peripheral”的源代码

==Article purpose==
The purpose of this article is to:
* briefly introduce the SAI peripheral and its main features
* indicate the level of security supported by this hardware block
* explain how each instance can be allocated to the three runtime contexts and linked to the corresponding software components
* explain how to configure the SAI peripheral.

==Peripheral overview==
The SAI (Serial Audio Interface) offers a wide set of audio protocols, such as: I2S standards (LSB or MSB-justified), PCM/DSP, TDM and S/PDIF. The SAI contains two independent audio sub-blocks. Each sub-block has its own clock generator and I/O line controller, and can be configured either as transmitter or receiver.

===Features===
Refer to [[STM32MP15 resources#Reference manuals|STM32MP15 reference manuals]] for the complete feature list, and to the software components, introduced below, to see which features are implemented.<br>

===Security support===
All the SAI instances are '''non secure''' peripherals.

==Peripheral usage and associated software==
===Boot time===
The SAI is not used at boot time.

===Runtime===
====Overview====
SAI instances can be allocated to:
* the Cortex-A7 non-secure for use in Linux with [[ALSA_overview|ALSA framework]]
* the Cortex-M4 for use in STM32Cube with [[STM32CubeMP1 architecture|STM32Cube SAI driver]]

Chapter [[#Peripheral assignment]] exposes which instance can be assigned to which context.

====Software frameworks====
{{:Internal_peripherals_software_table_template}}
 | Audio
 | [[SAI internal peripheral|SAI]]
 | 
 | [[ALSA_overview|ALSA framework]]
 | [[STM32CubeMP1 architecture|STM32Cube SAI driver]]
 |
 |-
 |}

====Peripheral configuration====
The configuration is applied by the firmware running in the context to which the peripheral is assigned. The configuration can be done alone via the [[STM32CubeMX]] tool for all internal peripherals, then manually completed (particularly for external peripherals), according to the information given in the corresponding software framework article.

=====Configuration in Cortex-A7 non-secure software=====
When the Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-A7 core operates in non-secure access mode, the SAI is controlled by the Linux kernel framework.
Refer to [[SAI Linux driver]] to drive the SAI through Linux kernel [[ALSA_overview|ALSA framework]]. Refer to [[Soundcard configuration]] and [[SAI device tree configuration]] to configure the SAI through the Linux kernel device tree<ref>[[Device tree]]</ref>.

=====Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-M4 software configuration =====
{{ReviewsComments|To be updated}}

====Peripheral assignment====
{{:Internal_peripherals_assignment_table_template}}
<onlyinclude>
 | rowspan="4" | Audio
 | rowspan="4" | [[SAI internal peripheral|SAI]]
 | SAI1
 | 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | Assignment (single choice)
 |-
 | SAI2
 | 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | Assignment (single choice)
 |-
 | SAI3
 | 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | Assignment (single choice)
 |-
 | SAI4
 | 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | Assignment (single choice)
 |-
</onlyinclude>
 |}

==How to go further==
STM32H7 SAI training <ref> [https://www.st.com/content/ccc/resource/training/technical/product_training/group0/d3/c0/b0/0e/fe/eb/40/a9/STM32H7-Peripheral-Serial-Audio-Interface_SAI/files/STM32H7-Peripheral-Serial-Audio-Interface_SAI.pdf/_jcr_content/translations/en.STM32H7-Peripheral-Serial-Audio-Interface_SAI.pdf STM32H7 SAI training]</ref> introduces the SAI features and applications. The SAI versions in STM32H7 and STM32MP15 are very close. In consequence this training is also relevant for STM32MP15. The user should refer to the [[STM32MP15 resources#Reference manuals|STM32MP15 reference manuals]] for a complete description.

==References==
<references/>