查看“DFSDM internal peripheral”的源代码

==Article purpose==
The purpose of this article is to
* briefly introduce the DFSDM  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, when needed, how to configure the DFSDM peripheral.

==Peripheral overview==
The '''DFSDM''' peripheral (Digital Filter for Sigma-Delta Modulator) is used as a generic ADC. It benefits from external analog frontend interfaces and internal digital filters.<br />
It can be used in various applications<ref name="DFSDM training">[https://st-onlinetraining.s3.amazonaws.com/STM32L4_System_Digital_Filter_for_SD_Modulators_interface_(DFSDM)/index.html STM32L4 System Digital Filter for SD Modulators interface], online DFSDM training from STMicroelectronics</ref> such as: '''audio record''' with MEMS microphones, '''energy measurement''' with STPMS2<ref name="STPMS2">[https://www.st.com/en/data-converters/stpms2.html STPMS2] "Smart sensor" device</ref> for electricity meters or motor control...

===Features===
The '''DFSDM''' peripheral provides several features, among which:
* Up to 8 external analog frontend serial interfaces (SPI, manchester coded single wire interface, clock output), for various sigma-delta modulators
* Up to 8 internal digital parallel interfaces (from internal ADC<ref name="ADC internal peripheral">[[ADC internal peripheral]]</ref> or memory data stream via DMA<ref name="DMA internal peripheral">[[DMA internal peripheral]]</ref> or CPU)
* Up to 6 digital filters, that offers up to 24-bit final ADC resolution
* Conversions that can be launched continuously, or using various triggers: by software, TIM<ref name="TIM internal peripheral">[[TIM internal peripheral]]</ref>, LPTIM<ref name="LPTIM internal peripheral">[[LPTIM internal peripheral]]</ref>, EXTI<ref name="EXTI internal peripheral">[[EXTI internal peripheral]]</ref> or synchronously with DFSDM filter 0
* Event detectors: analog watchdog high/low thresholds, short-circuit detector, extremes detector
* Break generation to TIM<ref name="TIM internal peripheral"/> on analog watchdog or short-circuit detector events
Refer to [[STM32MP15 resources#Reference manuals|STM32MP15 reference manuals]] for the complete features list, and to the software components, introduced below, to know which features are really implemented.

===Security support===
The DFSDM is a '''non-secure''' peripheral.

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

===Runtime===
====Overview====
The DFSDM can be allocated to:
* the Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-A7 non-secure core to be used under Linux<sup>&reg;</sup> with the [[IIO overview|IIO]] or [[ALSA overview|ALSA]] framework
{{ReviewsComments|ArnaudP W837: "with the [[IIO overview|IIO]] or [[ALSA overview|ALSA]] framework" -> "through the [[IIO overview|IIO]] or [[ALSA overview|ALSA]] interface}}
or
* the Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-M4 for using in STM32Cube with [[STM32CubeMP1 architecture|STM32Cube DFSDM driver]].

The [[#Peripheral assignment|peripheral assignment]] chapter describes which peripheral instance can be assigned to which context.

====Software frameworks====
{{:Internal_peripherals_software_table_template}}
 | Analog
 | [[DFSDM internal peripheral|DFSDM]]
 | 
 | [[IIO overview|Linux IIO framework]]<br>[[ALSA overview|Linux ALSA framework]]
 | [[STM32CubeMP1 architecture|STM32Cube DFSDM driver]]
 |
 |-
 |}

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

For the Linux kernel configuration, please refer to [[DFSDM device tree configuration]] and [[DFSDM Linux driver]] articles.

====Peripheral assignment====
{{:Internal_peripherals_assignment_table_template}}
<onlyinclude>
 | rowspan="1" | Analog
 | rowspan="1" | [[DFSDM internal peripheral|DFSDM]]
 | DFSDM
 | 
 | <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==
See:
* ''STM32L4 System Digital Filter for SD Modulators interface''<ref name="DFSDM training"/>, online DFSDM training with application examples from STMicroelectronics

* ''Getting started with sigma-delta digital interface''<ref>[https://www.st.com/content/ccc/resource/technical/document/application_note/group0/b2/44/42/9d/46/b4/4d/34/DM00354333/files/DM00354333.pdf/jcr:content/translations/en.DM00354333.pdf Getting started with sigma-delta digital interface], application note from STMicroelectronics</ref>, application note from STMicroelectronics

==References==
<references/>