查看“Coprocessor power management”的源代码

==Article purpose==

The purpose of this article is to give an overview of the software APIs available on the Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-M4 (also named MCU) side to handle the low power modes.

==Low power modes available on the chip==

Refer to [[STM32MP15 resources#Reference manuals|STM32MP15 reference manuals]] for the full description of the modes.<br>
The [[STM32MP15 resources#AN5109|AN5109 low power application note]] also gives details on these modes.

The modes are handled by [[RCC internal peripheral|RCC]] and [[PWR internal peripheral|PWR]] peripherals. 


The table below explains the chip hardware states corresponding to each low power mode.

Subsystem either refers to Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-A7 side (also called MPU) or Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-M4 side (also called MCU).
A mode prefixed by 'C' refers to a subsystem mode.

A platform mode is the combination of MPU and MCU modes.

{| class="st-table"
|-
! Level !! Mode !! Vddcore state !! Clocks state
|-
| rowspan="5" | Subsystem || MPU CRun || on || on
|-
| MPU CStop || on || Subsystem off
|-
| MPU CStandby || on || Subsystem off
|-
| '''MCU CRun''' || '''on''' || '''on'''
|-
| '''MCU CStop''' || '''on''' || '''Subsystem off'''
|}

{| class="st-table"
|-
! MPU mode !! MCU mode !! Platform mode !! Vddcore state !! Clocks state
|-
| CRun || CRun || Run || On || On
|-
| CStop || CRun || Run || On || On
|-
| CStandby || CRun || Run || On || On
|-
| CRun || CStop || Run || On || On
|-
| CStop || CStop || Stop/LPLV-Stop/Standby || On/Retention/Off || Off/Off/Off
|-
| CStandby || CStop || Stop/LPLV-Stop/Standby  || On/Retention/Off || Off/Off/Off
|}

===Wakeup sources===

The above modes are left due to a wakeup event.

The following table gives the list of wakeup sources available in each mode.

{| class="st-table"
|-
! Mode !! Available wakeup sources
|-
| CStop/CStandby/Stop || BOR, PVD, AVD, Vbat mon, Temp mon, LSE CSS, RTC, TAMP, USB, CEC, ETH, USART, I²C, SPI, LPTIM, IWDG, GPIO, Wakeup pins
|-
| LPLV-Stop || BOR, PVD, AVD, Vbat mon, Temp mon, LSE CSS, RTC, TAMP, IWDG, GPIO, Wakeup pins
|-
| Standby || BOR, Vbat mon, Temp mon, LSE CSS, RTC, TAMP, IWDG, Wakeup pins
|}

{{ReviewsComments|BPU W1929: How to set a wakeup source on MCU side ?}}

==Software overview==

The power HAL is used to select the Cortex-M4 low power mode.

Further information on HAL can be found here: [[STM32CubeMP1 architecture]]

{{ReviewsComments|BPU W1929: Could we mention also the access through the RPMSG ? (ex:  /sys/class/remoteproc/remoteproc0/state) ?}}

===APIs description===

The power HAL supports the following APIs related to power management:

  HAL_PWR_EnterSLEEPMode: CSleep mode is entered

  HAL_PWR_EnterStopMode: CStop mode is entered allowing Stop as the deepest platform low power mode 

  HAL_PWR_EnterStandbyMode: CStop mode is entered allowing Standby as the deepest platform low power mode

===Code source location===
[[STM32CubeMP1 Package]] provides power HAL driver:</br>
{{CodeSource | STM32CubeMP1 | Drivers/STM32MP1xx_HAL_Driver/Src/stm32mp1xx_hal_pwr.c}}

<noinclude>
[[Category:Coprocessor management STM32Cube]]
{{PublicationRequestId | 10389 | 2019-01-21 | AlainF}}
</noinclude>