87 lines
2.8 KiB
ReStructuredText
87 lines
2.8 KiB
ReStructuredText
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.. _stm32-pm-serial-wakeup-sample:
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STM32 PM Serial wakeup
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######################
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Overview
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********
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This sample is a minimum application to demonstrate serial wakeup functionality
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in low power context.
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.. _stm32-pm-serial-wakeup-sample-requirements:
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Requirements
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************
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1. The board should support enabling PM. For a STM32 based target, it means that
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it should support a clock source alternative to Cortex Systick that can be used
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in core sleep states, as LPTIM (:dtcompatible:`st,stm32-lptim`).
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2. The serial port used by the shell should be configured, using device tree, to
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be a functional wakeup source:
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- Clocked by an oscillator available in Stop mode (LSE, LSI) or an oscillator capable
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that can be requested dynamically by device on activity detection (HSI on STM32WB).
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- Matching oscillator sources should be enabled
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- If LSE is selected as clock source and shell serial port is a LPUART current speed
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should be adapted (9600 bauds)
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- Port should be set as "wakeup-source"
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Note: Using HSI clock is a specific
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Building and Running
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********************
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Build and flash this sample as follows, changing ``nucleo_wb55rg`` for a board
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configured to be compatible with this sample.
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.. zephyr-app-commands::
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:zephyr-app: samples/boards/stm32/power_mgmt/serial_wakeup
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:board: nucleo_wb55rg
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:goals: build flash
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:compact:
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After flashing, the shell is enabled and device enter sleep mode.
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User is able to wake up the device by typing into the shell
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PM configurations
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*****************
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By default, :kconfig:option:`CONFIG_PM_DEVICE` and :kconfig:option:`CONFIG_PM_DEVICE_RUNTIME`
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are enabled, but user can also deactivate both or former to see each configuration in play.
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Debugging
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*********
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:kconfig:option:`CONFIG_DEBUG` could be enabled to allow debug. Note that debug mode prevents
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target to reach low power consumption.
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Also note that after debug mode has been disabled, target should also be powered off in order
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to get back to normal mode and reach low power consumption.
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PM measurements on stm32l562e_dk using stm32l562e_dk PM shield
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**************************************************************
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Plug Power shield
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Plug ST-Link
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Set JP4 To 5V ST-Link
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Set SW1 to PM_SEL_VDD
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STM32Cube PowerMonitor settings to be applied:
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- Sampling Freq: max
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- Functional Mode: High
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Optimal configuration for low power consumption
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***********************************************
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In order to reach lower power consumption numbers following parameters should be taken
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into account:
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- Use a LPUART instead of a basic U(S)ART node
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- Chose LSE as clock source
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- Ensure no other oscillators are enabled (disable HSI, ...)
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- Provide "sleep" pinctrl configuration to other uart nodes.
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- Disable Debug mode
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With all these conditions matched, one can reach 10uA on stm32l562e_dk with this sample.
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