73 lines
2.1 KiB
ReStructuredText
73 lines
2.1 KiB
ReStructuredText
.. _nrf-system-off-sample:
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nRF5x System Off demo
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#####################
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Overview
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********
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This sample can be used for basic power measurement and as an example of
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deep sleep on Nordic platforms. The functional behavior is:
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* Busy-wait for 2 seconds
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* Sleep for 2 seconds without device power control
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* Sleep for 2 seconds after turning UART off, which reduces current draw
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by a couple hundred uA
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* Turn the system off after enabling wakeup through a button press
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A power monitor will be able to distinguish among these states.
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This sample also demonstrates the use of a :c:func:`SYS_INIT()` call to
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disable the deep sleep functionality before the kernel starts, which
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prevents the board from powering down during initialization of drivers
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that use unbounded delays to wait for startup.
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RAM Retention
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=============
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On nRF52 platforms this also can demonstrate RAM retention. By selecting
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``CONFIG_APP_RETENTION=y`` state related to number of boots, number of times
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system off was entered, and total uptime since initial power-on are retained
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in a checksummed data structure. The POWER peripheral is configured to keep
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the containing RAM section powered while in system-off mode.
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Requirements
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************
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This application uses nRF51 DK or nRF52 DK board for the demo.
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Building, Flashing and Running
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******************************
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.. zephyr-app-commands::
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:zephyr-app: samples/boards/nrf52/system_off
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:board: nrf52dk_nrf52832
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:goals: build flash
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:compact:
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Running:
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1. Open UART terminal.
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2. Power Cycle Device.
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3. Device will demonstrate two activity levels which can be measured.
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4. Device will demonstrate long sleep at minimal non-off power.
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5. Device will turn itself off using deep sleep state 1. Press Button 1
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to wake the device and restart the application as if it had been
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powered back on.
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Sample Output
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=================
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nRF52 core output
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-----------------
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.. code-block:: console
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*** Booting Zephyr OS build v2.3.0-rc1-204-g5f2eb85f728d ***
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nrf52dk_nrf52832 system off demo
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Busy-wait 2 s
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Busy-wait 2 s with UART off
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Sleep 2 s
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Sleep 2 s with UART off
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Entering system off; press BUTTON1 to restart
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