zephyr

History

Tomasz Bursztyka e18fcbba5a device: Const-ify all device driver instance pointers Now that device_api attribute is unmodified at runtime, as well as all the other attributes, it is possible to switch all device driver instance to be constant. A coccinelle rule is used for this: @r_const_dev_1 disable optional_qualifier @ @@ -struct device * +const struct device * @r_const_dev_2 disable optional_qualifier @ @@ -struct device * const +const struct device * Fixes #27399 Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>		2020-09-02 13:48:13 +02:00
..
src	device: Const-ify all device driver instance pointers	2020-09-02 13:48:13 +02:00
CMakeLists.txt	…
README.rst	samples: nrf: system_off: show how to disable deep sleep	2020-07-07 15:06:08 +02:00
prj.conf	…
sample.yaml	sanitycheck: inclusive language	2020-08-27 07:04:07 -04:00

README.rst

.. _nrf-system-off-sample:

nRF5x System Off demo
#####################

Overview
********

This sample can be used for basic power measurement and as an example of
deep sleep on Nordic platforms.  The functional behavior is:

* Busy-wait for 2 seconds
* Sleep for 2 seconds without device power control
* Sleep for 2 seconds after turning UART off, which reduces current draw
  by a couple hundred uA
* Turn the system off after enabling wakeup through a button press

A power monitor will be able to distinguish among these states.

This sample also demonstrates the use of a :c:func:`SYS_INIT()` call to
disable the deep sleep functionality before the kernel starts, which
prevents the board from powering down during initialization of drivers
that use unbounded delays to wait for startup.

Requirements
************

This application uses nRF51 DK or nRF52 DK board for the demo.

Building, Flashing and Running
******************************

.. zephyr-app-commands::
   :zephyr-app: samples/boards/nrf52/system_off
   :board: nrf52dk_nrf52832
   :goals: build flash
   :compact:

Running:

1. Open UART terminal.
2. Power Cycle Device.
3. Device will demonstrate two activity levels which can be measured.
4. Device will demonstrate long sleep at minimal non-off power.
5. Device will turn itself off using deep sleep state 1.  Press Button 1
   to wake the device and restart the application as if it had been
   powered back on.

Sample Output
=================
nRF52 core output
-----------------

.. code-block:: console

   *** Booting Zephyr OS build v2.3.0-rc1-204-g5f2eb85f728d  ***

   nrf52dk_nrf52832 system off demo
   Busy-wait 2 s
   Busy-wait 2 s with UART off
   Sleep 2 s
   Sleep 2 s with UART off
   Entering system off; press BUTTON1 to restart