99 lines
4.2 KiB
ReStructuredText
99 lines
4.2 KiB
ReStructuredText
.. _nrf53_sync_rtc_sample:
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Synchronized RTC
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################
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Overview
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********
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Sample is showing how RTC clocks used for system clock on application and network
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core are synchronized. The result of synchronization is an offset value on network
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core which can be applied to the system tick for logging timestamping.
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Sample is using IPM driver and IPC HAL to produce events which occur at same time on
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both cores. Application core periodically reads current system tick and stores it in
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the shared memory and triggers IPC task which results in the interrupt on the network
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core. In the context of the IPC interrupt handler, network core is logging timestamp
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from shared memory and local system tick updated by the offset. User can observe
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that before synchronization procedure is completed, timestamps differ significantly
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and once procedure is completed timestamps are synchronized. Network core timestamp
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may be slightly behind (usually 1 tick) due to latency introduced by the
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interrupt handling.
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For simplicity and low latency sample is not using more sophisticated IPM protocols.
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Building the application for nrf5340dk/nrf5340/cpuapp
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*****************************************************
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.. zephyr-app-commands::
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:zephyr-app: samples/boards/nrf/nrf53_sync_rtc
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:board: nrf5340dk/nrf5340/cpuapp
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:goals: flash
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:flash-args: --hex-file build/nrf53_sync_rtc/zephyr/zephyr.hex
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:west-args: --sysbuild
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Open a serial terminals (for example Minicom or PuTTY) and connect the board with the
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following settings:
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- Speed: 115200
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- Data: 8 bits
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- Parity: None
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- Stop bits: 1
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When you reset the development kit, the following messages (one for master and one for remote) will appear on the corresponding serial ports:
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.. code-block:: console
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*** Booting Zephyr OS build v2.7.0-rc1-89-ge755863d66c9 ***
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[00:00:00.306,915] <inf> main: IPC send at 10056 ticks
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[00:00:00.356,903] <inf> main: IPC send at 11695 ticks
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[00:00:00.406,921] <inf> main: IPC send at 13334 ticks
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[00:00:00.456,939] <inf> main: IPC send at 14973 ticks
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[00:00:00.506,958] <inf> main: IPC send at 16612 ticks
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[00:00:00.556,976] <inf> main: IPC send at 18251 ticks
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[00:00:00.606,994] <inf> main: IPC send at 19890 ticks
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[00:00:00.657,012] <inf> main: IPC send at 21529 ticks
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[00:00:00.707,031] <inf> main: IPC send at 23168 ticks
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[00:00:00.757,049] <inf> main: IPC send at 24807 ticks
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.. code-block:: console
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*** Booting Zephyr OS build v2.7.0-rc1-89-ge755863d66c9 ***
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[00:00:00.054,534] <inf> main: Local timestamp: 1787, application core timestamp: 10056
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[00:00:00.104,553] <inf> main: Local timestamp: 3426, application core timestamp: 11695
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[00:00:00.154,571] <inf> main: Local timestamp: 5065, application core timestamp: 13334
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[00:00:00.204,589] <inf> main: Local timestamp: 6704, application core timestamp: 14973
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[00:00:00.254,608] <inf> main: Local timestamp: 8343, application core timestamp: 16612
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[00:00:00.514,892] <inf> sync_rtc: Updated timestamp to synchronized RTC by 8270 ticks (252380us)
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[00:00:00.557,006] <inf> main: Local timestamp: 18252, application core timestamp: 18251
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[00:00:00.607,025] <inf> main: Local timestamp: 19891, application core timestamp: 19890
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[00:00:00.657,043] <inf> main: Local timestamp: 21530, application core timestamp: 21529
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[00:00:00.707,061] <inf> main: Local timestamp: 23169, application core timestamp: 23168
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[00:00:00.757,080] <inf> main: Local timestamp: 24807, application core timestamp: 24807
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Observe that initially logging timestamps for the corresponding events on both cores
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do not match. Same with local and remote timestamps reported on network core. After
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RTC synchronization is completed they start to match.
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.. _nrf53_sync_rtc_sample_build_bsim:
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Building the application for the simulated nrf5340bsim
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******************************************************
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.. zephyr-app-commands::
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:zephyr-app: samples/boards/nrf/nrf53_sync_rtc
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:host-os: unix
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:board: nrf5340bsim/nrf5340/cpuapp
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:goals: build
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:west-args: --sysbuild
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Then you can execute your application using:
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.. code-block:: console
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$ ./build/zephyr/zephyr.exe -nosim
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# Press Ctrl+C to exit
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You can expect a similar output as in the real HW in the invoking console.
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