samples: boards: nrf: add clock_skew
Provide a demonstration of using the timeutil skew infrastructure to measure the relative error of the two clock sources on Nordic boards. Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
This commit is contained in:
Peter Bigot
Anas Nashif
parent
7b3dc4856a
commit
08f4ce4efb
8
samples/boards/nrf/clock_skew/CMakeLists.txt
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8
samples/boards/nrf/clock_skew/CMakeLists.txt
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# SPDX-License-Identifier: Apache-2.0
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cmake_minimum_required(VERSION 3.13.1)
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find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
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project(nrf_clock_skew)
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FILE(GLOB app_sources src/*.c)
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target_sources(app PRIVATE ${app_sources})
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10
samples/boards/nrf/clock_skew/Kconfig
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10
samples/boards/nrf/clock_skew/Kconfig
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# Copyright (c) 2020, Nordic Semiconductor ASA
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# SPDX-License-Identifier: Apache-2.0
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config APP_ENABLE_HFXO
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bool "Use HFXO as HFCLK source"
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help
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Turn on the high-frequency clock, which means switching to the
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crystal as a source rather than the internal oscillator.
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source "Kconfig.zephyr"
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116
samples/boards/nrf/clock_skew/README.rst
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116
samples/boards/nrf/clock_skew/README.rst
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.. _nrf-clock-skew-sample:
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nRF5x Clock Skew Demo
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#####################
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Overview
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********
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This sample uses the API for correlating time sources to measure the
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skew between HFCLK (used for the CPU) and LFCLK (used for system time).
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The ``CONFIG_APP_ENABLE_HFXO`` Kconfig option can be select to configure
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the high frequency clock to use a crystal oscillator rather than the
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default RC oscillator. (Capabilities like Bluetooth that require an
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accurate high-frequency clock generally enable this source
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automatically.) The relative error is significantly lower when HFXO is
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enabled.
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Requirements
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************
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This application uses any 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/nrf/clock_skew
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:board: nrf52dk_nrf52840
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:goals: build flash
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:compact:
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Running:
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Sample Output
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=============
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.. code-block:: console
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*** Booting Zephyr OS build zephyr-v2.4.0-693-g4a3275faf567 ***
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Power-up clocks: LFCLK[ON]: Running LFXO ; HFCLK[OFF]: Running HFINT
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Start TIMER_0: 0
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Timer-running clocks: LFCLK[ON]: Running LFXO ; HFCLK[OFF]: Running HFINT
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Checking TIMER_0 at 16000000 Hz against ticks at 32768 Hz
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Timer wraps every 268 s
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Ty Latest Base Span Err
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HF 00:00:00.015667
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LF 00:00:00.404296
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Started sync: 0
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Ty Latest Base Span Err
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HF 00:00:10.001151 00:00:00.015667 00:00:09.985483
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LF 00:00:10.413818 00:00:00.404296 00:00:10.009521 00:00:00.024038
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Skew 0.997599 ; err 2401411 ppb
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Ty Latest Base Span Err
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HF 00:00:19.997456 00:00:00.015667 00:00:19.981788
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LF 00:00:20.434265 00:00:00.404296 00:00:20.029968 00:00:00.048180
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Skew 0.997595 ; err 2405464 ppb
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Ty Latest Base Span Err
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HF 00:00:29.993845 00:00:00.015667 00:00:29.978178
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LF 00:00:30.454650 00:00:00.404296 00:00:30.050354 00:00:00.072176
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Skew 0.997598 ; err 2401828 ppb
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Ty Latest Base Span Err
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HF 00:00:39.986181 00:00:00.015667 00:00:39.970514
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LF 00:00:40.475036 00:00:00.404296 00:00:40.070739 00:00:00.100225
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Skew 0.997499 ; err 2501189 ppb
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Ty Latest Base Span Err
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HF 00:00:49.981516 00:00:00.015667 00:00:49.965848
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LF 00:00:50.495422 00:00:00.404296 00:00:50.091125 00:00:00.125277
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Skew 0.997499 ; err 2501010 ppb
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Ty Latest Base Span Err
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HF 00:00:59.976042 00:00:00.015667 00:00:59.960375
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LF 00:01:00.515808 00:00:00.404296 00:01:00.111511 00:00:00.151136
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Skew 0.997486 ; err 2514243 ppb
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...
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Ty Latest Base Span Err
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HF 00:01:59.935661 00:00:00.015667 00:01:59.919994
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LF 00:02:00.638153 00:00:00.404296 00:02:00.233856 00:00:00.313862
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Skew 0.997390 ; err 2610445 ppb
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...
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Ty Latest Base Span Err
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HF 00:04:59.769166 00:00:00.015667 00:04:59.753498
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LF 00:05:01.005279 00:00:00.404296 00:05:00.600982 00:00:00.847484
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Skew 0.997181 ; err 2819240 ppb
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...
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Ty Latest Base Span Err
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HF 00:09:59.513787 00:00:00.015667 00:09:59.498119
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LF 00:10:01.617156 00:00:00.404296 00:10:01.212860 00:00:01.714741
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Skew 0.997148 ; err 2852201 ppb
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...
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Ty Latest Base Span Err
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HF 00:30:08.384536 00:00:00.015667 00:30:08.368868
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LF 00:30:14.084594 00:00:00.404296 00:30:13.680297 00:00:05.311429
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Skew 0.997072 ; err 2928495 ppb
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...
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Ty Latest Base Span Err
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HF 00:59:57.353602 00:00:00.015667 00:59:57.337934
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LF 01:00:07.734375 00:00:00.404296 01:00:07.330078 00:00:09.992144
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Skew 0.997230 ; err 2770006 ppb
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...
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Ty Latest Base Span Err
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HF 02:59:33.181323 00:00:00.015667 02:59:33.165656
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LF 03:00:03.434265 00:00:00.404296 03:00:03.029968 00:00:29.864312
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Skew 0.997236 ; err 2764463 ppb
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...
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Ty Latest Base Span Err
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HF 05:59:55.031709 00:00:00.015667 05:59:55.016042
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LF 06:00:57.120941 00:00:00.404296 06:00:56.716644 00:01:01.700602
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Skew 0.997151 ; err 2849042 ppb
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5
samples/boards/nrf/clock_skew/prj.conf
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5
samples/boards/nrf/clock_skew/prj.conf
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#CONFIG_CLOCK_CONTROL=y
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CONFIG_COUNTER=y
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CONFIG_COUNTER_TIMER0=y
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CONFIG_NEWLIB_LIBC=y
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CONFIG_NEWLIB_LIBC_FLOAT_PRINTF=y
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7
samples/boards/nrf/clock_skew/sample.yaml
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7
samples/boards/nrf/clock_skew/sample.yaml
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sample:
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name: Clock Skew Sample for nRF
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tests:
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sample.boards.nrf.clock_skew:
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build_only: true
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platform_allow: nrf52840dk_nrf52840 nrf52dk_nrf52832 nrf51dk_nrf51422
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tags: power
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234
samples/boards/nrf/clock_skew/src/main.c
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234
samples/boards/nrf/clock_skew/src/main.c
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/*
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* Copyright (c) 2020 Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <stdio.h>
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#include <zephyr.h>
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#include <sys/timeutil.h>
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#include <drivers/clock_control.h>
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#include <drivers/clock_control/nrf_clock_control.h>
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#include <drivers/counter.h>
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#include <nrfx_clock.h>
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#define TIMER_NODE DT_NODELABEL(timer0)
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#define CLOCK_NODE DT_INST(0, nordic_nrf_clock)
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#define UPDATE_INTERVAL_S 10
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static const struct device *clock0;
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static const struct device *timer0;
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static struct timeutil_sync_config sync_config;
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static uint64_t counter_ref;
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static struct timeutil_sync_state sync_state;
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static struct k_delayed_work sync_work;
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/* Convert local time in ticks to microseconds. */
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uint64_t local_to_us(uint64_t local)
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{
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return z_tmcvt(local, sync_config.local_Hz, USEC_PER_SEC, false,
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false, false, false);
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}
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/* Convert HFCLK reference to microseconds. */
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uint64_t ref_to_us(uint64_t ref)
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{
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return z_tmcvt(ref, sync_config.ref_Hz, USEC_PER_SEC, false,
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false, false, false);
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}
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/* Format a microsecond timestamp to text as D d HH:MM:SS.SSSSSS. */
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static const char *us_to_text_r(uint64_t rem, char *buf, size_t len)
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{
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char *bp = buf;
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char *bpe = bp + len;
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uint32_t us;
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uint32_t s;
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uint32_t min;
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uint32_t hr;
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uint32_t d;
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us = rem % USEC_PER_SEC;
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rem /= USEC_PER_SEC;
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s = rem % 60;
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rem /= 60;
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min = rem % 60;
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rem /= 60;
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hr = rem % 24;
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rem /= 24;
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d = rem;
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if (d > 0) {
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bp += snprintf(bp, bpe - bp, "%u d ", d);
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}
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bp += snprintf(bp, bpe - bp, "%02u:%02u:%02u.%06u",
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hr, min, s, us);
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return buf;
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}
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static const char *us_to_text(uint64_t rem)
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{
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static char ts_buf[32];
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return us_to_text_r(rem, ts_buf, sizeof(ts_buf));
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}
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/* Show status of various clocks */
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static void show_clocks(const char *tag)
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{
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static const char *const lfsrc_s[] = {
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#if defined(CLOCK_LFCLKSRC_SRC_LFULP)
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[NRF_CLOCK_LFCLK_LFULP] = "LFULP",
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#endif
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[NRF_CLOCK_LFCLK_RC] = "LFRC",
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[NRF_CLOCK_LFCLK_Xtal] = "LFXO",
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[NRF_CLOCK_LFCLK_Synth] = "LFSYNT",
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};
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static const char *const hfsrc_s[] = {
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[NRF_CLOCK_HFCLK_LOW_ACCURACY] = "HFINT",
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[NRF_CLOCK_HFCLK_HIGH_ACCURACY] = "HFXO",
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};
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static const char *const clkstat_s[] = {
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[CLOCK_CONTROL_STATUS_STARTING] = "STARTING",
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[CLOCK_CONTROL_STATUS_OFF] = "OFF",
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[CLOCK_CONTROL_STATUS_ON] = "ON",
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[CLOCK_CONTROL_STATUS_UNKNOWN] = "UNKNOWN",
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};
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union {
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unsigned int raw;
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nrf_clock_lfclk_t lf;
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nrf_clock_hfclk_t hf;
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} src;
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enum clock_control_status clkstat;
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bool running;
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clkstat = clock_control_get_status(clock0, CLOCK_CONTROL_NRF_SUBSYS_LF);
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running = nrf_clock_is_running(NRF_CLOCK, NRF_CLOCK_DOMAIN_LFCLK,
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&src.lf);
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printk("%s: LFCLK[%s]: %s %s ; ", tag, clkstat_s[clkstat],
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running ? "Running" : "Off", lfsrc_s[src.lf]);
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clkstat = clock_control_get_status(clock0, CLOCK_CONTROL_NRF_SUBSYS_HF);
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running = nrf_clock_is_running(NRF_CLOCK, NRF_CLOCK_DOMAIN_HFCLK,
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&src.hf);
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printk("HFCLK[%s]: %s %s\n", clkstat_s[clkstat],
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running ? "Running" : "Off", hfsrc_s[src.hf]);
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}
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static void sync_work_handler(struct k_work *work)
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{
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uint32_t ctr;
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int rc = counter_get_value(timer0, &ctr);
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const struct timeutil_sync_instant *base = &sync_state.base;
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const struct timeutil_sync_instant *latest = &sync_state.latest;
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if (rc == 0) {
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struct timeutil_sync_instant inst;
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uint64_t ref_span_us;
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counter_ref += ctr - (uint32_t)counter_ref;
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inst.ref = counter_ref;
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inst.local = k_uptime_ticks();
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rc = timeutil_sync_state_update(&sync_state, &inst);
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printf("\nTy Latest Base Span Err\n");
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printf("HF %s", us_to_text(ref_to_us(inst.ref)));
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if (rc > 0) {
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printf(" %s", us_to_text(ref_to_us(base->ref)));
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ref_span_us = ref_to_us(latest->ref - base->ref);
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printf(" %s", us_to_text(ref_span_us));
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}
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printf("\nLF %s", us_to_text(local_to_us(inst.local)));
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if (rc > 0) {
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uint64_t err_us;
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uint64_t local_span_us;
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char err_sign = ' ';
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printf(" %s", us_to_text(local_to_us(base->local)));
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local_span_us = local_to_us(latest->local - base->local);
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printf(" %s", us_to_text(local_span_us));
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if (ref_span_us >= local_span_us) {
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err_us = ref_span_us - local_span_us;
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err_sign = '-';
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} else {
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err_us = local_span_us - ref_span_us;
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}
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printf(" %c%s", err_sign, us_to_text(err_us));
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}
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printf("\n");
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if (rc > 0) {
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float skew = timeutil_sync_estimate_skew(&sync_state);
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printf("Skew %f ; err %d ppb\n", skew,
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timeutil_sync_skew_to_ppb(skew));
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} else if (rc < 0) {
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printf("Sync update error: %d\n", rc);
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}
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}
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k_delayed_work_submit(&sync_work, K_SECONDS(UPDATE_INTERVAL_S));
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}
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void main(void)
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{
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const char *clock_label = DT_LABEL(CLOCK_NODE);
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const char *timer0_label = DT_LABEL(TIMER_NODE);
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uint32_t top;
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int rc;
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/* Grab the clock driver */
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clock0 = device_get_binding(clock_label);
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if (clock0 == NULL) {
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printk("Failed to fetch clock %s\n", clock_label);
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}
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show_clocks("Power-up clocks");
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if (IS_ENABLED(CONFIG_APP_ENABLE_HFXO)) {
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rc = clock_control_on(clock0, CLOCK_CONTROL_NRF_SUBSYS_HF);
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printk("Enable HFXO got %d\n", rc);
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}
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/* Grab the timer. */
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timer0 = device_get_binding(timer0_label);
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if (timer0 == NULL) {
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printk("Failed to fetch timer0 %s\n", timer0_label);
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return;
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}
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/* Apparently there's no API to configure a frequency at
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* runtime, so live with whatever we get.
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*/
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sync_config.ref_Hz = counter_get_frequency(timer0);
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if (sync_config.ref_Hz == 0) {
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printk("Timer %s has no fixed frequency\n",
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timer0_label);
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return;
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}
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top = counter_get_top_value(timer0);
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if (top != UINT32_MAX) {
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printk("Timer %s wraps at %u (0x%08x) not at 32 bits\n",
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timer0_label, top, top);
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return;
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}
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rc = counter_start(timer0);
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printk("Start %s: %d\n", timer0_label, rc);
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show_clocks("Timer-running clocks");
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sync_config.local_Hz = CONFIG_SYS_CLOCK_TICKS_PER_SEC;
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sync_state.cfg = &sync_config;
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printf("Checking %s at %u Hz against ticks at %u Hz\n",
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timer0_label, sync_config.ref_Hz, sync_config.local_Hz);
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printf("Timer wraps every %u s\n",
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(uint32_t)(BIT64(32) / sync_config.ref_Hz));
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k_delayed_work_init(&sync_work, sync_work_handler);
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rc = k_delayed_work_submit(&sync_work, K_NO_WAIT);
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printk("Started sync: %d\n", rc);
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}
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