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tests: drivers: adc: Implement ADC latency test
Measure ADC sampling call latency. Signed-off-by: Bartosz Miller <[email protected]>
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‎CODEOWNERS‎

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/tests/drivers/timer/grtc_timer_lfrc/ @nrfconnect/ncs-low-level-test
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/tests/drivers/uart/ @nrfconnect/ncs-low-level-test
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/tests/drivers/watchdog/ @nrfconnect/ncs-low-level-test
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/tests/drivers/adc/ @nrfconnect/ncs-low-level-test
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/tests/lib/at_cmd_parser/ @nrfconnect/ncs-modem
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/tests/lib/at_cmd_custom/ @nrfconnect/ncs-modem
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/tests/lib/at_parser/ @nrfconnect/ncs-modem

‎scripts/ci/tags.yaml‎

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@@ -1748,6 +1748,7 @@ ci_tests_zephyr_drivers_adc:
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files:
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- nrf/tests/zephyr/drivers/adc/
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- zephyr/tests/drivers/adc/
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- nrf/tests/drivers/adc/
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ci_samples_zephyr_drivers_adc:
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files:

‎tests/drivers/adc/adc_latency/CMakeLists.txt‎

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# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
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cmake_minimum_required(VERSION 3.20.0)
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find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
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project(adc_latency)
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FILE(GLOB app_sources src/*.c)
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target_sources(app PRIVATE ${app_sources})

‎tests/drivers/adc/adc_latency/boards/nrf52840dk_nrf52840.overlay‎

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/*
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* Copyright (c) 2025 Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
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*/
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/ {
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aliases {
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tst-timer = &timer0;
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};
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zephyr,user {
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test-gpios = <&gpio1 10 GPIO_ACTIVE_HIGH>;
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io-channels = <&adc 0>;
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io-channel-names = "A2";
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};
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};
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dut_adc: &adc {
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#address-cells = <1>;
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#size-cells = <0>;
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channel@0 {
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reg = <0>;
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zephyr,gain = "ADC_GAIN_1";
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zephyr,reference = "ADC_REF_INTERNAL";
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zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
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zephyr,input-positive = <NRF_SAADC_AIN1>;
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};
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};
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&gpio1 {
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status = "okay";
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};
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&timer0 {
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status = "okay";
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};

‎tests/drivers/adc/adc_latency/boards/nrf5340dk_nrf5340_cpuapp.overlay‎

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/*
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* Copyright (c) 2025 Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
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*/
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/*
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* Required loopbacks:
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* P0.0.5 (AIN1) <-> P0.04
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*/
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/ {
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aliases {
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tst-timer = &timer0;
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};
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zephyr,user {
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test-gpios = <&gpio0 4 GPIO_ACTIVE_HIGH>;
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io-channels = <&adc 0>;
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io-channel-names = "A2";
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};
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};
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dut_adc: &adc {
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#address-cells = <1>;
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#size-cells = <0>;
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channel@0 {
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reg = <0>;
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zephyr,gain = "ADC_GAIN_1";
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zephyr,reference = "ADC_REF_INTERNAL";
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zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
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zephyr,input-positive = <NRF_SAADC_AIN1>;
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};
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};
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&gpio0 {
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status = "okay";
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};
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&timer0 {
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status = "okay";
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};

‎tests/drivers/adc/adc_latency/boards/nrf54h20dk_nrf54h20_cpuapp.overlay‎

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/*
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* Copyright (c) 2025 Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
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*/
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/*
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* Required loopbacks:
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* P1.02 (AIN2) <-> P1.03
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*/
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/ {
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aliases {
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tst-timer = &timer130;
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};
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zephyr,user {
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test-gpios = <&gpio1 3 GPIO_ACTIVE_HIGH>;
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io-channels = <&adc 2>;
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io-channel-names = "A2";
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};
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};
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dut_adc: &adc {
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#address-cells = <1>;
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#size-cells = <0>;
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channel@0 {
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reg = <0>;
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zephyr,gain = "ADC_GAIN_1";
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zephyr,reference = "ADC_REF_INTERNAL";
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zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
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zephyr,input-positive = <NRF_SAADC_AIN2>;
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};
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};
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&gpio1 {
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status = "okay";
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};
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&timer130 {
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status = "okay";
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};

‎tests/drivers/adc/adc_latency/boards/nrf54l15dk_nrf54l15_cpuapp.overlay‎

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/*
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* Copyright (c) 2025 Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
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*/
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/*
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* Required loopbacks:
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* P1.06 (AIN2) <-> VDDIO (Zephyr test loopback set)
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*/
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/ {
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aliases {
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tst-timer = &timer20;
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};
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zephyr,user {
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test-gpios = <&gpio1 11 GPIO_ACTIVE_HIGH>;
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io-channels = <&adc 0>;
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io-channel-names = "A2";
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};
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};
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dut_adc: &adc {
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#address-cells = <1>;
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#size-cells = <0>;
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channel@0 {
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reg = <0>;
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zephyr,gain = "ADC_GAIN_1";
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zephyr,reference = "ADC_REF_INTERNAL";
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zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
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zephyr,input-positive = <NRF_SAADC_AIN1>;
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};
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};
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&gpio1 {
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status = "okay";
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};
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&timer20 {
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status = "okay";
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};

‎tests/drivers/adc/adc_latency/prj.conf‎

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CONFIG_ADC=y
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CONFIG_GPIO=y
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CONFIG_COUNTER=y
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CONFIG_ZTEST=y
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CONFIG_PM_DEVICE_RUNTIME=n

‎tests/drivers/adc/adc_latency/src/main.c‎

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/*
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* Copyright (c) 2025, Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
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*/
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#include <zephyr/kernel.h>
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#include <zephyr/drivers/adc.h>
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#include <zephyr/drivers/gpio.h>
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#include <zephyr/drivers/counter.h>
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#include <zephyr/ztest.h>
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#define ADC_NODE DT_NODELABEL(dut_adc)
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#define DT_SPEC_AND_COMMA(node_id, prop, idx) ADC_DT_SPEC_GET_BY_IDX(node_id, idx),
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#define MEASUREMENT_REPEATS 10
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#define TEST_TIMER_COUNT_TIME_LIMIT_MS 500
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#define ADC_MINIMAL_READING_FOR_HIGH_LEVEL 4000
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#define ADC_BUFFER_MAX_SIZE 500
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#define MAX_TOLERANCE 3.0
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static int16_t adc_sample_buffer[ADC_BUFFER_MAX_SIZE];
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static const struct device *adc = DEVICE_DT_GET(ADC_NODE);
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static const struct gpio_dt_spec test_gpio = GPIO_DT_SPEC_GET(DT_PATH(zephyr_user), test_gpios);
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static struct adc_channel_cfg channel_cfgs[] = {
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DT_FOREACH_CHILD_SEP(ADC_NODE, ADC_CHANNEL_CFG_DT, (,))};
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static const struct adc_dt_spec adc_channels[] = {
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DT_FOREACH_PROP_ELEM(DT_PATH(zephyr_user), io_channels, DT_SPEC_AND_COMMA)};
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const struct device *const tst_timer_dev = DEVICE_DT_GET(DT_ALIAS(tst_timer));
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void configure_test_timer(const struct device *timer_dev, uint32_t count_time_ms)
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{
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struct counter_alarm_cfg counter_cfg;
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counter_cfg.flags = 0;
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counter_cfg.ticks = counter_us_to_ticks(timer_dev, (uint64_t)count_time_ms * 1000);
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counter_cfg.user_data = &counter_cfg;
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}
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void *test_setup(void)
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{
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zassert_true(adc_is_ready_dt(&adc_channels[0]), "ADC channel 0 is not ready\n");
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zassert_true(gpio_is_ready_dt(&test_gpio), "Test GPIO is not ready\n");
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zassert_ok(gpio_pin_configure_dt(&test_gpio, GPIO_OUTPUT),
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"Failed to configure test pin\n");
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gpio_pin_set_dt(&test_gpio, 1);
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return NULL;
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}
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static uint32_t calculate_theoretical_sampling_time_us(uint32_t sampling_interval_us,
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uint16_t extra_samples)
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{
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return sampling_interval_us * (1 + extra_samples);
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}
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/*
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* Note that interval_us >> (tACQ + tconv) must be fulfilled
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* to achieve constant sampling rate
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* tconv is ~2us
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*/
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static void test_adc_latency(uint32_t acquisition_time_us, uint32_t sampling_interval_us,
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uint16_t extra_samples)
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{
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int ret;
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uint32_t tst_timer_value;
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uint64_t timer_value_us[MEASUREMENT_REPEATS];
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uint64_t average_timer_value_us = 0;
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uint64_t theoretical_sampling_time_us;
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uint64_t maximal_allowed_sampling_time_us;
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#if !defined(CONFIG_SOC_NRF52840)
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uint16_t adc_buffer_length = 1 + extra_samples;
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#endif
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const struct adc_sequence_options options = {
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.interval_us = sampling_interval_us,
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.extra_samplings = extra_samples,
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};
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struct adc_sequence sequence = {
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.options = &options,
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.buffer = adc_sample_buffer,
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.buffer_size = sizeof(adc_sample_buffer),
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.channels = 1,
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.resolution = 12,
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};
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channel_cfgs[0].acquisition_time =
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ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, acquisition_time_us);
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TC_PRINT("ADC latency test for %uus acquisition time, %uus sampling interval, %u extra "
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"samples\n",
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acquisition_time_us, sampling_interval_us, extra_samples);
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ret = adc_channel_setup(adc, &channel_cfgs[0]);
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zassert_ok(ret, "ADC channel 0 setup failed\n: %d", ret);
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configure_test_timer(tst_timer_dev, TEST_TIMER_COUNT_TIME_LIMIT_MS);
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theoretical_sampling_time_us =
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calculate_theoretical_sampling_time_us(sampling_interval_us, extra_samples);
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maximal_allowed_sampling_time_us = MAX_TOLERANCE * theoretical_sampling_time_us;
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for (uint32_t repeat_counter = 0; repeat_counter < MEASUREMENT_REPEATS; repeat_counter++) {
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counter_reset(tst_timer_dev);
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counter_start(tst_timer_dev);
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ret = adc_read(adc, &sequence);
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counter_get_value(tst_timer_dev, &tst_timer_value);
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counter_stop(tst_timer_dev);
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zassert_ok(ret, "ADC read failed: %d\n", ret);
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timer_value_us[repeat_counter] =
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counter_ticks_to_us(tst_timer_dev, tst_timer_value);
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average_timer_value_us += timer_value_us[repeat_counter] / MEASUREMENT_REPEATS;
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#if !defined(CONFIG_SOC_NRF52840)
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/*
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* There is no available loopback option
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* to verify the sample data on nrf52840
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*/
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for (int i = 0; i < adc_buffer_length; i++) {
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zassert_true(adc_sample_buffer[i] > ADC_MINIMAL_READING_FOR_HIGH_LEVEL,
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"Sample %u is below the minimal ADC reading for high level\n",
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i);
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}
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#endif
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}
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TC_PRINT("Calculated ADC sampling time for %uus acquisition time, %uus sampling interval, "
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"%u "
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"extra samples [us]: %llu\n",
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acquisition_time_us, sampling_interval_us, extra_samples,
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theoretical_sampling_time_us);
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TC_PRINT("Measured ADC sampling time for %uus acquisition time, %uus sampling interval, %u "
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"extra samples [us]: %llu\n",
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acquisition_time_us, sampling_interval_us, extra_samples, average_timer_value_us);
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TC_PRINT("Measured - calculated ADC sampling time for %uus acquisition time, %uus sampling "
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"interval, %u "
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"extra samples [us]: %lld\n",
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acquisition_time_us, sampling_interval_us, extra_samples,
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average_timer_value_us - theoretical_sampling_time_us);
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zassert_true(average_timer_value_us < maximal_allowed_sampling_time_us,
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"Measured sampling time is over the specified limit\n");
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}
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ZTEST(adc_latency, test_adc_read_call_latency)
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{
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#if defined(CONFIG_SOC_NRF54H20) || defined(CONFIG_SOC_NRF54L15)
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test_adc_latency(5, 40, 9);
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test_adc_latency(5, 40, 99);
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test_adc_latency(5, 40, 499);
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test_adc_latency(20, 100, 9);
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test_adc_latency(20, 100, 99);
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test_adc_latency(20, 100, 499);
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#endif
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test_adc_latency(40, 200, 9);
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test_adc_latency(40, 200, 99);
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test_adc_latency(40, 200, 499);
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}
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ZTEST_SUITE(adc_latency, NULL, test_setup, NULL, NULL, NULL);

‎tests/drivers/adc/adc_latency/testcase.yaml‎

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common:
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tags:
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- drivers
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- ci_tests_zephyr_drivers_adc
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platform_allow:
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- nrf54h20dk/nrf54h20/cpuapp
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- nrf54l15dk/nrf54l15/cpuapp
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- nrf5340dk/nrf5340/cpuapp
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- nrf52840dk/nrf52840
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integration_platforms:
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- nrf54h20dk/nrf54h20/cpuapp
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- nrf54l15dk/nrf54l15/cpuapp
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- nrf5340dk/nrf5340/cpuapp
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- nrf52840dk/nrf52840
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tests:
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drivers.adc.adc_latency: {}

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